CHILTON Automotive Community

Top 5 Brake Complaints and How to Resolve Them

Jim Marotta — Wed, 25 May 2011 16:14:00 GMT

By Jim Marotta

I think we can all agree that the braking system is the most important safety device on any vehicle. Since people place such a high value on their car's ability to slow and stop, it is smart to pay attention when they complain about the brakes.

Let's review the five most common brake complaints and how to resolve them.

1. Noise

Brake noise, or squealing, is the most obvious problem to drivers. Unwanted movement of brake components causes the noise. What's the solution? Keep brake components in place per factory specifications and properly prepare surfaces during service.

According to Chuck Kennedy, Bendix Technical Training Manager, "Today's brake systems are very sensitive to rust and corrosion and should receive a thorough cleaning in preparation for fresh lubricant, hardware, and friction material. Residual rust or corrosion left in critical areas can begin to cause brake issues almost immediately."

In addition to the normal inspections for binding, corrosion, lack of lubrication, and worn or damaged components, clean the caliper moving parts and retaining hardware. Clean pin bores with a round wire brush and cleaner to remove old lubricant and corrosion.

Caliper pins can cause binding. Clean the caliper moving parts and retention hardware of dirt, corrosion and rust. Clean pin bores with a round wire brush and cleaner to remove old lubricant and corrosion.

Pad abutments need to be clean and smooth, whether they are part of the caliper bracket or steering knuckle. If there are notches or grooves caused by pad movement, replace these parts. Damage like this can cause excessive pad movement that leads to noise and vibration.

It may be counterintuitive to clean a new or freshly machined rotor with soap, warm water, and a stiff brush, but this simple step removes fine, metal particles from the surface and pores, which if left there, can embed in the friction material, causing brake noise.

Clean, inspect and adjust rear calipers or drum brake systems before the vehicle gets back on the road. If there are grooves on the backing plate shoe support pads, replace the backing plates. This prevents shoe chatter and improper brake shoe return, which leads to grabbing and premature shoe failure.

2. Pulsation

Pulsation is another issue that is obvious to the driver. Check for rotor lateral runout and thickness variations that point to pulsation issues. Do not forget to check the hubs. Hubs can be the culprit while the rotor shows the symptoms.

Checking for rotor thickness variations will help diagnose pulsation issues.

Use a polishing pad to clean as much rust as possible from the hub face and next to the studs. Leaving corrosion in these areas is one of the top causes of pulsation.

An often overlooked area is the wheel hub mounting pad. If there is rust or debris in this area, it can lead to rotor distortion and pulsation just as easily as if debris were left on the hub.

Another common cause of pulsation is uneven tightness of wheel lugs. Lighter components on today's vehicles can be easily distorted. Eliminate this issue by lightly seating and then torquing wheels to specification in two stages. On wheels with lug-centric hubs, rotate the wheel as the lugs are seated to help keep the wheel centered on the hub.

What do you do if all else fails and there is still pulsation? Check the tire and wheel assemblies for speed-dependent, loaded, radial force variations. A tire or wheel rim out-of-round or imbalanced can cause a pulsation similar to the pulsation caused by rotor problems.

3. Dust

When applying braking force, small amounts of material gradually abrade from the brake pads. This material, known as "brake dust," usually deposits on the braking system and the surrounding wheel.

The proper friction material choice can affect dusting. Different brake pad formulations create different amounts of dust, and some formulations, particularly metallic brake pads, create more dust than others. Ceramic brake pads contain significantly fewer metal particles, and therefore produce less abrasion of surrounding metal parts.

Rob Backode, Director of Product Management for Bosch Automotive Aftermarket Brake Components reports that "The number of complaints about brake dust is far, far fewer with more service shops installing ceramic-type brake pads."

Brake dust can be more than just a visual nuisance; it can badly damage the finish of most wheels if not washed off. Removing brake dust can eliminate other problems and avoid customer complaints.

Some technicians tape off the brake shoes to prevent contamination during service.

4. Excessive Wear

Common complaints due to excessive wear are usually due to lack of maintenance, hard driving style, or vehicle usage characteristics. Brakes on one vehicle may last substantially longer if the owner drives it easy or takes more highway trips. If the owner overloads the vehicle, makes short, stop-and-go trips, or leaves one foot on the brake pedal while driving, the pads will have more wear and failures from the abuse.

Common complaints due to excessive wear are usually due to lack of maintenance, driving style, or the way the vehicle is being used.

Residual pressure trapped in the hydraulic system can lead to excessive wear and premature failure of friction materials. Quickly determine whether it is a mechanical or hydraulic issue by cracking a bleeder screw on a caliper that shows drag. If fluid comes out and the caliper releases, then a component is restricting fluid return to the master cylinder reservoir. If no fluid escapes and the drag remains, then it is a mechanical issue within the caliper or slides.

Residual pressure trapped in the hydraulic system can cause excessive wear and premature failure of friction materials and surfaces.

5. Stopping Performance

Stopping performance is crucial for today's high performance vehicles and driving conditions. Poor performance can be related to a previous brake job that was done improperly, failing components, vehicle overloading, or installing the wrong type of friction material. Proper inspection, preparation, and break-in are the best ways to overcome these issues.

Pad burnishing or break-in is recommended by many original vehicle manufacturers, but not all. When recommended, a proper burnishing or break-in of the friction material and rotor surface will enhance brake performance, reduce noise, and give the best life possible for the pad materials installed. Burnishing works by mating the two surfaces together to allow proper heat dissipation. It also transfers a film from the friction material to the rotor surface that will enhance its performance.

Old Concerns, New Problems

While there are issues we no longer have to deal with on today's vehicles thanks to technological advancements, some changes create new challenges. Improvements in materials such as rubber and composites lengthen the service life of brake components. Modern, synthetic lubricants give more protection, last longer, withstand higher temperatures, and are compatible with rubber components.

Lubricants have improved in recent years, give more protection, last longer, sustain higher temperatures, and the synthetic compounds are compatible for use with rubber components.

The smaller components and lighter weight of the brake components and the vehicle itself drive many of the changes. Less mass increases the chance for noises to occur. Vehicle manufacturers use more anti-rattle clips and hardware to help control brake noise. Brake systems run at much higher temperatures, requiring improved lubricants.

Pulsation issues increased when rotors went from integral hub/rotor assemblies to over-the-stud mounted assemblies. Corrosion between the assembled hub, rotor, and wheel gives rise to runout and pulsation issues.

As vehicles continually change, we may leave some problems in the past, but we look for new tools, procedures, and information to solve issues on modern cars and trucks. Servicing modern vehicles is more exacting and detail-oriented. Leaving out important steps increases the chance for customer complaints and comebacks. Thorough inspection, diagnosis, and repair procedures are the best way to keep customers satisfied and their vehicles performing up to their expectations.

Resolve your customer's major and minor brake complaints with a subscription to ChiltonPRO, the smart technician's guide to new technologies and old. Just click here to see ChiltonPRO and learn what's coming next to your service bay.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Eight A/C Service Mistakes That Can Make You Sweat

Jim Marotta — Tue, 29 Mar 2011 20:24:00 GMT

By Jim Marotta

What was once a basic system to heat and cool the interior of a vehicle has become a multi-zone, automatic temperature control system with cabin air filtration. No longer are a few tools and some basic knowledge adequate to diagnose and service modern climate control systems. Without proper tools and up-to-date information, mistakes are inevitable.

Let's take a look at the eight most common mistakes techs make when servicing climate control systems.

1. Not Identifying the System Refrigerant

Do you know what type of refrigerant is in your A/C system? This is important information because if you mix refrigerants, the system will not function properly and the wrong refrigerant may damage components. More importantly, if there are non-approved hydrocarbon blend refrigerants in your A/C system, it could be explosive!

The only way to know what is in an A/C system or container is to use a refrigerant identifier. Owning one also helps you to avoid damage to your air conditioning service equipment from contaminated refrigerant and prevents contamination of your refrigerant supply, warranty loss on recovery equipment, and even risk of injury.

The identifier found contaminants in the system and registered "FAIL," telling the tech to evacuate and replace the refrigerant.

2. Not Using the Specified Lubricant

The manufacturer of the vehicle or A/C compressor designs each air conditioning system for a specific viscosity and type of lubricant. While some aftermarket lubricant suppliers claim their oils are universal for every application, these lubricants will usually work best for one situation, but not nearly as well for others.

If you are servicing an older vehicle and CFC-12 is the refrigerant, manufacturers specify the use of mineral oil as the lubricant. A vehicle retrofitted for use with HFC-134a uses polyalkaline glycol (PAG) oil. For vehicles originally equipped with HFC-134a use the OEM-specified viscosity PAG lubricant.

In general, manufacturers offer three viscosities, or thicknesses, of PAG oil. The smaller number indicates less viscous oil. Many Nippon-Denso style compressors use the 46 centistoke lubricant; this includes many of the Ford and Chrysler compressors. Several import and aftermarket compressors use the 100 centistoke lubricant. General Motors uses the 150 centistoke lubricant primarily on the Delphi-Harrison compressors.

The manufacturer of the vehicle or compressor determines the viscosity and lubricant type. While lubricant suppliers claim their oils are universal, each lubricant will usually work best for one situation.

3. Improperly Recharging Systems

Early A/C systems required large quantities of refrigerant; 3 lbs. or more was not uncommon. Charge tolerances for these systems were also reasonable. A simple digital scale and charging station could easily handle the service.

Today most passenger cars and light duty trucks carry less than 20 ounces of refrigerant, or just over 1 lb. One of the smallest capacity systems on the market is the Toyota Yaris, which runs on approximately 11 ounces. With the accuracy of some older scales at plus or minus 0.2 lbs., or more than 3 ounces, the possibility of over- or undercharging a system becomes a definite possibility.

Just 2 ounces of over- or undercharging reduces performance, and 2 ounces of undercharging also affects compressor lubrication. For greater accuracy, use a charging station certified to SAE International standard J2788.

Just 2 ounces of over- or undercharging reduces system performance, and 2 ounces of undercharging also affects compressor lubrication. For greater accuracy use a charging station certified to SAE standard J2788, such as the one shown.

4. Not Using Approved Refrigerants

At present, there are only two OEM recommended refrigerants; CFC-12 and HFC-134a, with a third to come shortly. OEMs specify CFC-12 for use in vehicles manufactured prior to 1992, when they changed to HFC-134a. Currently HFC-134a is the only refrigerant automakers specify for use as a retrofit refrigerant for CFC-12 vehicles. Automakers and compressor manufacturers design current HFC-134a mobile A/C systems only for HFC-134a refrigerant and the specific lubricant, polyalkaline glycol (PAG).

Although companies market a number of other refrigerants that contain hydrocarbon blends, the EPA does not accept them. Beware of inexpensive refrigerants being advertised as "Accepted." Use trustworthy brands.

5. Using Components with Incorrect Performance Specifications

In many cases when servicing an air conditioning system, replacement parts are expensive and there's an incentive to save money by purchasing inferior parts. In a typical expansion valve type air conditioning system, refrigerant absorbs heat in the evaporator. Afterwards, the refrigerant gives up the heat in the condenser and the process continues in a cycle.

If either of these heat exchangers, or the radiator-the third heat exchanger- does not match OEM specifications for performance, the system will not operate properly. A part may look the same as the original and bolt in place correctly, but that does not mean it meets OEM performance. Check the specs and avoid the hassle.

6. Not Performing a Thorough System Evacuation

Depending on the ambient temperature, many older recovery/recycling machines in operation today may only recover 50% of the refrigerant from a system. Even the best machines that far exceed the old SAE J2210 standard requirements may leave up to 30% of the refrigerant behind.

Here is an example: In a system with a 16-oz capacity and 12 ounces remaining in the system, you might unknowingly recover only half the charge. That leaves six ounces of refrigerant remaining in the system. When you recharge the system with 15 oz. of fresh refrigerant, the system will have 21 ounces and be overcharged by 38%.

Fortunately, if you purchased a recovery/recycle machine that conforms to the SAE J2788 standard, you will recover 95% of the refrigerant. Testing also indicates that these new machines' more powerful compressors draw down to far deeper vacuums.

If you are using any older recovery/recycling machine to evacuate the A/C system, it may only recover 50% of the refrigerant, while newer machines recover 95%.

7. Improperly Flushing the System

When any mechanical component of the system has a catastrophic failure, debris may spread throughout the refrigerant loop. Flushing to remove debris that could cause failure of the replacement compressor and to remove debris that could impede refrigerant flow through the condenser is only natural. But flush with the wrong product or use the wrong procedure and you could do more harm than good.

Once again, this is the time to follow the manufacturer's recommendations, which can vary considerably. For example, General Motors recommends flushing with liquid refrigerant, while Ford recommends a liquid flushing solvent. Both manufacturers also recommend using a closed loop flushing machine.

While the flushing agent may be different, flushing with a closed loop flushing machine is the best method for removing all debris from the system.

8. Not Checking for Leaks

Depending on when you make a repair, the owner might not use the system again for months. If a small leak exists, the system might operate well right after repairs, but not months later. Refrigerant escapes easily from small leaks in a damaged system, and it's not always easy to notice the leak. Electronic leak detectors can find leaks effectively and are one of the most efficient ways to check your repairs or deal with a problem leak.

Since the EPA tightly regulates gas release and can fine violators heavily, performing a proper leak inspection after making repairs is advisable.

Refrigerant escapes easily from small leaks in a damaged system, and the evidence of the leak isn't always easy to notice. Electronic leak detectors can find leaks efficiently.

Make sure you have the information you need to avoid A/C service mistakes. A subscription to ChiltonPRO, with comprehensive service information and capacity specifications, will give you all the information you need to keep your A/C system in top shape for the warm weather.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Oil Change: What is the best maintenance interval?

Jim Marotta — Wed, 16 Feb 2011 23:05:00 GMT

By Jim Marotta

The 3,000 mile oil and filter change is as much a part of the American car culture as hot rods, car hops and whitewall tires. Whether we perform it ourselves in the driveway or watch while the family “mechanic” puts the car up on the lift and drains the oil, we think of the 3,000 mile number as the standard interval for oil change service. But, look at a current maintenance interval chart; manufacturers are gradually extending service intervals.

What is the best interval for an oil change? Manufacturers are extending service intervals. Photo by Jim Marotta.

The move toward extended service intervals coincides with new oil technologies that allow manufacturers and refiners to create more stable oils that will endure longer service, and a decrease in the frequency of other services such as tune-ups.

Conventional vs. Synthetic

Traditionally, manufacturers made conventional engine oils from a mineral base oil stock derived from crude oil. Synthetic base oil stocks are produced by either highly processing and refining mineral based oil stock, or by chemically engineering synthetic base oil stock. Current additive packages blended into conventional oils allow them to function longer than oils of the past, but it is primarily the synthetic base stocks that allow greatly extended intervals.

Synthetic oil offers many advantages in durability versus conventional petroleum oil and it is all based on the synthetic oil’s superior resistance to heat and oxidation while requiring little or no viscosity index improvements which are the most vulnerable to degradation as oil ages. Synthetic oil is more accurately controlled at the molecular level and therefore can be engineered to resist the forces in an engine that work against oil durability.

How Long Does Engine Oil Last?

Clearly there is a degree of ambiguity about how long motor oil actually lasts. Traditionally vehicle owners have felt more comfortable with convenient mileage or time-based schedules while others prefer seasonal changes, but the question still remains – how long does engine oil last?

Many factors contribute to the degradation of motor oil. Extreme heat breaks down oil molecules which evaporate and leave deposits on internal engine surfaces, inhibiting the transfer of engine heat to the oil. Oxidation, which is accelerated by heat, further inhibits heat transfer. Environmental contaminants such as dust and dirt enter the engine through improperly maintained filters, and normal engine wear produces metallic particles that travel through the engine increasing wear. Byproducts of normal combustion – soot, dirt, and sludge – contaminate the oil and change viscosity. Finally, internal pressure breaks down the oil film between moving parts which agitate the oil, trapping and suspending air and promoting oxidation.

Lubricant manufacturers continually research and experiment with various chemical additives that in some cases comprise 20 percent of a typical multi-grade oil. In addition to viscosity index improvements, which are the primary additives that allow for multi-grade oils, manufacturers use rust and corrosion inhibitors to neutralize acidic oxidation of the oil. Manufacturers use detergents and dispersants to minimize sludge buildup, along with anti-foaming agents and pressure additives to prevent oil barrier breakdown between internal engine parts. This is known as the shear factor. Manufacturers use additives to aid the base oil in the protection of engine components, but each has limitations and can be affected by the same factors that degrade base oils.

Chemical additives can comprise 20 percent of a typical multi-grade oil. Photo by Jim Marotta.

How Do I Know When My Oil Needs To Be Changed?

One solution presented by the automobile manufacturers is an oil life monitor. Several types of systems exist that use technology to directly “read” the oil. The most popular of these systems rely on capacitance. Using two conducting plates separated by the oil, which acts as an insulating fluid, the system calculates a base capacitance number. As the oil degrades, the system measures the change in capacitance.

Other systems use algorithms to predict oil change intervals.The algorithms are based primarily on factors such as driving habits, driving speed, and failure to replenish low oil levels. Research determined that these factors contribute to oil breakdown. The algorithm method systems also monitor time between oil changes, vehicle speed, coolant temperature, load signal, engine rpm, engine oil temperature and engine oil level to determine the remaining time and mileage before the next oil change. General Motors' Oil Life System and Chrysler Corporation’s Flexible Service System (FSS) are good examples of this type of system.

General Motors’ Oil Life System is based on algorithms that attempt to predict oil change intervals. Photo courtesy of GM.

Goodbye Dipstick?

A new multifunctional system determines oil level and oil condition. The system determines viscosity using a piezoelectric listening device. When this sensitive surface comes into contact with the oil, the oscillation frequency and damping change according to the oil’s mechanical properties, allowing viscosity to be measured. The addition of oil level sensing capability may allow vehicle manufacturers to remove the oil dipstick from the engine.

So, the best answer to our question of how long engine oil lasts is, “it all depends.” Follow the manufacturer’s fluid specifications and maintenance intervals when servicing your vehicle. Get them at www.ChiltonDIY.com or www.ChiltonPRO.com, where a valuable subscription to comprehensive service procedures, specifications, and wiring diagrams, gives you all the information to do the job right.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Cylinder Head Gaskets - Sealing Under Pressure

Jim Marotta — Tue, 21 Dec 2010 18:14:00 GMT

By Jim Marotta

A head gasket's job is to seal combustion gases within the combustion chamber and to prevent coolant and oil from escaping the engine at the head-to-block joint. These requirements have not changed over the years, but the engine operating environment has. Increased cylinder pressures and temperatures, the use of dissimilar block and head materials, and the trend toward lighter-weight engine castings and reduced head clamp loads result in operating conditions that cause much higher levels of horizontal and vertical motion between the head and block.

After only a few thousand miles of operation the finishes and flatness of engine surfaces are no longer virgin castings: the engine has the engine has heated and cooled repeatedly, making the job of sealing much more difficult.

Another challenge facing modern-day head gaskets is zero tolerance for even minor combustion or fluid leaks, primarily due to emissions requirements. Today's head gaskets have to provide a perfect, lock-tight seal in spite of ever increasing pressures, temperatures and other dynamic forces.

Evolving Head Gasket Technology

The original head gasket technology is known as a sandwich-style gasket. Sandwich gaskets combine metal-faced materials with a filler material in between. Since engines of the day were low horsepower and low compression, these gaskets sealed engines adequately into the late 1950s.

As engines grew bigger and more powerful in the early 1960s, some manufacturers started using embossed steel shim-style gaskets. While the steel shim gaskets were even lower tech than their predecessors, they led the way to today's multi-layer steel head gaskets.

The later '60s saw the rise of a new type of composite gasket featuring a perforated steel core with a composite face material applied to each side. These were the first head gaskets that didn't need a secondary (spray-on or brush-on) coating to create a micro-seal between cylinder head and block, or re-torquing.

As engine technology progressed, conventional composite-style head gaskets couldn't withstand the increased casting motion in the new smaller, lighter, and more powerful engines. Lateral motion between the aluminum head and iron block was destroying the facing material through a shearing action, and the vertical motion - in which the head was actually moving away from the block - was over-compressing the gasket.

During the late 1970s and early 80s gaskets contained expanded graphite facing material mechanically clinched to a steel core, offering excellent conformability to surface finish variations. The natural lubricity of expanded graphite accommodated some casting motion, which occurred frequently in the early days of bi-metallic engines.

In the early 1990s, manufacturers introduced Multi-Layer Steel (MLS) head gaskets. Engines using these gaskets featured higher combustion temperatures and pressures, lighter-weight castings, and reduced head-to-block torque loads to prevent bore distortion and combustion blow-by.

An MLS gasket is composed of stacked and embossed multiple layers of full-hard stainless steel, which allow it to act as a "spring" between the head and block to maintain sealing stress against the castings. MLS technology is now the industry standard.

Diagnosing Cylinder Head Gasket Leaks

When a leak occurs externally it is easy to diagnose, as you will see the coolant, oil or carbon soot. But what if no external leak turns up? It is time to check for an internal one.

Dye Tests

The first and easiest check is a dye test. Use a special tool that looks like a turkey baster, to draw air from the top of the radiator. The air passes through a dye that changes color if exhaust gases are present. This is usually a reliable test, as long as the dye is fresh.

Alternatively, use an exhaust analyzer to sniff the same air. Be careful to not allow any coolant to enter your exhaust analyzer.

Cylinder Leak-Down Test

The most accurate test is the cylinder leak-down test. Bring each cylinder to TDC (top dead center) and pump compressed air into the cylinder via a leak-down tool while observing the coolant level in the radiator. When you pressurize the offending cylinder, it's hard to miss the reaction of the coolant.

The most accurate way to test for cylinder head gasket failure is with a cylinder leak down tester.

If there is no reaction in the radiator, remove the pressure, turn the engine until the next cylinder in the firing order is at TDC, and perform the leak-down test again. This test will diagnose failures that involve the coolant passages, but what about failure between cylinders?

An engine with compression leakage between cylinders will run poorly, yet some will continue to drive their vehicles, resulting in a very expensive engine repair. Aluminum cylinder heads have little tolerance for hot gases and extreme pressures: just a few miles of driving will ruin a casting and the cylinder block.

Once again, connect a leak-down tester, and bring the cylinder to TDC. Adjust the regulator for 100 psi going into the cylinder and read the second gauge showing the pressure held in the cylinder. Two adjacent cylinders that show abnormally high leakage will tell you where your potential leak is.

As a final set of checks be certain that:

The engine is in a proper state of tune,
The turbocharger control is functioning properly,
The EGR ports are clear and the system functions properly,
The cooling system is functioning properly, and
Exhaust backpressure is within limits.

All of these checks are to ensure that cylinder temperature and pressure are not abnormally high.

Why Do Head Gaskets Fail?

Today's OEM (original equipment manufacturer) design standard is 100,000-miles-plus durability, which requires improved manufacturing techniques, better quality control, and closer assembly tolerances to rack up the miles without incident.

Prior to the advent of engine controls, detonation and pre-ignition were frequent causes of head gasket failure. While these issues still arise, they are less common since head gaskets are capable of withstanding much higher combustion pressures and temperatures.

When a head gasket fails, investigate to determine the cause of the failure. Remove the old head gasket and measure the bore diameter from the intake side to the exhaust side of the gasket. If the gasket bore has grown .010" over standard, there's a good chance the engine has seen some detonation. Burning and carbon tracking can also be a good indicator of detonation.

Burning and carbon tracking on this cylinder head may indicate detonation.

Burning and carbon tracking from the cylinder head gasket side.

A damaged sealing ring on a gasket from an engine in which the cylinder head torque was not maintained.

You can gain a great deal of information from the witness marks on the face of the gasket and the corresponding deck surface. These marks are a direct reflection of surface finish. Read them carefully before installing a new gasket. The correct surface finish on the heads and block is critical to a good seal.

Replacing Gaskets

When replacing gaskets, pay special attention to head bolts and block preparation:

Be sure to clean and chase threads. (There is a difference between a tap and a thread chaser: Using a tap to chase the threads on your cylinder block will actually cut new threads instead of cleaning them.)
Lubricate bolts (and washers, if applicable) and the underside of bolt heads.
When it comes to torquing the bolts, always follow the OEM-recommend torque sequence and torque specifications to achieve the correct clamp load.
Most importantly, have your torque wrenches calibrated regularly. Since torque specifications are so important, an uncalibrated torque wrench could leave cylinder head bolts too loose or could possibly overtighten and break them.

Always use the OEM-recommended torque sequence and specifications when replacing a cylinder head gasket. Tap into your data 24/7 at: www.ChiltonPRO.com or www.ChiltonDIY.com.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Ford and Lincoln 4-Wheel Air Suspension

Jim Marotta — Thu, 11 Nov 2010 02:26:00 GMT

By Jim Marotta

History

Ford introduced 4-Wheel Air Suspension (4WAS) on the 1995 Explorer, and has since made it available on all three generations of the Ford Expedition and Lincoln Navigator. These big trucks weigh about three tons, so they already have a relatively comfortable ride using conventional suspension. Air suspension smooths that ride even further, but it's also used to increase off-road ride height and for load-leveling, which enhances stability when towing.

Today, air suspension still costs more than conventional suspension, but thanks to modern materials and electronics, it is simpler, reliable and offers more than just a comfortable ride.

Operation

The 4WAS is basically the same as conventional suspension. Up front, air struts replace the standard strut assemblies. In the rear, air springs replace the standard suspension's coil springs. All four air units have a normally-closed solenoid valve operated by the control module for adding or venting air pressure. Changing pressure not only changes ride height, it also changes spring rate. You can replace the solenoid valves on the rear air springs, but not the valves on the front air shocks.

The air suspension system consists of front air struts (center) and rear air springs (left) with shock absorbers (right).

The electric air compressor is different from the compressor on the Rear Air Suspension (RAS) system. It includes a built-in vent solenoid valve and a replaceable air dryer. The solenoid valve is also a spring-loaded safety valve that opens at 260 psi. A solid-state relay mounted below the headlight supplies battery voltage to the compressor.

In addition to the compressor's vent solenoid and the solenoid valve on each suspension unit, there are four more solenoid valves in the system. The front fill solenoid isolates the front air shocks from the rest of the system, and the rear-fill solenoid isolates the rear air springs. The front gate solenoid isolates the front air shocks from each other so the pressure between them does not equalize as the vehicle rolls in a turn. On smooth roads, this valve opens for a softer ride. Lastly, there is a pressure relief valve mounted on the frame crossmember near the rear height sensor. The control unit can use it to vent the rear air springs without having to open the rear-fill and system-vent solenoids.

On 2006 and earlier models, there are two linear ride height sensors that have a total stroke of about 3 inches. Sensor output is 0.25 volts at full extension and 4.75 volts at full compression.

On 2006 and earlier models, there are two linear ride height sensors, one mounted between the rear suspension panhard rod and the crossmember just forward of the spare tire, and one between the frame and the left front upper control arm. Even with only two sensors, the control unit is still capable of limited left/right height adjustments. The sensors have a total stroke of about 3 inches, which is how far the panhard rod and control arm move though the full 10 inches of suspension travel. Sensor output is 0.25 volts at full extension and 4.75 volts at full compression. Adjusting the sensor or the static ride height of the truck requires a scan tool for storing the new settings in the 4WAS control unit.

Later models have four identical potentiometer-type sensors, one at each corner, but they're permanently mounted to left- and right-side brackets so they can't be interchanged. The bracket is bolted to the frame, and a small ball stud link connects the sensor arm to the suspension arm.

On earlier models use the same control unit for the 4WAS, the Rear Air Suspension (RAS) system and the EVO Steering Control Module. Mounted in the instrument panel above the radio, it supplies reference voltage to the height sensors and controls the ground circuit of the compressor relay and the power circuit of each solenoid valve. Inputs come either directly from sensors or from other modules, including the front Generic Control Module (GEM) and the PCM. Inputs include vehicle height, vehicle speed, steering wheel position, brake and accelerator pedal positions, transfer case gear selection, transmission gear selection and door ajar signals.

On later models the Vehicle Dynamics Module (VDM; mounted above the parking brake handle) controls air suspension.

A manual air suspension switch turns the system off for service or long-term storage. On 1997-02 models, the switch is behind the front passenger side kick panel. On newer models, it's behind an access panel aft of the third-row seat on the driver side. That switch controls power to the control unit. When the switch is OFF, a warning light appears on the instrument panel with the ignition switch ON.

All of the air lines in the system are nylon. Two lines connect directly to the drier mounted on the compressor, one leading to the front fill solenoid valve and the other to the rear fill valve. The system uses quick-connect fittings throughout. You cannot repair or splice the air lines.

When the ignition switch is first turned ON, the control module runs a self-diagnostic test, storing or displaying any electrical or electronic problems detected as B or C codes.Any time a door or the rear hatch opens, the system will remember the height sensor readings. If you add or remove weight, the system will operate as needed to maintain that height. Once the doors are all closed and vehicle speed exceeds 10 mph, ride height will readjust as needed. The system's first priority is load leveling, but that's not all it can do.

The control unit can select from three different programmed suspension heights. "Trim" height is the normal ride height for paved road. Defined as trim plus 1 inch, "off-road" height engages automatically when the ignition switch is ON, the transfer case is in 4X4 LOW and the vehicle speed is less than 25 mph. Defined as trim minus 1 inch, "kneel" engages when vehicle speed is zero, all doors are closed and the ignition switch is OFF. Obviously the kneel height is to ease vehicle entry, and while one inch doesn't seem like much, it can make a difference. If the system detects a malfunction, the system will default to trim height, either by operating the compressor or by venting pressure as needed.

Servicing

As noted earlier, there is a switch to turn the system off for service. It should be turned off whenever you lift the wheels off the ground. Failure to do so can cause expensive damage, especially to the rear air springs. The only service required by the 4WAS itself is a visual inspection. Look for physical damage to the air springs, cut or crimped air lines or evidence of something rubbing the lines. There is no pressure sensor in this system, so the self-diagnostic test can't detect a leak. Symptoms of a leak include excessive compressor operation, failure to reach or maintain commanded height, and most commonly, a sagging rear end.

Leaking, dry-rotted air bags will cause excessive compressor operation, failure to reach or maintain commanded height, and most commonly, a sagging suspension.

A quick visual check for physical damage, like this torn airbag can make quick work of diagnosis.

Use soapy water to leak-check the fittings, and check the whole system with a smoke machine. Smoke is especially handy for finding a solenoid valve that's open when it shouldn't be, and vice-versa. Do not, under any circumstances, disconnect any fittings without venting the system first.

Check height sensors for damage and to make sure they're securely mounted. With the vehicle at trim height, sensor output should be 2.66 volts. Repairing, adjusting or replacing a sensor requires a scan tool to recalibrate the system.

Historically the most troublesome part of the system is the compressor. Failures tend to be gradual rather than catastrophic, and tell-tales signs are noise, rough running and excessive current draw. The sagging rear end noted earlier is what commonly drives owners to seek help. When replacing a compressor, techs often replace the solid-state relay too.

After replacing a sensor or the control unit, calibrate the control unit. This involves setting the mechanical ride height (with the system vented), and then using a scan tool to command specific functions through the control unit. The Ford NGS and the new IDS tools are best for the job, but there are some purpose-built aftermarket tools available from companies that sell air suspension parts.

This brings us to the final point. Since the compressor is the part that fails most often, techs often just install a new part and "get lucky." However if something else is wrong, the lack of proper tools, equipment, information, and parts can turn a potentially profitable job into an ugly situation. Should you decide to make the investment, there are several companies that offer everything you need to become an air suspension specialist.

While compressors (shown) are the part that fails the most frequently, a thorough diagnosis can save you money on replacing parts in the long run.

When you need to maintain or service a vehicle, get a valuable subscription to Chilton’s comprehensive service procedures, specifications, technical service bulletins, graphics, and wiring diagrams at www.ChiltonDIY.com or www.ChiltonPRO.com. A subscription, designed for professional technicians and for do-it-yourselfers, can save you many hours of frustration and pay for itself as soon as you use it.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Which Antifreeze is Right for Your Vehicle?

Jim Marotta — Thu, 29 Jul 2010 20:00:00 GMT

By Jim Marotta

Back in the day, no matter which brand you chose, antifreeze was green. The glycol-based formula contained silicates as corrosion inhibitors. You mixed the antifreeze 50/50 with water and poured it in the radiator. As the engine operated, the antifreeze performed its primary duties of carrying heat to the radiator, preventing freezing (hence the name) and protecting against corrosion in the cooling system. You simply changed the antifreeze at the prescribed service interval.

Today, with three types of antifreeze technology in a rainbow of colors, confusion abounds among automotive people and consumers alike as to what color antifreeze is best. The easy part is that most antifreeze manufacturers still make coolant with ethylene glycol (EG), a type of alcohol made from ethane. Manufacturers also make more environmentally friendly versions with less-toxic propylene glycol (PG), a similar compound made from propane.

Evolving Antifreeze

Inorganic Acid Technology (IAT) is the chemical basis for the traditional green antifreeze. IAT contains either EG or PG and is usually fortified with silicate or phosphate additives to make it compatible with metal cooling system components. The generally recommended replacement interval is every three years or 36,000 miles. The owner's manual or maintenance chart from ChiltonPRO.com and ChiltonDIY.com shows what the vehicle manufacturer recommends for each specific vehicle.

Inorganic acid technology is the chemical composition for the traditional green or yellow antifreeze (right). Organic acid technology is the orange coolant on the left.

Organic Acid Technology (OAT) is a Long Life Coolant (LLC) / Extended Life Coolant (ELC) widely used in Europe before its introduction in North America. OAT is usually EG. The generally recommended replacement interval is five years or 150,000 miles; find out what the vehicle manufacturer's recommendations are for your car or truck.

An example of an organic acid technology long life/extended life coolant.

Hybrid Organic Acid Technology (HOAT) combines IAT and OAT with nitrites. Antifreeze manufacturers often refer to it as "global," indicating on the bottle that it meets or exceeds the specification "G-05" for most vehicles newer than 2002 and "G-11" or "G-12" for Volkswagen and Audi. The generally recommended replacement interval is five years or 150,000 miles, always check your vehicle manufacturer's recommendations for your car or truck.

Why All the Different Coolant Formulations?

In the early 1980's Ford was working with antifreeze manufacturers to come up with a formulation to meet global needs. European countries had very hard water and since water is 50% of the antifreeze mix, water quality dramatically affects the overall mix. As European manufacturers were abandoning phosphate-based technology because phosphates tend to form scale, Japanese manufacturers were moving away from silicates, which tend to destroy water pump seals.

The first alternate coolants were hybrids combining carboxyl and silicate technologies. Ford started using them after extensive durability testing (more than 40 million fleet test miles on every vehicle platform that Ford had) in the early 1980s. At about the same time, Mercedes and VW were also using hybrid formulations.

In addition to better corrosion inhibitors for the global market, other issues precipitated formula change. Toxicity and environmental concerns are behind the use of PG rather than EG, while the promise of longer-lasting engine protection and less maintenance spur development of the newest formulations, such as Nissan's new blue coolant, which is designed to last ten years or 135,000 miles.

Does Antifreeze Break Down?

Engine antifreeze does break down, forming corrosive organic degradation products. Antifreeze buffering agents inhibit this corrosion. Since most antifreeze leaks out of the vehicle (according to the EPA, only 12% of antifreeze produced in the U.S. is recycled), most systems are "topped off" with fresh antifreeze, extending its life somewhat. How much depends on the type of antifreeze added.

Can You Mix Antifreeze Technologies?

The one universal coolant that all agree on is water. For best performance, water needs a little help. What happens when antifreezes are mixed? A lot of the confusion about mixing coolants stems from early work with carboxyl coolants. In an American Society of Testing and Materials (ASTM) test, mixing IAT and OAT coolants resulted in more corrosion than either antifreeze alone. Subsequent tests revealed a testing error: the corrosive environment occurred because the coolant was too dilute.

It is best to use the same type of coolant originally used in your car or truck, or the vehicle manufacturer's current recommendations. According to industry experts, if you do not know what coolant is in the vehicle and you top off with another brand, nothing bad is going to happen. Only when dilution rates border 50% is the effectiveness of each coolant's inhibitor package compromised. However, when mixing coolants, the recommended coolant change interval will degrade to that of the shorter-life coolant.

Proper Maintenance is Key

As with anything automotive, proper maintenance is the key to longevity. More important than the type of antifreeze you use is to maintain the cooling system properly by maintaining freeze point protection and proper coolant level. Almost all coolants work best at the ideal freeze point mixture, which for most parts of the country means a 50/50 antifreeze-to-water mixture. At this level, antifreeze protects to -34°F and boil-over protection to 257°F. In addition, maintaining proper freeze point protection ensures corrosion inhibitors are present at intended levels.

Maintaining the cooling system properly by maintaining freeze point protection and proper coolant level is critical. Here a handy tool provides coolant concentrations.

Vehicle manufacturers design cooling systems to operate full of antifreeze. A system that is constantly low on coolant can create an extremely corrosive environment due to the aggressive nature of the vapors of a glycol/water mix. These steam vapors are more corrosive than either fluid by itself. To check your coolant system capacity, simply refer to your vehicle's capacities chart at ChiltonDIY.com, ChiltonPRO.com, or your owner's manual.

If you choose to maintain your cooling system yourself, keep in mind that all types of antifreeze are poisonous. Animals and humans can be attracted by its sweet taste. Used coolant is extremely toxic and an environmental hazard, always recycle it properly.

Tap Water Won't Do

In almost every part of the country, tap water contains minerals such as magnesium and calcium that can form deposits in a cooling system, especially on the engine's hottest parts. The water you use to mix the antifreeze is critical. Premixed coolants are mixed at the factory with distilled water. Use distilled water, not tap or filtered water, when you refill any cooling system.

A system that is constantly low on coolant can create an extremely corrosive engine environment.

Coolant Keeps Working After the Engine Quits

Having the proper coolant level is still important after shutting off the engine. As the coolant stops flowing and the engine temperature increases dramatically, areas of localized boiling can send large shock waves through the engine wreaking havoc on components, especially those made of aluminum.

Which antifreeze do you use? Take the poll and tell us why in the Driver's co-pilot forum.

A subscription to ChiltonDIY or ChiltonPRO, with comprehensive maintenance charts and fluid capacity specifications, will give you all the information you need to keep your cooling system in top shape this summer.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Maintaining and Inspecting Your Automotive Lift

Jim Marotta — Fri, 16 Jul 2010 02:50:00 GMT

Fourth in a Series of Occasional Posts on Shop Maintenance

Photography and Story by Jim Marotta

Whether you use the in-ground or above-ground variety, a lift is one of the most important pieces of equipment in your shop and should be foremost on your inspection and maintenance list. Not only do malfunctioning lifts pose a safety concern, but it's difficult to perform your work without one.

Weight Capacity

Every type of lift requires specific safety procedures for safely lifting vehicles.

The most common type of vehicle lift is the two-post, above ground style. Weight capacity on these lifts can range from 7000 lbs. and higher, so consider the total lift capacity as well as the individual arm capacity (total capacity of the lift divided by the four swing arms) so you will not overload an arm.

Let us say a contractor's pickup truck is in the bay for an oil change. Our 10,000 lbs. lift (each arm lifting up to 2500 lbs.) can easily lift the 1-ton truck into the air. However, the truck's toolboxes and ladder racks make the rear of the truck heavier than the front. If the truck and tools have a total weight of approximately 9000 lbs. and the front/rear weight distribution on the truck is approximately 30/70 (3000 lbs. front and 6000 lbs. rear), we could overload the lift's rear arms and cause the lift to fail.

To ensure safety, manufacturers offer scales on lifts. The scales alert operators to overloaded lift conditions and avoid situations like the rear-heavy work truck scenario.

Proper Lifting

Once we know our lift can handle the vehicle we are lifting, we need to determine proper lifting points. A two-post lift engages the vehicle's frame or lifting points, so it is critical to know the specific lifting points for every vehicle.

Lifting a vehicle at the wrong points can damage components under the vehicle, such as brake lines, suspension components, or body parts. Failure to use the vehicle manufacturer recommended lifting points might cause the vehicle to slip off the lift, resulting in severe vehicle damage and personal injury.

It's critical to know the specific lifting points for every vehicle as specified by the manufacturer. (Photo: Jim Marotta)

As the vehicle's weight comes to rest on the lift arms, a mechanical safety lock system bears the weight of the vehicle at rest, rather than the hydraulic pressure of the lift pistons.

A mechanical safety lock system bears the weight of the vehicle at rest rather than the hydraulic pressure of the lift pistons. (Photo: Jim Marotta)

Maintenance and Inspection

Why is maintenance so important? What shop can afford to have jobs stacked up in the parking lot and employees standing idle? More importantly, you want to ensure the safety of anyone underneath or near your lifts.

How often should you inspect your lift? According to the Automotive Lift Institute (ALI), an association of automotive lift manufacturers promoting the safe design, construction, installation, service, and use of automotive lifts, an automotive lift should receive comprehensive annual inspections, or more frequently when specified by the manufacturer. In addition, ALI lists critical items to inspect every day:

Make sure the operating procedures, safety tips and generic safety material are accessible and legible.
Check for proper operation of the lift controls, restraints and locking devices.
Look for deformation or excessive wear of any of the lift structural components.
Inspect for deformation or excessive wear of other components such as hoses, electrical wires, drive chains, cables, or screws.

By keeping the lift components well lubricated, you can prevent excessive wear. Lubricate the lift cables with an all-purpose silicone lubricant. (Photo: Jim Marotta)

Look for damage or excessive wear on any of the lift contact points, which engage the vehicle during lifting.

The lift pads are where the rubber meets the vehicle. Prevent vehicle damage by replacing cracked or worn pads. (Photo: Jim Marotta)

Inspect for evidence of hydraulic or pneumatic leaks.

Oil seepage past the seals and down the hydraulic pistons is a good sign of a leak. (Photo: Jim Marotta)

Check for unusual noises, sudden movements, erratic operation or evidence of chips or filings during use.
Visually inspect for cracks or loose concrete around floor anchor bolts.

Follow the lift manufacturer's specified inspection and maintenance schedule and in addition, the ALI recommends these periodic inspections:

Confirm there is enough clearance around the lift.
Check all fastening devices for tightness, including the floor anchor bolts.
On lifts equipped with lateral synchronization or equalization systems, check the operation of the systems.
Operate the lift and check the operation of the positive stop and the lift locks.
On lifts with pumping units, confirm there is sufficient oil when the lift is fully raised.

Keeping the pump oil at the proper level is vital to smooth lift operation. Always check the level with the lift fully raised. (Photo: Jim Marotta)

With the lift loaded, stop the load at the midpoint of travel and observe that the load is being properly carried and that the lift does not change position.
With a representative vehicle on the lift, check the lowering speed.

By properly and consistently maintaining your equipment, and properly mounting vehicles on the lift, you will be taking care of one of your most important tools and paying yourself back many times over.

For more information on lifting points, just turn to www.ChiltonPRO.com. A subscription to Chilton's comprehensive service procedures, specifications, and wiring diagrams, gives you the information to do the job right the first time.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

How Hybrids Sip Gas, Save Money and Sweeten the Air

David Koontz — Wed, 16 Jun 2010 00:08:00 GMT

By David Koontz

A smug 2009 Toyota Prius, preens and greens in the desert.

More than one million hybrid vehicles quietly navigate America’s roads now, energizing proponents of this technology. Their popularity is no longer in question. Increasingly technicians see them in service bays, car enthusiasts learn how they work, and ecologically-conscious, if not economically-concerned drivers, wish they owned them. There is even unified government, industry and union support for the technology.

From the sweet air of the White House Rose Garden on May 19th, President Obama announced a deal brokered with the auto industry, United AutoWorkers union, the State of California (and other states that want to adopt more stringent standards), that would limit greenhouse gas emissions. The agreement would effectively reduce America’s oil consumption by 5% per year from 2011 to 2016, and increase the average fuel economy of new vehicles sold in America to 35.5 miles per gallon (mpg) by 2016. $50 billion in federal loans will entice automakers to meet that goal over the next seven years.

The current corporate average fuel economy (CAFE) stands at 25 mpg, so we have a lot of work to do to gain those additional 10.5 mpg. It will be met with a variety of technologies and consumer choices, including gasoline-electric hybrids, plug-in hybrids, diesel engine variants, engines that breathe better through more valves, superchargers, or turbochargers, vehicle downsizing, improved aerodynamics and weight-saving techniques.

A 2010 Honda Insight smiles at the road ahead.

Let’s look at how hybrids sip less fuel while belching fewer pollutants. Basically hybrids use battery power to augment gasoline engine power to propel the vehicle. When the vehicle is stopped in traffic, the gasoline engine is shut off. On full hybrids such as the Toyota Prius or Honda Insight, the battery propels the car until it reaches a certain speed or the driver stomps on the accelerator. As more speed is demanded, the gasoline engine restarts and both power sources propel the car. On a mild hybrid such as the Chevrolet Silverado or Saturn Vue, the gasoline engine is shut off when the vehicle is stopped, but it restarts as soon as the driver presses the accelerator. During hard acceleration, a combination starter/alternator provides additional electronic power.

Full hybrid technology usually adds about 10% to the vehicle’s price, while a mild hybrid adds a little less. So, is a hybrid vehicle worth the price differential with a similar sized, gasoline-engine vehicle? That depends on several variables: how much, how long and where you drive; the price of gasoline; insurance price differences; and whether you’ll need to replace the battery during your ownership of the vehicle. A mild hybrid increases fuel economy a modest 10-15% compared to a standard gasoline engine vehicle. But a full hybrid increases mpg by 25-30% compared to a similar-sized vehicle.

Gasoline in my neighborhood costs about $2.85 for a major-branded, standard 87-octane brew. A year ago the same fuel cost about $4.25. Most economists say gas will not get much cheaper and will likely cost more in the future. So, if we predict that the average price of gasoline will increase 10% per year, our sample hybrid vehicle yields 38 mpg while a similar gasoline engine version gets 29 mpg (about 30% more efficient), and we drive 15,000 miles per year, it would take about six years to pay back a vehicle price differential of about $2,500. That example considers fuel savings alone. Consider also that the 2009 federal tax incentive for purchasing certain hybrid vehicles can save you from $1,950 for a four-wheel drive Ford Escape or Mercury Mariner, for example, to $3,000 for two-wheel drive versions of the same vehicles. Now you could get your investment back in as little as one or two years.

This 2007 Ford Escape Hybrid has paid for its price premium already.

Are hybrid vehicles as reliable as standard gasoline engine models? In short, yes. Most vehicle manufacturers offer extended vehicle warranties to cover repairs and, other than the early Saturn Vues, hybrids have been very reliable. While most batteries are safely tucked behind panels on hybrid vehicles, we recommend following precautions such as these when working with the high-voltage battery and electrical circuits. As with any vehicle, when you need to maintain or service them, click on www.ChiltonDIY.com or www.ChiltonPRO.com to obtain a valuable subscription to Chilton’s comprehensive service procedures, specifications, graphics and wiring diagrams. These subscriptions, designed respectively for do-it-yourselfers and professional technicians, can save you many hours of frustration and pay for themselves as soon as they are used.

Now those are truly sweet deals.

David Koontz is the publisher of Chilton. He enjoys writing in all genres — from technical to poetry. In addition to a few domestic vehicles, he has owned, repaired and rebuilt some intriguing imported cars from makes such as Alfa Romeo, BMW, Fiat, Jaguar, Merkur, MG and SAAB. David has spent most of his life in southern California and resides there with his wife, Donna.

Kicking the Dirt to the Curb: The Never-Ending Battle to Keep Your Car Clean

Ryan Lee Price — Tue, 08 Jun 2010 17:44:00 GMT

Detailing: Part One

Story and Photography by Ryan Lee Price

Once the water evaporates, what is left are rings of crystals bonded to the paint and crusted with dirt.

The Shiny Side

On the first day, God created sunlight and dirt; four days later, He added bugs and birds. Some time after that, the car came along, and the four have been locked in mortal combat ever since. Like a game of Paper, Scissors, Rock: car kills bug; bug kill paint; bird kills bug; bird poops on car, kills paint (occasionally, car kills bird). It is a vicious cycle, and if you've been on a long drive anywhere out of town, you're familiar with the Technicolor insect necropolis on your windshield as a testimony to the damage it can do to your car's shiny side.

The main enemies of a pristine paint job are acid rain, bird droppings, alkaline-laden water drops (hard water) and plain old-fashioned dirt. Thanks to the industrial revolution, nitrous oxide and sulfur dioxide emissions from power plants, car exhaust and air pollution from industry are now trapped in rain water and dumped on your car during a storm. Called acid rain, it's basically a very dilute form of nitric and sulfuric acids. The sun dries the water droplets containing these acids and they are left behind to concentrate on your car's surface. Soon the concentrated acid penetrates the clear coat, dissolving the resin and forming a microscopic pit. Left untreated, the pit collects moisture and the concentrated acid can continue into the basecoat, destroying the pigment and eventually, the whole car.

Bird droppings contain a byproduct called uric acid. This alkaline, if left non-neutralized, can penetrate the clear-coat and cause damage similar to acid rain. Alkaline watermarks are all too familiar: What amounts to hard water spots are calcium and magnesium salt deposits on the paint after the water has evaporated. These white rings of minute crystals bond to the paint and cannot be re-dissolved by water; only a good degreaser can break up that relationship.

Every car enthusiast should have a cabinet in their garage just like this, with something to handle every car care situation that may arise.

Wash your car regularly. When the car is clean, unwanted moisture will dry up quickly, but when it's dirty, moisture accumulates with the dirt and causes corrosion. Use soap intended for a car's paint, not for washing dishes. You don't eat off of your car and you don't drive your plates, so leave the dishwashing soap in the kitchen. Wash your car in the shade and never in direct sunlight.

Wash the rims first (tires and windows last), and make sure they're cold before applying any rim cleaner. Hot wheels will burn the cleaner onto the rim and cause discoloration and/or permanent damage. Use a good quality cleaner designed for your car's rims. Don't rinse the rims and tires first, so you can apply the cleaner full-strength. Check the service information for special recommendations for your specific vehicle.

Use different a sponge for your tires (and any exterior rubber) and always start at the top of the car and wash down, so you're not dragging dirt over clean panels-plus the closer you get to the street, the dirtier the car is. Use a degreaser on tough areas, like oil spots, salt damage, and bug splatter.

Avoid any product that contains formaldehyde or any harsh preservatives, as they will harm tires.

When the car is mostly dry, apply a good tire dressing to the tires and bumpers. If you do this before you wax the car, and spray the dressing onto a rag, airborne droplets won't mar your freshly washed car. Avoid any product that contains formaldehyde or any harsh preservatives, as they will harm tires.

Instant detailer acts as a wax and gives you a great start toward a glossy shine.

While the car is still wet, mist it with instant detailer and chamois it dry. Instant detailer acts as a wax and gives you a great start toward that glossy shine. Never use a terrycloth towel, unless you love thousands of little scratches caused by dirt trapped in the loop pile. Many stores offer microfiber towels that work perfectly. At this point, the car doesn't have to be 100 percent dry, but just make sure you remove most of the water so it doesn't get a chance to bead up. Take a quick spin down the street and wipe off any water that has been blown from the mirrors, tires, or molding.

The Inside Story

Start by vacuuming the floor, the pockets, cup holders, anywhere that something can fall into (e.g., the glove box). For best results, remove everything from the car, from the floor mats to the coffee coupons in the console. Start with a small brush and get the dust and dirt out of the speaker grills and around the dash joints. To achieve professional results when cleaning carpets, always brush the carpet in one direction. Check the service information for specific recommendations as in this Technical Service Bulletin example from General Motors and Saab. Vehicle manufacturers may also have tips for leather care, check updated service information to learn what's recommended for your year, make and model.

Keep vinyl seats clean with a non-oil-based cleaner and a coarse towel to reach into crevices.

Clean Streaks

Never use a window cleaner that has ammonia, especially if you have a leather dash or trim. Ammonia overspray blocks the pores of the leather so it can't breathe properly, which will fog up your windows and leave streaks. Clean windows horizontally on the outside and vertically on the inside, so if it does streak, you'll know which side.

Now what you're left with is a clean car, complete with protection from the elements. However, like life, the concept of clean is fleeting, so keep this article handy for reference.

Cars that have been recently waxed or those that are somewhat new only need a good one-step cleaner/sealant/wax. If you wax the car often (every two to three months) use a quality carnauba wax or a quality cleaner wax. (Look for the second article of this series on Detailing for tips to achieve an amazing finish for older vehicles.)

Get comprehensive information about most any car on the road with a subscription to www.ChiltonDIY.com. Whatever your skill level, keeping your car clean is almost as important as keeping it running strong. To help reach that goal, keep your Chilton handy; it's especially tailored for you and your vehicle.

Not only is Ryan Lee Price a freelance writer specializing in automotive journalism and a former long-time magazine editor, he is part of the technical editorial team that provides content for most all of the ChiltonPRO and ChiltonDIY products. He currently resides in Corona, California, with his wife Kara and their two children.

Achieving Better Fuel Economy and High Performance with Gasoline Direct Injection

Jim Marotta — Tue, 26 Jan 2010 21:00:00 GMT

By Jim Marotta

Trying to choose between performance and economy is often a very difficult decision, and usually there has to be a compromise between the two. However, one technology is helping to power gasoline engines to new heights of performance, while pushing fuel mileage forward by leaps and bounds: gasoline direct injection. The photos below from Bosch illustrate the key elements of a gasoline direct injection system.

Back in the Day

Direct fuel injection is not a new idea. Diesel engines have always used the technology, which squirts fuel under high pressure into an engine’s cylinders rather than into the intake manifold. In a diesel engine, the process of injecting fuel directly into the combustion chamber at the top of the compression stroke initiates and controls combustion. The Robert Bosch Company perfected the modern mechanical injection pump for small diesels in Germany in 1927.

Bosch developed the first automotive direct injection system using gasoline, and Mercedes introduced it on the 1955 Mercedes Benz 300SL. Engine power was double that of its carbureted counterparts and allowed a top speed of up to 161 mph, making it the fastest production car of its time.

How Direct Injection Works

It might be easiest to see how direct injection works by comparing it to traditional fuel injection methods. With conventional fuel injection, injectors supply all cylinders with a mist mixture of air and fuel, averaging a constant 14.7:1 ratio, known as a stoichiometric mixture. Vacuum draws the mixture into the cylinder where the spark plug ignites it. The throttle valve determines how much of the air/fuel mixture enters each cylinder, keeping the mixture at an optimum 14.7:1 ratio. Lean air/fuel mixtures won’t ignite well, creating excessive NOx and hydrocarbon emissions which the catalytic converter must then capture and process.

In a direct injection engine, the injection nozzle is located inside the combustion chamber and injects a finer spray, like that from an atomizer bottle. Each solenoid-controlled injector has minute outlet holes which exude a fine mist. Injectors positioned to the side of each cylinder, aim the fuel into the cylinder, adjacent to the spark plug, and alongside the intake and exhaust valves.

Like an atomizer bottle spray, the fine mist generated by each solenoid-controlled injector's tiny outlet holes creates a well-atomized air/fuel mixture. Injectors spray fuel into the cylinders at pressures of up to 2,150 psi, about 35 times more intense than port fuel injection. (Courtesy of Bosch.)

A high-pressure fuel rail feeds each bank of cylinders using individual injectors and a fuel rail pressure sensor to help the powertrain control module precisely control fuel pressure. Some systems fire the injectors multiple times during one injection event at pressures of up to 2,150 psi, which is about 35 times more intense than port fuel injection.

Each bank of cylinders has a high-pressure fuel rail that feeds the individual injectors, and a high-pressure pump with a rail pressure sensor that helps the vehicle powertrain control module precisely control fuel pressure. (Courtesy of Bosch.)

When the injectors spray fuel into the cylinder, a relatively small, precisely-shaped volume of ignitable air/fuel mixture surrounds each spark plug. Areas inside the combustion chamber, but away from the spark plug, merely contain air or recirculated exhaust gas. This stratification of the charge allows the engine to burn mixtures with a much higher rate of air than conventional engines. The cushion of non-combustible gas around the combustion chamber also means less combustion heat to evacuate. This improves the thermal efficiency of the engine, increasing fuel economy.

To control injection valves, new common-rail injectors use a rapid-action actuator made of piezo crystals. Piezo package movement is transmitted non-mechanically and without friction to the rapidly switching nozzle needle. This doubles the injector's switching speed, allowing a more precise measurement of fuel injected, and thus reducing harmful combustion by-products. (Courtesy of Bosch.)

Since direct injection charge stratification works best at low and medium loads in the lower half of the engine speed range where traditional gasoline engines are least efficient, it allows direct injection engines to obtain up to 21 percent better fuel economy.

How Working Together Improves Performance and Economy

The future of direct injection involves coupling the system with other technologies, such as turbocharging and automatic engine stopping and restarting. By integrating multiple technologies, automakers can develop smaller, more fuel-efficient engines, while improving performance.

Turbocharging direct injection engines is a promising fuel economy technology. A turbocharged, direct-injection engine combines existing and proven technologies, allowing manufacturers to meet future emission standards using existing catalytic converters. Automakers can apply this technology across a manufacturer’s entire engine portfolio, including flexible fuel applications.

Other technologies maximize direct injection engine thermodynamics. In economy mode, an insulating blanket of air and recirculated exhaust gas helps keep heat away from the cylinder walls and head. In high-powered mode, the engine creates more heat. By controlling the operating speed of the water pump, especially during economy mode operation, a reduction in drag on the engine provides improved fuel economy. Variable intake and exhaust timing is especially efficient with gasoline direct injection and turbocharging systems. The variable engine timing enabled by camshaft phasing can optimize the combustion process. Also, valve overlap at low rpm can be adjusted by the engine controller to increase the turbocharger response, reducing turbo lag.

Servicing

With almost every manufacturer offering at least one direct injection engine, technicians should be seeing these vehicles in their bays for service.

“The biggest item to consider when servicing (direct injection) systems is the high voltage and fuel pressures the systems generate,” says Al Krenz, director of service for Bosch North America. A direct injection system typically will operate between 725 psi up to 2050 psi, so bleeding down the fuel system properly is important.”

“Always follow the manufacturer’s procedure to relieve the fuel system before performing any repairs to the system,” Krenz recommends.

Carefully diagnose the fuel injector voltage signals. High-pressure injectors typically actuate at approximately 70 volts and 10 amps, with the capability to rise over 120 volts.

As with diesel direct injectors, carbon can build up on the injector tip and interfere with fuel distribution and atomization. While typical port injectors produce a fuel droplet of approximately 165 microns, direct injectors atomize a much smaller fuel droplet size of only 65 microns, so even the slightest loss of fuel delivery will adversely affect engine drivability, power output, fuel economy and exhaust emission.

Direct injection and other complementary systems provide performance and economy by using very complex technologies. If you want to learn more about how specific direct injection and other technologies work, become a ChiltonPRO.com subscriber and receive all system service instructions.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Maintaining Your Shop's Computer Equipment

Jim Marotta — Wed, 25 Nov 2009 02:34:00 GMT

Third in a Series of Occasional Posts on Shop Maintenance

Photography and Story by Jim Marotta

A clean temperate climate and a consistent flow of electricity

Where would we be today without our computers? They power our shop management systems, provide our diagnostic and service information and enable us to order parts without picking up the phone. The only thing they require is a clean, temperate climate and a consistent flow of electricity. What most shop owners don't know is that the electrical power supplied from the wall outlet may not be stable enough to power their computers.

Depending on where your shop is located, power line disturbances strong enough to disrupt computer operation can occur frequently, resulting in hardware damage and more importantly, lost data. Unfortunately, equipment like your compressor and brake lathe are electrically "noisy" enough to cause disturbances.

Installing an Uninterruptible Power Supply (UPS) to the power supply for your computer equipment will not only provide backup AC power, allowing an orderly shutdown of computer equipment in the event of a power failure or blackout, but better units will also condition the electricity and allow for an uninterrupted supply of power.

The UPS system (left) used on this shop office computer provides backup AC power in the event of a power failure and conditions the electricity, allowing for a consistent supply of power to the computer. (Photography by Jim Marotta.)

Keep it clean

Shops are dirty, especially for computers. Use a computer vacuum or clean, dry, low pressure shop air monthly to prevent dust from accumulating on the power supplies, fans, heat sinks and vents. A gentle cleaning with appropriate cleaners will keep all surfaces of the computer, keyboard, mouse and screen fresh. Consider covering equipment when not in use.

Computers used on the shop floor require regular maintenance to prevent dust and dirt from accumulating on the power supplies, fans, heat sinks and vents. (Photography by Jim Marotta.)

Update and backup regularly

Now that the outside of the computer is maintained, let's turn our attention to the inside. For security and reliability purposes, update programs regularly. Install large updates, such as Service Packs, only after checking with software vendors to make sure there are no compatibility issues. Update your anti-virus software regularly, as the software is fully protecting the computer only if it is receiving updated virus signatures.

What would happen if you lost your building and all its contents to fire? You may be able to temporarily relocate but how would you contact your customers if all their information was on your (now melted) shop computer? Backup daily and weekly to insure none of your data is lost. Here is how to do it:

Contact all hardware and software vendors for documentation regarding which files to back up.
Perform daily on-site backups of all computers containing shop management and accounting software data files to correct accidental deletion of files, hardware failures, and system crashes.
Perform weekly backups of all computers containing shop management and accounting software data files and keep these discs in a secure place offsite to recover from catastrophic disasters such as fire or flood.
Both Microsoft and Apple provide free built-in backup utilities that are more than capable of satisfying the backup needs of all but the most complex computer systems and networks.

Every day the consequences of neglected maintenance appear on the vehicles that roll or are towed into the shop; the reasons for maintaining your shop equipment are equally clear. Protecting and maintaining our computers includes the simple tasks of keeping it clean and temperature-controlled, giving it an uninterruptible power source, and updating and backing up regularly. When you subscribe to Chilton for your automotive service, repair, and estimating information, Chilton takes care of the updates and backups for you. Just sign on to www.ChiltonPRO.com and www.ChiltonDIY.com, anytime.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

What You Need to Know About Tire Pressure Monitoring Systems

Jim Marotta — Wed, 18 Nov 2009 03:08:00 GMT

By Jim Marotta

A Tire Pressure Monitoring System (TPMS) is an electronic system designed to monitor the air pressure inside automotive tires. The system transmits real-time tire pressure information to the driver of the vehicle using a simple low pressure warning light in the instrument cluster.

Luxury becomes necessity

The first passenger vehicle to adopt TPMS was the Porsche 959 in 1986. Due to the increased use of Run Flat Tires, TPMS quickly became optional equipment for many luxury passenger vehicles, such as the Audi A8, Mercedes Benz S Class, BMW 7 Series, and the Chevrolet Corvette.

In the fall of 2000, following several fatal accidents involving underinflated tire failure and vehicle rollover, Congress signed into law the Transportation Recall, Enhancement, Accountability and Documentation Act (TREAD). This law mandates the use of a suitable TPMS technology to alert drivers of a severe underinflation condition of their tires. The law requires that all new vehicles produced for the US market after September 2007 have TPMS.

Direct and indirect TPMS

There are two types of tire pressure monitoring systems on the market today - direct and indirect.

Direct TPMS

Direct TPMS systems employ pressure sensors inside each tire to transmit air pressure information from inside the tire to a receiver and then to illuminate a light on the vehicle's instrument cluster. The system can identify simultaneous underinflation in all four tires in any combination with a typical trigger point of 25% below the recommended cold psi rating.

Direct TPMS systems employ pressure sensors inside each tire to transmit air pressure information from inside the tire to a receiver. (Courtesy of Toyota.)

High-line and low-line direct tire pressure monitors

Two types of direct tire pressure monitors are currently in use: high line and low line. High-line systems use low frequency transmitters near each wheel to force wheel-mounted sensors to transmit air pressure information when the ignition is switched on and then periodically as the vehicle is in motion. The transmitters are activated one at a time in sequence so that the system can determine the location of the wheel with low pressure. Some vehicles use only three transmitters to save money. High-line direct tire pressure systems tend to be used on higher-end models.

Low-line system sensors transmit their own signals. Since two or more sensors on a vehicle may transmit simultaneously, individual systems use different methods to ensure signals are received by the vehicle. On some systems the message is re-transmitted in a random or pseudo random pattern multiple times to reduce the effect of interference on communication. Another method is to simply transmit signals more frequently. When sensors detect a rapid change in pressure or a temperature that is too high, they start to transmit immediately. Low-line systems are used on the majority of vehicles due to their lower cost.

How indirect systems work

Indirect systems do not use physical pressure sensors but rather measure the apparent air pressure, by monitoring individual wheel rotational speeds, and other signals available outside the tire itself. An underinflated tire has a slightly smaller diameter than a correctly inflated tire and therefore has to rotate at a higher velocity to cover the same distance as a correctly inflated tire. The system functions in combination with wheel speed sensors for anti-lock braking systems (ABS), and electronic stability control systems (ESC).

Indirect systems do not use physical pressure sensors but rather measure the apparent air pressure, by monitoring individual wheel rotational speeds (Courtesy of Toyota.)

One disadvantage of indirect TPMS is that the driver must calibrate the system by pushing a reset button on the dashboard or through the onboard computer and if this is performed when any tire is in an underinflated condition the system will not report correctly.

TPMS Evolution

Recently, electronic systems manufacturer Johnson Controls introduced a new TPMS that uses an adaptive auto-learn capability to automatically detect the sensors and determine their positions. The system automatically calculates the positions of each tire sensor, analyzing signal input from the ABS and ESP control unit at the start of a journey. There is no need for a manual learning procedure, even after a tire change.

Techs can calibrate new sets of tires within two to three minutes. The system can also permanently save additional sensor IDs, increasing the calibration speed of a set of winter tires. After the system detects the saved IDs, the sensors calibrate quicker, even if these tires are mounted in different positions than before.

The system reports low pressure just as precisely for one individual tire as for all four tires. The sensor technology can even detect a minimal 1 psi change in pressure. While the system is direct-measuring, it is unlike comparable systems in that it only uses a single antenna which is integrated directly into the TPMS control unit. Because the receiver software calculates all of the information needed to analyze the signals, it requires no other components apart from the tire sensors.

Avoid service mishaps

On direct TPMS systems, any service requiring the dismounting and mounting of tires can damage a sensor unit, including new tire installation and flat repairs. Other common service mishaps include inappropriate tool use, incorrect valve stem sensor installation and torque, and not replacing the nickel-plated valve core and rubber grommet in the valve stem.

Incorrect valve stem sensor installation and torque, and not replacing the nickel-plated valve core and rubber grommet in the valve stem can cause problems with the sensor. (Courtesy of Toyota.)

Another issue that seems to be a common concern is the weather, specifically in the climates of the northern US. The harsh winter weather affects the aluminum sensors causing them to oxidize on the inside.

Any service that requires the dismounting and mounting of tires can damage a sensor unit, including new tire installation. Proper tire machine technique is critical to not damage the sensor. (Courtesy of Toyota.)

Most indirect TPMS systems require resetting to recalibrate the system. A reset is typically required after adding air to a low tire, after changing or servicing a tire, or after rotating the tires on a vehicle. Finding the reset button and determining the reset procedure are the only difficult points to service.

With so many different reset procedures, it's important to make sure you are using the right procedure for the vehicle being serviced. Since GM has over 10 different procedures depending on application, consult www.ChiltonDIY.com or www.ChiltonPRO.com, for the proper procedure and the location of the reset button. You can access Chilton's comprehensive service procedures, specifications, and wiring diagrams online 24/7.

While TPMS systems offer increased safety to drivers through low pressure warnings, they are not meant to be a substitute for proper tire pressure maintenance. How frequently should you be checking tire air pressure? Certainly any time the ambient temperature changes dramatically, and follow the manufacturer's maintenance intervals and specified inflation pressures. Get them at www.ChiltonDIY.com or www.ChiltonPRO.com.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Why You Need to Maintain Your A/C Recovery and Recycling Machine

Jim Marotta — Sun, 15 Nov 2009 03:28:00 GMT

Second in a Series of Occasional Posts on Shop Maintenance

Photography and Story by Jim Marotta

It's a sweltering August afternoon and an overheated customer comes in saying the A/C isn't working. Earlier this week you convinced him to pay for needed A/C system maintenance. What went wrong? Could it be deferred maintenance on your refrigerant recovery and recycling machine? Recovery and recycling machines have come a long way from their simple beginnings. However, with more complexity, there is more to go wrong.

Back to Basics

Surprisingly, basic maintenance on today's complex recycle/recovery machines has not changed that much. You still need to change the filters regularly and change the vacuum pump oil, if the machine has a vacuum pump. Also, you must purge the air from the tank. Draining the refrigerant oil recovery bottle after each use is a required daily maintenance task.

Changing the filters, O-rings, oils, and leak checking the unit can usually be done in about 1 to 1-1/2 hours with the parts costing under $100. Some machines will even prompt you when it is time for maintenance. Even the older machines use an hour meter that indicates usage between maintenance intervals.

When it comes to changing the filters, most are easily changed with common hand tools. Some even have knurled fittings and do not require hand tools at all. Changing vacuum pump oil is just as simple. While each manufacturer has a specified procedure, most are simply a drain and refill. Changing out the oil ensures efficient operation, reducing the amount of time the machine takes to evacuate the system. Another item, keeping a machine clean, is simply a matter of wiping up spilt oil or covering the machine to keep dust out of the electronic circuit boards.

Replacing a typical filter is a matter of loosening the tubing nuts and replacing the filter. Photography by Jim Marotta.

With repair bills for recovery/recycling machines averaging $400 and up, and the cost of a new automatic machine averaging $2500, plus the lost revenue from the absent machine, you can see that maintenance is the answer.

Common problems and failures

Oil drain bottle is not drained after each recovery - If the oil bottle is not drained and allowed to fill up, it will allow liquid refrigerant to enter the compressor. The compressor is made to pump gas and when liquid is allowed to enter the compressor it will damage the valves. The only repair at that point is to replace the compressor.

A twist of the wrist after each service keeps oil from building up and causing damage to the machine. Photography by Jim Marotta.

Air in the refrigerant - When air finds it way into your storage tank it can be troublesome: it can shut the machine off due to excessive pressure and slow down the recovery process. You can tell if air is present by comparing the pressure and temperature in the storage tank to the manufacturer's table. Follow the manufacturer's instructions and purge the air regularly; you don't want air in your customer's A/C system and you don't want it in your recycler.

The machine is left dirty or dusty - Keep it free of dust to protect the circuit boards in the machine. Too much dust can cause the circuit boards to short circuit and fail. Some of the boards are $500 to $800 just for the part.

A buildup of dust on circuit boards may cause them to short circuit and fail. Photography by Jim Marotta.

Dirt drawn in through the compressor air intake will eventually cause accelerated wear on this unit. Photography by Jim Marotta.

Tank valves leak - When you have a tank valve leak it is usually due to overtightening or overopening the valve, which damages the valve seats. The tanks are required to meet DOT certifications and if a valve is replaced in the original tank or if the tank is older than five years send it out to be recertified, just like a welding cylinder. The cost of a new tank is most often less than or about the same cost of replacing the valve and sending it out or recertification. You can get a new tank on the machine a lot quicker.

Excessive force when closing a service valve wears out the valve seat, causing the valve to leak and refrigerant to escape. Photography by Jim Marotta.

Hoses and O-rings leak - Inspect hoses regularly and replace them if they are bad. If working with pressure in the line, the refrigerant will most likely leak out like air through a leaky fitting on a shop air fitting. However if you are working with vacuum in the lines you may experience the symptoms of a compressor or vacuum pump failure. Symptoms include the unit not pulling down adequately. If the machine is in recovery, this will fill your recovery tank with air pressure and eventually should shut the machine down.

Why replace O-rings? Take a look at this comparison. The one on the left is new. The one on the right is swelled and could allow refrigerant to escape or air to enter the system. Photography by Jim Marotta.

The other common problem with O-rings, and this one is much more overlooked, is people tend to overtighten the hose connections especially when the O-rings have deteriorated and are in need of replacement. This causes the O-rings to over-compress and seal off the flow of the hose, resulting in slow or no charging, recovery, and evacuation depending on which hoses are affected.

This is not a reliable seal under pressure or vacuum. Under pressure refrigerant will leak out and under vacuum air will leak in. Photography by Jim Marotta.

Another byproduct of overtightening the O-rings and not replacing them is that small pieces of the O-rings may break apart creating fragments which tend to get stuck in the valve cores and solenoids causing recycler malfunction.

Keypads fail - Keypads will wear out with use, but take care not to use screwdrivers or other items to push the keys.

Scales require calibration - Overcharging or undercharging a system usually results in a comeback and a hot, angry customer. Calibrate the scales frequently.

Save yourself the aggravation of comebacks caused by neglected maintenance of your recovery and recycling machine. Good tools, available when you need them are essential to your professional image and your business. Don't neglect your service information. Subscribe to ChiltonPRO and access the information you need when you need it. For those who only need information on only one or a few models, ChiltonDIY is available.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

The Air Compressor - A Most Valuable Tool

Jim Marotta — Tue, 20 Oct 2009 03:05:00 GMT

First in a Series of Occasional Posts on Shop Maintenance

Photography and Story by Jim Marotta

The Compressor Room

Few pieces of shop equipment are used as regularly as air compressors. To ensure that an air compressor continues to run smoothly day after day, install compressors in a clean, well-ventilated area. Some shops place their compressor in a (clean, well-ventilated) room that's apart from the general shop area, often referred to as the compressor room. This special room may also include an external clean air intake for the compressor.

Protect your Investment

As a safety precaution to protect equipment that is run off the air compressor, install a filter, regulator, lubricator, and/or gauge in your system. Attach these units to the line no less than 10 to 12 feet from the air compressor. This distance allows the air to semi-cool before going through the filter, allowing the filter to do its job better.

To insure a constant supply of clean, regulated air, install a filter in your system. If you use air tools that require lubrication, add a lubricator or oiler. (Photography by Jim Marotta.)

Maintain Correct Pressure

A pressure gauge is essential for maintaining pressure within tool manufacturers' recommended levels. Incorrect levels can cause safety hazards and impair tool performance. The pressure gauge can also help detect any leaks which may be in the lines.

Extend the Lifespan of your Tools and Equipment

Install lubricators (often referred to as oilers) between the filter and the machine the air compressor powers. Lubricators feed oil directly into the air line, constantly lubricating your air tools. This lubrication can significantly extend the lifespan of your tools and equipment.

Keep it Cool

Use an air dryer to help cool the compressed air after it leaves the compressor on its way to your tools and equipment. This cooling of the air lowers the dew point, which turns any water vapor in the air into liquid. The dryer then removes the moisture from the air line. There are a few different types of dryers on the market today, so be sure to discuss with your supplier which one best fits your shop's needs based on what you will be using the compressed air for on a daily basis.

Stay Cool By Keeping It Clean

Keep the entire air compressor clean, as dirt can act as an insulator and cause the unit to run hotter than necessary. Under normal use, temperatures inside an air compressor can exceed 400° F. Anything you can do keep this temperature from escalating will help your air compressor run better and last longer.

Compressor Maintenance

Proper compressor maintenance includes: 1. Draining the water from the main tank, 2. Changing the oil, 3. Inspecting the drive belts, and 4. Changing the air filter.

1. Drain Water from the Main Tank

Drain water from the main air tank on the compressor daily (or if used less frequently, any day you use it). Drain the tank manually or through an automatic device that opens the bottom drain for a specified period of time each day.

Draining water from the tank daily prevents a buildup of moisture inside the tank that may cause premature tank failure. It also helps to keep the air supply clean and dry. (Photgraphy by Jim Marotta.)

2. Change the Oil

Change the oil in your compressor regularly. A low oil level can cause the pump to work harder and run hotter. Change the oil at least every 6 months or in severe applications, every 2 to 3 months.

3. Inspect the Belts

Perform a safety inspection on your shop's air compressor regularly. Inspect the drive belts for any signs of wear. If you find damage to either belt, always replace both belts at the same time. Replacing the belts as a matched set maintains balanced tension from the drive to the pulley.

4. Change the Air Filter

Change the air filter on your compressor regularly. Many filters can be cleaned and reinstalled. A dirty filter causes the pump to work harder and run hotter.

Cleaning the air filter periodically helps the compressor to run cooler. (Photography by Jim Marotta.)

Removing a caliper piston from its bore is one of the many uses for an air compressor in a shop. Follow Jim's tips to keep this most valuable tool cool, extending its life as well as the lifespan of your air tools.

Like your air compressor, ChiltonPRO is one of a shop's most valuable and often used tools; while ChiltonDIY is here to guide the do-it-yourselfer and enthusiast. Like any good tool, key information when you need it saves you time and money. A good tool repays its cost many times over, so tool maintenance is an investment in yourself. Continue to invest in yourself by keeping your Chilton subscription up-to-date.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

How to Restore Old Bolts

Ryan Lee Price — Mon, 12 Oct 2009 17:51:00 GMT

Story and Photography by Ryan Lee Price

If your wheel bolts are original, go to your car, pull one out and take a look at it (just one!): It's a simple threaded iron bolt likely covered in what appears to be a thick layer of dirt and/or grease. Upon closer inspection, the dirt and grease are probably hiding a destructive coating of rust. Rust causes iron to fail, and failing in an area as important as wheels isn't a good idea no matter the condition of the rest of your car. Instead of sitting hunched over your workbench for hours with a tiny wire brush scraping away at 16 to 28 little wheel bolts (or any number of other dirty bolts on your car), consider a different approach that will add not only life to your old bolts but beauty as well. Several companies offer vibrating tumblers similar to rock polishers that will clean and polish small parts with very little effort.

The tumbler system has a capacity of 5 lbs. and is very effective in removing rust, grease and dirt on most any parts you can fit in there.

Here's a closer look at a few of the wheel bolts we had around the garage that needed some sprucing up.

On the left is the pyramid green rust cutting media; for roughly $20, the 2.5 lbs. lasts quite a while. While on the right is the dry shine media for finer polishing.

There are a few ways to give your smaller parts a clean, fresh look, from professional powder coating to chrome plating, but tin-zinc plating kits are popular for small jobs when details count. Electroplating uses electric current (in this case from a battery) to pull small amounts of metal from the charged tin-zinc anode bar, through an electrolyte solution, and onto the negatively charged piece to be plated. It is simple, safe, non-toxic, and easy to use.

The kit includes everything you'll need to start plating out of the box (except for batteries), including gloves and safety goggles.

Place the positively charged anode bar into the solution and attach the negatively-charged piece into the solution for five to six seconds, or until there is a gray film over the part. The included metal polish will bring the piece to a beautiful shine.

Here is an example of the progress of our efforts, from an original bolt through the replating and the tumbler systems to the final product. From left to right, the first bolt is untouched and covered with 35 years of dirt and grime; the second bolt is after five hours in the rust-cutting green media; the third after an hour of dry shine media, and the last bolt is after a protective coat of tin-zinc electroplating was applied.

If you are one to spend the time and trouble of media tumbling and zinc-plating old bolts to a fancy shine for your latest project, you're probably also the sort of do-it-yourselfer who takes pride in the smallest of details. This is where a subscription to www.ChiltonDIY.com would prove to be just as handy as the wrench in your toolbox. With comprehensive service procedures, specifications, graphics and wiring diagrams just a click away, you'll have everything you'll need at your fingertips.

Why is America Holding Out on the Metric System?

Ryan Lee Price — Mon, 05 Oct 2009 18:08:00 GMT

By Ryan Lee Price

We measure tire pressure in pounds per square inch, engine displacement on modern cars in liters, while gas comes in gallons. Speedometers show both miles per hour and kilometers per hour, and the majority of U.S.-made vehicles contain a hodge-podge of bolts with varying specs, both metric and standard. Why has the U.S. held out so long against the metric system when it is embraced by 99 percent of the world? Expense? Tradition? Unimportant?

A Measured Pace

Only three countries-Burma (Myanmar), Liberia, and the United States-have yet to adopt the International System of Units (aka metric) as their official system of measurement. Though the U.S. has been increasing its use of metric units for many years, the pace has accelerated in the past three decades. In the early 1800s, the U.S. Coast and Geodetic Survey (the government's surveying and map-making agency) used meter and kilogram standards brought from France. In 1866, Congress authorized the use of the metric system in this country and supplied each state with a set of standard metric weights and measures.

In 1875, the United States solidified its commitment to the development of the internationally recognized metric system by becoming one of the original seventeen signatory nations to the Treaty of the Meter. The signing of this international agreement concluded five years of meetings in which the metric system was reformulated, refining the accuracy of its standards. The Treaty of the Meter, also know as the "Metric Convention," established the International Bureau of Weights and Measures (BIPM) in Sèvres, France, to provide standards of measurement for worldwide use.

Confusion about weights and measures in 19th Century United States is well displayed in this advertisement showing the different ways states measured a bushel.

Measure for Measure

In 1893, the United States adopted metric standards, developed through international cooperation under the auspices of BIPM, as the fundamental standards for length and mass. The meter and the kilogram have defined our customary measurements -- the foot, pound, quart, etc. -- ever since. The General Conference of Weights and Measures, the governing body that has overall responsibility for the metric system, and which is made up of the signatory nations to the Treaty of the Meter, approved an updated version of the metric system in 1960. This modern system is called Le Système International d'Unités or the International System of Units, abbreviated SI.

In 1968, Congress authorized a three-year study of systems of measurement in the U.S., with particular emphasis on the feasibility of adopting SI. The Department of Commerce conducted a detailed U.S. Metric Study, and the final report of the study: "A Metric America: A Decision Whose Time Has Come," concluded that the U.S. would eventually join the rest of the world in the use of the metric system of measurement. The study recommended that the United States implement a carefully planned transition to predominant use of the metric system over a 10-year period. Congress passed the Metric Conversion Act of 1975 "to coordinate and plan the increasing use of the metric system in the United States." The Act, however, did not require a 10-year conversion period. The act initiated a process of voluntary conversion and charged the newly-established U.S. Metric Board with "devising and carrying out a broad program of planning, coordination, and public education, consistent with other national policy and interests, with the aim of implementing the policy set forth in this Act." The American public largely ignored the efforts of the Metric Board and in 1981, the Board reported to Congress that it lacked the clear Congressional mandate necessary to bring about national conversion. Due to this apparent ineffectiveness, and in an effort to reduce Federal spending, the US disestablished the Metric Board in the fall of 1982.

Congress, recognizing the necessity of the United States' conforming with international standards for trade, included new encouragement for U.S. industrial metrication in the Omnibus Trade and Competitiveness Act of 1988. This legislation amended the Metric Conversion Act of 1975 and designates the metric system as the "preferred system of weights and measures for United States trade and commerce." The legislation states that the Federal Government has a responsibility to assist industry, especially small business, as it voluntarily converts to the metric system of measurement.

A world map showing the metrication of its countries, color-coded by year of conversion. Data source: U.S. Metric Association.

Not-So-Temporary Measures

This legislation required Federal agencies, with certain exceptions, to use the metric system in their procurement, grants and other business-related activities by the end of 1992. While not mandating metric use in the private sector, the Federal Government seeks to serve as a catalyst in the metric conversion of the country's trade, industry, and commerce. Regardless of these steps, a resource like this one is needed to compare the differences and similarities between U.S. and metric fasteners and will be for some time.

Metric *vs.* US Standard (SAE)
Inches	Metric	Inch Size
.1875	NE	3/16"
.1969	5mm	NE
.2187	NE	7/32"
.2362	6mm	NE
.2500	NE	1/4"
.2756	7mm	NE
.2812	NE	9/32"
.3125	NE	5/16"
.3150	8mm	NE
.3543	9mm	NE
.3750	NE	3/8"
.3937	10mm	NE
.4330	11mm	NE
.4375	NE	7/16"
.4724	12mm	NE
.5000	NE	1/2"
.5118	13mm	NE
.5512	14mm	NE
.5625	NE	9/16"
.5906	15mm	NE
.6250	NE	5/8"
.6299	16mm	NE
.6693	17mm	NE
.6875	NE	11/16"
.7078	18mm	NE
.7480	19mm	NE
.7500	NE	3/4"
.7874	20mm	NE
.8125	NE	13/16"
.8268	21mm	NE
.8661	22mm	NE
.8750	NE	7/8"
.9055	23mm	NE
.9375	NE	15/16"
.9449	24mm	NE
.9843	25mm	NE
1.000	NE	1
NE = No full integer equivalent.

Does Your Fastener Measure Up?

The Society of Automotive Engineers, or SAE creates technical standards. Now an international organization, SAE standards advance mobility engineering throughout the world. More than 9,000 volunteer engineers, and other qualified professionals from around the world develop the standards by consensus. The standards apply to fasteners, such as nuts and bolts, as well as washers, torque-tension procedures, steels, hardenability, and many others.

For more information, click here to learn about U.S. and metric measurements and their conversions. Confused? The U.S. government periodically issues a Handbook of US customary measurements.

What is the future of the metric system in the United States? More and more, US manufacturers are using components from international sources, forcing its consumers to have both standard and metric tools readily available. How long until a ½-inch wrench becomes obsolete, if ever? Chilton is a valuable source for service procedures, specifications, graphics and wiring diagrams via subscriptions to www.ChiltonDIY.com and www.ChiltonPRO.com.

Automotive Nuts and Bolts: How to Keep the Miniature Marvels Working at Top Efficiency

Ryan Lee Price — Wed, 16 Sep 2009 19:42:00 GMT

By Ryan Lee Price

Strip a thread? Break off a bolt head? Nothing can halt a project on its heels quicker than a broken bolt or fastener, stripped nut or rounded off capscrew. The weakest point of any design is where two pieces come together, specifically, where the bolts meet the metal, and more so if that bolt is incorrectly tightened. Bolt (and/or nut) failure on a vehicle can have potentially disastrous consequences, so it is important to closely follow the tightening sequences for the specific vehicle.

A threaded fastener generally fails in one of three ways: 1) through the threaded section of the fastener; 2) thread stripping of the external thread; or 3) thread stripping of the internally threaded member.

Stress and Friction: Why Bolts Fail

The vast majority of fastener failures occur because of the first reason, failure through the bolt thread. Under static loads, the area most stressed determines the strength of the thread. When tightening a bolt, the shank sustains a direct stress, due to the elongation strain, together with a torsion stress of tightening due to the torque acting on the threads. If the values of these stresses, added to the frictional conditions that all bolts encounter, become greater than the design characteristics of the bolt, it simply bends, twists, or snaps off completely.

Stripping Saps Thread Strength Gradually

In many designs thread stripping is a problem where tapped holes are required in low tensile material, such as magnesium and aluminum. In general terms, thread stripping tends to be gradual in nature but greatly diminishes the usefulness of a fastener. The following factors all have an important effect on the strength of a thread: 1) The variation in the dimensions of the thread, (such as pitch and diameter of the thread); 2) Tensile and shear strength variations in the material for both the internal and external threads; 3) Known as nut dilation, the radial displacement of the nut or tapped component reduces the strength of the threads. The force on the fastener (like a wedging action) generates a radial displacement which reduces thread strength; 4) The effect of radial displacement, which causes bending of the threads; 5) Production variations in the threaded assembly, such as slight hole taper or bellmouthing, affect thread strength, creating essentially, a lemon bolt.

Solutions for Damaged Threads

Several methods of repairing damaged threads are available on the market today and these involve the same principle-drilling out stripped threads, tapping the hole and installing a pre-wound insert -- and it makes welding, plugging and oversize fasteners unnecessary.

Thread Repair Inserts

A kit usually supplies two types of thread repair inserts: a standard type for most inch-coarse, inch-fine, metric-coarse and metric-fine thread sizes and a spark plug type to fit most spark plug port sizes. Typical thread repair kits contain a selection of pre-wound threaded inserts, a tap (corresponding to the outside diameter threads of the insert) and an installation tool. Spark plug inserts usually differ because they require a tap equipped with pilot threads and a combined reamer/tap section. Most manufacturers also supply thread repair inserts separately plus a master kit containing a variety of taps and inserts plus installation tools.

Before repairing a threaded hole, remove any snapped, broken or damaged bolts, or studs. Use penetrating oil to free frozen threads. Remove the offending item with locking pliers or with a screw or stud extractor. Once the hole is clear, repair the thread as follows: Drill out the damaged threads with the specified bit. Drill completely through the hole or to the bottom of the blind hole. With the tap supplied, rethread the hole to receive the threaded insert. Keep the tap well oiled and back the tap out frequently to avoid clogging the threads. Screw the thread insert onto the thread installation tool until the tang engages the slot. Screw the insert into the tapped hole until it is a quarter to half turn below the surface. After installation break the tang off with a hammer and punch.

If you don't have the time or ability to pull the head or install heli-coils to repair a damaged thread, try a back tap-style tool similar to the ones shown here. The slim profile slips into the striped hole and then expands to the exact size, and if you apply a grease to the tip, it will catch filings and debris. These are available in 10, 12, 14 and 18mm for a wide variety of applications. Photography by Ryan Lee Price.

It is a good idea to consider applying antiseize compound to most all nuts and bolts during your projects. It prevents corrosion and resists moisture. Photography by Ryan Lee Price.

How to Torque Bolts with Minimal Crosstalk

Thread damage is just one way the force a bolt withstands is expressed. Notice what happens when force or torque is applied to a bolt: When tightening the outer bolts of any multi-bolt part (like on a cylinder head, for example), the joint under the bolts compresses, naturally. Subsequently tightening the middle bolts not only compresses the joint directly under the bolts but also slightly compresses the joint under the two previously tightened bolts, leading to a loss of preload in these bolts. Preload is the tension placed on a bolt by the nut.

Because all bolts cannot be tightened simultaneously, tightening one bolt in a group of bolts affects the preload in other previously tightened bolts in the group by compressing the joint. Such effects are called elastic interactions or sometimes, bolt crosstalk.

Crosstalk affects joints that are significantly less stiff than the bolts, such as joints involving gaskets. The best way to control crosstalk is to use a carefully thought out tightening sequence.

Tightening Sequences Reduce Crosstalk

The following two tightening sequences reduce bolt preload variations due to elastic interactions. They minimize the preload scatter within a joint and possibly avoid damage to the gasket. The first method is a simple cross tightening, similar to the method of tightening a wheel. Picture the bolt pattern like a clock—tighten noon, then six, then nine, then three. The second method is for linear patterns, this 2008 Honda main bearing or the cylinder head torque sequence for a 2003 Dodge Ram 1500. Start with the center-most bolts and spiral outward, either clockwise or counter-clockwise. If the joint is critical, it would be wise to consider specifying a multiple-pass tightening sequence. The preload caused by the tightening of the other bolts in the joint with such a sequence is reduced when each bolt is tightened more than once.

Use a Torque Wrench

Assure proper installation of a fastener by using a torque wrench and always follow the proper torque specifications as listed in ChiltonDIY or ChiltonPRO, valuable sources of Chilton’s comprehensive service procedures, specifications, graphics and wiring diagrams. Torque wrenches come in various designs and most automotive supply stores carry a variety to suit any need. Use a torque wrench whenever a specific torque value is given for a fastener.

Applying force to one area affects adjoining areas, so follow appropriate torque sequences and remember, the general rule “if you are using the right tool for the job, you should not have to strain to tighten a fastener,” applies here.

In the best of times, working under the hood can be rewarding, satisfying and even fun, but in the worst of times, it can be downright frustrating, as unforeseen incidents can pile on time, resources, and stress to any project. A subscription to www.ChiltonDIY.com or www.ChiltonPRO.com, is the right tool to grab -- designed respectively for do-it-yourselfers and professional technicians to save many hours of frustration, build confidence in your garage or shop and immediately pay for themselves.

How to Recognize Metric and SAE Bolts

Ryan Lee Price — Tue, 08 Sep 2009 21:16:00 GMT

Story and Photography by Ryan Lee Price

Since Ford’s introduction of the Pinto engine in the ’70s and Cadillac’s badging of the 1970 Eldorado as an 8.2L engine, the use of the metric system has become more prevalent in domestic vehicles, and odds are good that the majority of those domestic vehicles on the road today have more metric fasteners than the inch-size (SAE) type. While the size may be similar, the pitch of the threads will be different, so it is important to be able to recognize the difference between metric and standard fasteners. This is most important when a manufacturer changes style or size during the production run.

There is nothing in greater quantity on your car than the nuts, bolts and screws that help hold it together.

Fastener manufacturers identify bolts and capscrews by type, length, major diameter, pitch (threads per inch), length of thread, class or fit, material, tensile strength, and the wrench size needed to tighten them. All these variables match the fastener to the particular application for which it was designed. A bolt which is too long might interfere with other parts and won’t utilize the full design of the bolt. A capscrew which is too soft might snap off before the proper torque is reached. The wrong thread size will strip out the nut or receiving hole and cause a host of new problems.

Bolts and capscrews are not all made of the same quality material nor is the tempering the same. Markings are stamped on the face to indicate the bolt type, and specifically, show the tensile strength of the fastener, or the amount of pull an object will withstand before breaking. Generally, a fastener with more tensile strength accepts more torque before breaking, but to avoid breaking bolts, a torque chart is most helpful.

Bolt manufacturers use a variety of methods for marking the classifications of their products.

Bolt Markings

Tensile Strength

No markings on the bolt head indicate a low carbon steel bolt with a tensile strength 64,000psi or less. These are "soft bolts," commonly referred to in mechanical engineering circles as a Grade Two or Three bolt. Soft bolts have an indeterminate quality and are commonly used in light manufacturing. A bolt head with three raised slots “stamped” on it indicates a Grade Five, medium carbon steel, tempered; it is a minimum commercial quality fastener with a tensile strength of 105,000psi. Four raised slots means a Grade Six, medium carbon steel, quenched/tempered, medium commercial quality, with 133,000psi rating. Six raised slots is a Grade Eight, medium carbon alloy steel, quenched, tempered, 150,000psi, and is the best commercial quality. A Grade 12 has eight raised slots surrounding an oval, and is a special alloy steel, quenched and tempered. A Grade 12 is recommended for critical use and competition purposes.

If you’re stuck with a pile of unsorted bolts, instead of pulling out every wrench in your toolbox, get one of these simple sizing tools from most any hardware store.

Coarse and Fine Threads

For American bolts (standard inches) there are two basic types: The Unified National Fine thread and Unified National Coarse thread variety. Thread pitch, or the distance between the crest of a thread to the same spot on the crest of the next thread, helps determine the type; the smaller the pitch, the greater number of threads per inch. Use a thread-pitch gauge to determine the number of threads-per-inch. Use coarse-threaded hardware in cast iron and aluminum because it won’t strip the mating hole as easily as fine threads. Coarse-threaded hardware screws in and out more quickly and is less subject to stripping and galling (the threads ripping particles of metal from each other thereby damaging both threads). Fine-threaded hardware tends to take more torque and, as a result, has a slightly better holding capability.

Metric and SAE

Fortunately, fastener manufacturers mark metric bolts differently than SAE bolts. Manufacturers emboss International Standards Organization (ISO) metric bolts larger than 6mm in diameter with either “ISO M” or “M” on top of the head. In addition, manufacturers stamp most metric bolts with a number on the bolt head, such as 4.6, 5.8 or 10.9. This number has nothing to do with the size, but does indicate the relative strength of the bolt: the higher the number, the stronger the bolt. Manufacturers mark some metric nuts with a single-digit number to indicate the strength, and some emboss the "M" and strength grade on the flats of the hex.

The Clock-Face System

An alternate way of designating strength grade is the clock-face system. Fastener manufacturers mark the external faces of the bolt and/or nut with a dash at the appropriate hour mark corresponding to the relative strength grade. One dot at the 12 o'clock position indicates a grade under 12, while two dots found at the 12 o'clock position is Grade 12 and over. Manufacturers indicate specific grades with tick marks: a tick mark at six o’clock is a Grade Six bolt, eight o’clock is Grade Eight and a tick mark at two o’clock (with two dots at noon) means a Grade 14.

Size Designations

Fastener manufacturers identify the size of a metric fastener differently than an SAE fastener. As an example, a metric fastener size is: M12 x 2. This means that the major diameter of the threads is 12mm and that the thread pitch is 2mm (there are 2mm between threads). ISO classes metric threads by the distance between the threads, and the distance between threads does not exactly correspond to number of threads per inch (2mm between threads is about 12.7 threads per inch).

Save Time and Aggravation

Time spent organizing bins of nuts and bolts into types and sizes will save a lot of time on the other end, not to mention the headache caused from mistaking a metric bolt for a U.S.-spec bolt.

Steering clear of the pitfalls of automotive service saves time and aggravation. Ryan Price and his colleagues at Chilton aim to help you steer clear. Whether you need procedures and specifications for one vehicle, (www.ChiltonDIY.com), or for many vehicles (www.ChiltonPRO.com), a subscription will give you full access to TSBs and Recalls, maintenance, service and repair information, as well as ASE test preparation and estimating.

Expect the Unexpected with Electronic Stability Control

Jim Marotta — Wed, 02 Sep 2009 03:17:00 GMT

Story and Photography by Jim Marotta

“A truly stable system expects the unexpected, is prepared to be disrupted, waits to be transformed.” ~ Tom Robbins

It seems that James Bond might drive this car, with a system that unites the Anti-Lock Brake System (ABS) and Traction Control System (TCS) to monitor the vehicle’s motion and make corrections to stabilize the car and prevent skidding. But many vehicles today deliver us to our destinations while practically driving themselves. Eventually, vehicles sold in the U.S. will be required to have such a system.

German Origins

Electronic Stability Control (ESC) is a refinement of the original Anti-Lock Brake System (ABS) co-developed by Bosch and Mercedes-Benz, and introduced on the Mercedes-Benz S-Class in 1978. ESC first appeared on the 1995 Mercedes Benz S-Class.

After several rollover crashes during magazine testing of the new 1996 Mercedes Benz A-Class compact car, Mercedes recalled and retrofitted 130,000 A-Class cars with ESC. This produced a significant reduction in crashes and the number of Mercedes vehicles fitted with ESC rose significantly. The remaining vehicle manufacturers quickly followed by developing their own versions. To date, there are more than a dozen different systems in use.

Expect More

In September 2007, due to governmental and public demand, the National Highway Traffic and Safety Administration (NHTSA) proposed a new rule requiring all new light-duty vehicles sold in the United States to be equipped with ESC by the 2012 model year. This rule became Federal Motor Vehicle Safety Standard (FMVSS) No.126. As of 2009, close to 74 percent of new vehicles have ESC as standard equipment, and an additional 13 percent offer it as an option.

How ESC Works

Modern ESC systems are autonomous units which do not require driver operation. The ESC control unit receives inputs from several sensors to determine desired versus actual vehicle trajectory.

ESC compares the driver's intended vehicle direction to the actual vehicle direction by using sensors to measure steering angle, lateral acceleration, vehicle rotation (yaw), and individual road wheel speeds. (Courtesy Robert Bosch Corp.)

Steering Wheel Angle Sensor: commonly a potentiometer or an optical sensor with two sensing elements positioned at 90 degrees to each other. The potentiometer provides data to the ESC control unit about the direction the driver intends to steer. When replaced in service, the sensor must be calibrated with the wheels in the straight ahead position.

Lateral Acceleration Sensor: a solid state sensor that signals the ECS control unit when the vehicle is being subjected to g-forces in a turn. The signal voltage varies according to the amount of g-force. 4WD and AWD vehicles also incorporate a Longitudinal Acceleration Sensor.

Vehicle Rotation (Yaw) Sensor: a solid-state sensor that mimics a gyroscope to measure the vehicle’s angular velocity around its vertical axis. The output is usually in degrees per second. The angle between the vehicle's heading and its actual movement direction is called slip angle, which is related to the yaw rate. The Yaw and Lateral Acceleration sensors are usually combined into one centrally mounted unit.

Wheel Speed Sensor: a magnetic sensor and rotor (tone) or in more recent systems, an active wheel speed sensor, which provides individual wheel speed data to the ESC control unit. These sensors are also used for ABS control.

The ESC control unit continuously monitors the wheel speed sensors to determine wheel slippage. At the same time the lateral acceleration sensor determines acceleration g-force and yaw sensors measure vehicle rotation around its vertical axis. From this data, the control unit calculates the actual movement of the vehicle about all three axes, comparing it multiple times per second with the desired direction.

When the ESC control unit detects loss of steering control, it applies the brakes to individual wheels and brings the vehicle back in line with the driver's commanded direction. Some systems also can reduce engine power or operate the transmission to slow down the vehicle. (Courtesy Robert Bosch Corp.)

When the control unit detects loss of steering control, such as when the vehicle understeers, oversteers, skids or hydroplanes, and the input values do not correspond to the actual vehicle direction, the system reacts without any action on the part of the driver, by reducing engine power and/or applying the brakes on only the appropriate wheel to restore vehicle stability. The resulting rotary movement of the vehicle counteracts the skidding condition within the limits of the vehicle and keeps it on the desired course.

a) Understeer b) Oversteer

a) During an understeer condition, when the front wheels do not follow the trajectory the driver is trying to impose while taking the corner, ESC applies the inside rear brake to prevent the front of the vehicle from plowing forward. b) During an oversteer condition, when the rear wheels do not track behind the front wheels but instead slide out toward the outside of the turn, ESC applies the outside front brake to prevent the rear of the vehicle from spinning out. (Courtesy Insurance Institute for Highway Safety)

Although most ESC systems use similar sensors and hardware, the way systems are programmed to respond varies once a loss of control is detected. Some ESC systems activate sooner than others or slow a vehicle more quickly when a driver begins to lose control.

Manufacturers calibrate stability control systems to provide different safety and handling characteristics in the same way each car has a unique chassis balance: no two systems are identical. Manufacturers safety calibrate some stability control systems and provide an early intervention while others allow a subtle, more progressive degree of control that only intervenes at high cornering forces.

The Plot Thickens

Recently, system co-developer Robert Bosch Corporation started production of a new version of its Electronic Stability Program (ESP)® which integrates the lateral acceleration and yaw sensors inside the electronic control unit, eliminating the need for separate wiring harnesses to connect the sensors.

Previously, Bosch placed the electronic control unit of the ESP in the engine compartment, attached directly to the ABS system's hydraulic modulator. In order to integrate the sensors in the control unit, Bosch adapted the sensors to the considerably higher ambient temperatures and to the vibrations that occur when the brake control system intervenes. The result reduced vibration and optimized balance in a three-point installation of the hydraulic unit. This installation also ensured that driving on extremely poor roads would have no influence on system function.

A new version of Bosch’s Electronic Stability Program (ESP)® integrates the lateral acceleration and yaw sensors inside the electronic control unit, eliminating the need for separate wiring harnesses to connect the sensors. (Courtesy of Robert Bosch Corp.)

Another challenge was the lateral-acceleration sensor’s orientation. Bosch placed existing sensors installed in the vehicle interior precisely at right angles to the direction of travel. By integrating two acceleration sensors that measure precisely at right angles to each other, the hydraulic modulator, which must still be installed horizontally, can be positioned around its vertical axis as desired. Now the ECU calculates the vehicle’s acceleration precisely, based on the known installation location and the signals from both acceleration sensors. With the precise vehicle acceleration information, the ECU can measure the vehicle's longitudinal acceleration.

Prepare for the Unexpected At Your Service

Even something simple like a wheel alignment may require special equipment when servicing vehicles with ESC. For example, a scan tool may be necessary to perform the steering angle sensor calibration. If not performed correctly, it can result in trouble codes being set because the steering angle sensor is reading that the vehicle is turning even though the front wheels are pointed straight ahead.

While ABS is not a new invention, technicians should be aware that to properly perform a brake fluid flush (either as preventative maintenance, or as part of a brake service) a scan tool must be used to open and close the solenoid valves to flush all the old fluid. This is particularly important in ESC-equipped vehicles as the ESC solenoids operate independently of brake pedal application.

In a related situation, during routine brake service, carefully examine wiring harnesses and connectors to determine their condition and proper routing. If a wiring harness is pulled too tight during suspension movement it can result in a damaged wire or connector, thus setting a wheel speed sensor trouble code.

For those still using dynamometers to perform IM 240 emissions tests, it should be noted that vehicles equipped with ESC systems will not function on a 2-wheel dynamometer. When only the drive wheels spin, the logic circuit in the traction control module interprets this as "slippage" (similar to accelerating on ice). The traction control module will reduce throttle position, making testing impossible.

You don’t need 007’s connections (or his car) to obtain more intelligence on specific ESC systems. You can become a ChiltonPRO or ChiltonDIY subscriber and receive full ESC system service instructions.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

A Quick and Easy Way to Bleed a Brake System

Ryan Lee Price — Fri, 21 Aug 2009 21:23:00 GMT

Story and Photography by Ryan Lee Price

One of the most important steps in making the brakes safe and reliable for everyday use is to properly bleed the system. The concept behind bleeding a brake system is to remove any air bubbles left in the lines. It is essential to bleed the brakes before operating the vehicle if you replace the master cylinder, wheel cylinders, or any of the brake lines or if you are introducing fluid into the system.

Brake fluid, much like water, cannot be compressed; which is why a hydraulic braking system is so effective and efficient.

First off, how does a simple dual-circuit hydraulic foot-brake system work?

When you step down on the brake pedal and it feels soft, spongy or weak, odds are good that air is in the system (or fluid pressure is low). Even though we call the brakes a hydraulic system, it doesn’t use water, but instead, uses a brake fluid with properties similar to water. Like water, brake fluid is incompressible, meaning that it will never take up less space under pressure (only one gallon of fluid will fit into a one-gallon jug), whereas air under pressure compresses into a smaller volume. Apply this principle to the brake system and when a bubble of air is stuck in the lines, the air bubble compresses instead of passing along the force of the pedal to the wheel cylinders via the master cylinder.

As you press down on the pedal, you actuate the master cylinder which increases pressure in the lines. In a typical system, the master cylinder has two pistons, one for the front and one for the back brakes. Hydraulic pressure allows the wheel cylinders (one located at each wheel) to squeeze the brake shoes against the drums (or discs). The reservoir refreshes the system, and as you release the brake pedal the pistons in the master cylinder relax, and the fluid

Of course, bleeding the brakes isn’t a salve for all of the problems with any brake system, but if bleeding the system doesn’t fix a weak pedal, there is probably a leak somewhere. Since brake systems vary, such as with this 2001 Buick Regal system, versus the system for a 2007 Ford Explorer, let’s demonstrate the concept of bleeding the braking system with a simple classic Volkswagen, a 1971 Super Beetle.

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It is easier to access the wheels and the system if you jack the car up and safely rest it on jack stands. Keep it on level ground, as well. This way, judging the reservoir level is more accurate.

If the reservoir is full, but the liquid inside is questionable (dirty or littered with debris), make sure to flush the system before disconnecting it or making repairs. Be careful, as brake fluid is highly corrosive and will turn a beautiful paint job into bare metal in moments.

Start by filling the reservoir until it is approximately one-half inch from the bottom of the neck, and during the bleeding process check the level after each wheel. If it goes dry, you’ll have to refill and start all over again.

Below the bolt for the wheel cylinder and above the hard brake line is the bleeder valve, which may be different on different models. On the Volkswagen, it is covered by a small rubber grommet and kept secure by a 7mm bolt.

There’s no need to purchase a fancy brake bleeding kit, as an old soda bottle with a length of fuel line fed through the cap and into a small amount of brake fluid will work well. Make sure the fuel line fits snugly over the bleeder valve.

Just as brake lines can contain air, air can also be present in the master cylinder. Loosening the fitting for the master cylinder rear circuit and having an assistant pump the pedal a couple of times forces the air bubble. After a few pumps, have the assistant hold the pedal down while you tighten the fitting.

After clearing the master cylinder, start with the wheel farthest from the master cylinder, which would be the rear passenger wheel. Attach the reserve bottle to the bleeder valve and loosen the 7mm bolt one-half turn.

While the valve is open, have the assistant slowly depress the brake pedal and hold it. Watch the soda bottle for bubbles. When the bubbles stop, close the valve. Repeat this process a couple of times for each wheel, or until the bubbles stop.

Complete this same process on all four wheels, working your way closer to the master cylinder. In addition to pumping the brakes, the assistant can let his or her foot slip off of the brake pedal, forcing a sudden surge of fluid into the lines ... and the air out.

The idea behind dipping the other end of the bleeder line in the fluid-filled bottle is so when the pedal is released, fluid is sucked back into the system from either the in-car reservoir or up from the bottle.

Once the bubbles are completely gone from the wheel line, tighten the bleeder valve and move onto the next one.

Once you think you’ve got everything just right, lower the car to the ground and give it a test run in a safe location. Check the pedal play, as there should only be 5 to 7mm of play before the pushrod begins to activate the master cylinder. If it is not within acceptable play, adjust it by loosening the clamp bolt and moving the pedal’s stop bracket.

Since brake bleeding and pedal adjustment procedures can vary for different vehicles, stop by www.ChiltonDIY.com and bring your maintenance questions to a reassuring rest.

Not only is Ryan Lee Price a freelance writer specializing in automotive journalism and a former long-time magazine editor, he is part of the technical editorial team that provides content for most all of the ChiltonPro and ChiltonDIY products. He currently resides in Corona, California, with his wife Kara and their two children.

Fighting Rust: Some Chemistry and Solutions

Ryan Lee Price — Sat, 08 Aug 2009 21:32:00 GMT

Story and Photography by Ryan Lee Price

Left unchecked and in constant contact with oxygen and moisture, rust will eventually convert all available iron into… more rust.

Life On Earth Thanks to ... Rust?

Approximately 4.6 billion years ago, when the solar system birthed, hydrogen (H), carbon (C), nitrogen (N), oxygen (O) and iron (Fe) swirled around in space. As soon as these atoms emerged, iron reacted with oxygen, forming iron oxide. This prevented carbon or nitrogen from reacting with oxygen and forming carbon dioxide and nitrogen oxide, both of which are hazardous gases for human beings. Instead, carbon and nitrogen reacted with hydrogen to form methane and ammonia, and these two compounds eventually formed DNA, which led to all life on Earth.

Just Add Water

The 117 elements on the periodic table that are known to exist in this universe make millions of combinations to form the many thousands of materials that surround us every day. Most of those molecules are carbon and silicon based—the building blocks of life—but the air in Earth’s atmosphere contains not only oxygen, nitrogen and hydrogen and a host of other elements, but also lots of moisture. Without moisture (and sunshine), Earth would experience no weather and iron wouldn’t rust.

Types of Steel Used in Vehicles

Low carbon steel, which is an alloy made up of iron and traces of carbon (less than 0.1 percent), accounts for 90 percent of all steel production. Generally speaking, the average car body is made from this kind of steel. The carbon content in iron has a significant impact on the characteristics of the final alloy, as there are approximately 3,000 types of steel, from stainless steel (think DeLorean) to aluminum (the hood of a 2008 Chevrolet Tahoe Hybrid). Some of today’s cars, such as the Volvo XC90, BMW E60, and Porsche Cayenne, are using boron (B) in their steel alloys, creating a much more durable steel.

Iron + Water = Rust

Chemical reactions happen all the time, as each element in the periodic table meets other elements, like a big singles’ bar. Sometimes the elements get together and sometimes they don’t, but when it comes to iron and oxygen, they always bond (which is the reason why iron in your diet helps promote good circulation). Add moisture to the mix, and rust is the result:

Two parts of iron (Fe) plus three parts of oxygen (O) equal Fe₂O₃, or iron oxide, which is found naturally in roughly 16 forms and is relatively harmless by itself.

But unfortunately, oxygen carries with it, by way of the moisture in the air, water (H₂O), which reacts with iron to form rust. The oxygen and moisture combine with iron to create a hydrated iron oxide— Fe₂O₃ x H₂O—on the surface of the metal. This is rust: cancer in the automotive world.

This type of iron oxide— Fe₂O₃ x H₂O—is bulky and porous, and it allows more oxygen access to the iron surrounding it, causing similar chemical reactions. The resulting reactions of water, oxygen and iron, if allowed to continue, will completely convert the remaining iron to hydrated iron oxide, which is weak and flaky and will compromise the structural integrity of the original metal. Only iron-based alloys (like steel and chrome) rust, while all other types of metals (like copper and zinc) corrode.

How do you stop rust? Just keep oxygen away from your car. No oxygen, no chemical reaction, no problem. However, since oxygen makes up roughly 21 percent of the air we breathe, and there is moisture in that air, rust happens. Even on the sunniest days and over the hottest deserts, air is full of water.

Assuming the problem has gone beyond preventative measures, the only way to further keep oxygen and moisture from reaching the iron and creating rust is to mechanically or chemically remove all the existing rust before the surface can be sealed again. If any rust remains and paint is applied over the surface, enough moisture and oxygen still exist on the metal to continue the rusting process (i.e., paint bubbles).

There are four main methods for dealing with rusty metal: mechanical removal, specialty paints, acids, and chemical converters. With the exception of chemical conversion, many procedures for removing rust involve toxic chemicals and/or require special equipment.

The mechanical removal of rusted panels can take on several forms, from merely sanding and grinding to cutting out and replacing a section of rusted sheet metal.

Mechanical Removal—The most common methods of removing rust are by using grinders, wire brushes, sandpaper and sand blasting. For minor rust, sandpaper will effectively remove surface rust (or steel wool on chrome), while sandblasting will take care of more developed rust.

One of the most popular ways to eradicate existing rust and to prevent new rust from forming is specialty paints that create a non-porous surface that cannot be penetrated by oxygen or moisture.

Special Paints—A few paints on the market claim the ability to encapsulate rust. They have chemical structure that dries to an incredible rock-hard, non-porous finish that won't chip, crack, or peel, and it prevents rust from recurring by protecting metal from further exposure to moisture.

Acids—Acids (specifically phosphoric acid) dissolve the rust and leave behind a thin oxide coating on the surface. It is important to rinse off the metal before the acid begins to attack the metal. This is similar to paint stripping. In this process, the metal is dipped in large tanks of caustic soda. After the paint is dissolved, the metal is put in another tank of alkaline solution and the rust is removed through electrolysis. An over-the-counter multi-purpose phosphoric acid based cleaner and pre-paint conditioner will achieve similar results.

Chemical Conversion—Blacksmiths were the first to discover that when they coated their tools with oil and then heated them in an oven their tools weren’t susceptible to rust. Typically, chemical converters are solutions or primers designed to be applied directly to a rusty surface to convert residual rust on steel surfaces to harmless and adherent chemical compounds that provide a protective film (usually phosphates) on the metal surface that protect against rust.

Subscribers to www.ChiltonDIY.com never get rusty, they keep learning how to protect the things they love.

Not only is Ryan Lee Price a freelance writer specializing in automotive journalism and a former long-time magazine editor, he is part of the technical editorial team that provides content for most all of the ChiltonPro and ChiltonDIY products. He currently resides in Corona, California, with his wife Kara and their two children.

Tire Pressure 101

Jim Marotta — Tue, 04 Aug 2009 22:00:00 GMT

Story and Photography by Jim Marotta

The automotive tires that keep our vehicles rolling down the road are rated by the manufacturer to handle specific loads at a predetermined air pressure. By keeping the air pressure in the tire optimized, both tire performance and fuel economy are maximized.

So what makes it so difficult to keep tire pressure consistent? According to tire industry data, 85 percent of all tire air pressure losses are the result of slow leaks that occur over a period of hours, days, or months. Tires typically lose air pressure through natural leakage or permeation at a rate of about 1 psi per month. In addition, tire manufacturers say that seasonal climatic changes result in air pressure losses of 1 psi for every 10° F decrease in the ambient temperature.

Here in the Northeast part of the country, differences between summer and winter temperatures average about 46° F, resulting in a net loss or gain of nearly 5 psi in air pressure. This great variation is enough to dramatically affect handling, traction, and durability of the average tire if the pressure is not adjusted seasonally. Even temperature fluctuations during the day can make a dramatic difference, as variations between nighttime and daytime temperatures in this part of the country can average 20° F and result in pressure changes of over 2 psi.

No matter where you are, temperature fluctuations, whether large (think: Arizona in the summer) or small, as in balmy Mumbai in winter, will affect your tire pressure, so careful monitoring is important.

During a February 2001 survey, crash investigators measured tire pressure on each vehicle coming into a gas station and compared the measured pressures to the vehicle's placard pressure. They found that about 36 percent of passenger cars and about 40 percent of light trucks had at least one tire that was at least 20 percent below the placard pressure.

According to US government statistics, 660 people die and 33,000 are injured every year due to tire pressure-related accidents. In addition, improper tire pressure costs an extra $3.7 billion in fuel annually and every year causes, 4.5 million tires to need replacement before their designed lifespan.

The Mechanical Gauge

In the beginning was the tire pressure gauge, a simple device that, once applied to the valve stem of a tire, would indicate the air pressure inside a tire. The most ubiquitous of its many variants was (and still is) the pen-style gauge. Here's how it works:

Inside the pen (tube) shaped body, a piston made of soft rubber is forced by air entering the gauge against a calibrated spring which runs the length of the tube. On the opposite end of the tube is a stop. The distance the piston travels is relative to the pressure in the tire.

Mechanical tire pressure gauge components.

While using this type of mechanical gauge is simple, keeping the tires at correct pressure is more difficult. First, there must be a convenient supply of dry, vapor-free compressed air to inflate the tire. This is not a problem for the technician in a shop but may present a problem for the some motorists. Second, the gauge in use must be accurate. Gauge accuracy may affect correct pressure by 3 psi or more. Last, most vehicle owners do not check tire pressure nearly enough. An American Automobile Association (AAA) poll suggests that 85 percent of motorists do not know how to check tire pressure.

The Tire Inflation Pressure Label

So by now you are convinced of the value checking your tire pressure regularly. The first step is to determine the correct tire size and air pressure for your vehicle. If you have a subscription to www.ChiltonDIY.com or www.ChiltonPRO.com, you can just check with Chilton for the proper specification. For vehicles built after 2002, a placard and label must be located on the driver's side B-pillar. If a vehicle does not have a B-pillar, then the placard and label must be placed on the edge of the driver's door. If the vehicle does not have a driver's side B-pillar and the driver's side door edge is too narrow or does not exist, the placard or placard and label must be affixed to the inward-facing surface of the vehicle next to the driver's seating position. Most people are not able to locate or do not even know about their vehicle's information placard and yet, this small sticker contains key information about the vehicle, including the correct tire pressure for the front and rear tires. In most vehicles, the owner's manual will direct you to the vehicle information placard's location.

The tire inflation pressure label contains gross vehicle weight, correct tire size, speed rating, and cold inflation pressure information.

Tire Pressure Monitoring Systems

Tire pressure monitoring systems (TPMS) report real time tire pressure information to the driver of the vehicle and are mandatory on all vehicles produced for sale in the US since September 2007. So if the vehicle is equipped with it, why not let the TPMS take care of the tire pressure? There is one very good reason: many of these systems only alert the driver to low tire pressure when the tires lose 25% of their pressure. As we stated earlier, pressure losses of only 5 psi (15 percent on a tire inflated to 32 psi) can dramatically affect the handling, the traction, and the durability of the average tire.

Are these three tires underinflated, overinflated or inflated to proper pressure? It is hard to tell the difference just looking at them. We underinflated the tire on the left by 5 psi, the center is at its proper pressure of 32 psi, and we overinflated the right tire by 5 psi.

Nitrogen for Tires

We normally inflated tires with a combination of gases comprised of Nitrogen (N2), Oxygen (O2) and Argon (Ar), commonly known as “compressed air.” Unfortunately, the compressed air we use to fill our tires contains moisture. Moisture reacts with the rubber compounds in the tire, causing them to break down and lose their strength and durability. This results in the natural leakage or permeation at a rate of about 1 psi per month we discussed earlier.

Oxygen also corrodes aluminum and steel wheel components and ages the thin layer of rubber inside the tire whose function is keeping air away from the carcass. As the thin layer of rubber or inner liner ages, more air molecules can pass through it, causing pressure losses.

More and more, driving aficionados along with a new crowd of environmental advocates are turning to nitrogen to fill their tires. Nitrogen gas is slower than air to leak from tires because the N02 molecule is larger, resulting in a more consistent tire pressure, cooler operating temperature, and longer tread life. In addition, nitrogen does not oxidize tire components, reducing rim and wheel corrosion.

Michelin, BF Goodrich, Goodyear and many more tire manufacturers support nitrogen inflation for its ability to better retain pressure for a longer period of time.

Whether you fill your tires with compressed air or nitrogen, how frequently should you check tire pressure? Certainly any time the ambient temperature changes dramatically, but we recommend you follow the manufacturer’s maintenance intervals and specified inflation pressures. Get them in ChiltonDIY or ChiltonPRO.

A muscle car enthusiast and drag racer, Jim Marotta is a freelance automotive writer with more than 20 years experience in the automotive industry.

Does Your Car's Name Mean Something? How to Decode Import Car Model Names

Ryan Lee Price — Thu, 16 Jul 2009 21:01:00 GMT

By Ryan Lee Price

Would you drive a Ford Pastelogram? How about a Mongoose Civique or a Utopian Turtletop? These were suggestions from modernist poet Marianne Moore, solicited by Ford’s David Wallace, manager of marketing research for Ford’s proposed “E-car project” in 1955. Wallace’s rationale in choosing Moore to help name the new line of cars was, “who better to understand the nature of words than a poet?” In the end, Edsel was chosen, and that’s the end of that chapter.

Though the traditional methods of car naming are still prevalent in today’s cars (thanks mostly to domestic manufacturers), it seems that more and more imports are resorting to alphanumeric combinations to identify the latest models. Even though it may look like someone merely chucked a handful of chromed numbers and letters on the trunk lid, for some, there is a method to the madness. The rules below aren’t necessarily hard and fast, as exceptions are just as common.

Acura

Acura switched from names to letters in the mid 1990s, and all but one of its models’ monikers are meaningless. (Photo by Ryan Lee Price)

The two- and three-letter combinations are completely made up with one exception. The NSX was in development in the 1980s, while Acura was still using names in its line; it stands for New Sports eXperimental.MDX and RDX each contain an X which is now ubiquitous for an SUV.

BMW

This 3-series BMW has a 3.0L engine and is fuel injected, with the “i” being more of a tradition than a selling point. (Photo by Ryan Lee Price)

The first number is used to describe the size and cost of its models, while the following two digits indicate engine size. The BMW 325i has a 2.5L engine, while the 330i has a 3.0L engine, etc. The “i” at the end indicates that it is fuel injected, and diesel-fueled models in Europe have a “d” instead. Two letters sometimes appear after the number, as in the 325Ci and 325Xi. The first letter indicates a variant, such as a two-door 325Ci coupe or the all-wheel drive 325Xi. However, not all numbers necessarily reflect the displacement size. For instance, the 335i sedan uses a 3.0L engine and the 550i is equipped with a 4.8L.

Honda

The CR-V is one of only two current models in the Honda stable that has a meaning behind the letters, though Honda is ambiguous about just what CR-V actually stands for. (Photo by Ryan Lee Price)

Overall, Honda lacks a system-wide naming convention. The CR-V is somewhat of an enigma, however: Though Honda sales literature in Europe and Australia makes references to “Compact Recreational Vehicle,” other Honda advertising cite “Civic - Recreational Vehicle,” alluding to the CR-V’s origins in the Civic. The S2000 was an anniversary sports car with a 2000cc engine. The S stands for sport and it was introduced as a 2000 model year.

Infiniti

Low in the alphabet, the G35 is an entry-level Infiniti equipped with a 3.5L engine. (Photo by Ryan Lee Price)

Infiniti employs the straightforward method of basing the prestige of the vehicle on its placement in the alphabet, with the G and E representing entry-level vehicles and the M and Q as full-size luxury sedans. QX is used for its SUV model. The second and third numbers generally relate to the engine size, with the G35 having a 3.5L engine and the QX56 a 5.6L engine. An exception is the QX4 which has a 3.5L engine.

Jaguar

One of the few model names that didn’t fit the mold at Jaguar, the S-Type was discontinued in 2008 to be replaced by a more form-fitting XF. (Photo by Ryan Lee Price)

Jaguar’s early successes, the D-Type (XKSS) and the E-Type (XK-E) followed an alphabetical arrangement that halted when the XJS replaced the E-Type in 1976. The Jaguar model line is based on the letter X, which has no discernable meaning, although the higher in the alphabet of the second letter, the more luxurious the car (X-Type, XF, XJ, XK). Sometimes, the engine displacement data or number of cylinders follows the model designation, for example, the X-Type 2.5 or the XJ8; however, the addition of the letter R, as in XJR or XKR, signifies increased performance, but the letter R has no official meaning.

Lexus

For Lexus, the GS 350 is an entry-level sedan (that’s what the S stands for) with a 3.5L engine. (Photo by Ryan Lee Price)

The second letter in a Lexus model indicates body style, S for sedan, X for SUV and a C for convertible, while the first letter is the relative size and cost of the car; the higher the letter, the more luxurious the car. The exception is the R-class SUV, which is the least expensive. The numbers designate engine size: The IS300 is a lower-cost sedan with a 3.0L engine and the GS350 has 3.5L engine, for example. The exception to the rule is with the RX400h and 600h, hybrids with a 3.3L and 5.5L engines, respectively.

Mazda

The MPV is the only model in Mazda’s line which has an acronym that means something, in this case, Multi-Person Vehicle. (Photo by Ryan Lee Price)

Despite the multiples of three (616, 323, 626), Mazda lacks an overall naming convention, but several of their models do have a method. The B-Series pickups are named in relation to their engine size, such as the B2300, B4000, etc., have 2.4L and 4.0L engines, while its MPV means Multi-Person Vehicle. It was suggested that the RX-7’s name came from the seventh version of the Rotary engine eXperiment. Wankel’s rotary engine was built into the RX-series predecessor, the R100, where R stood for rotary and the 100 was its displacement. The X perhaps comes from Mazda’s project number: In the case of the RX-7, it was X605.

Mercedes

One of the most common Mercedes is the middle-of-the-road E-class sedan. This particular one has a 3.5L engine under the hood. (Photo by Ryan Lee Price)

The single letter in front of Mercedes car names, such as the E in E320, indicate the class. Sedans are C, for the least expensive, while E or S are the most expensive. SUVs use M for the entry level or G for the more exclusive. The three numbers indicate engine size, with some exceptions; a CL600 has a 5.5 liter engine, for example. Other models, in order of luxury are SLK, CLK and SL have long-standing German definitions:

SLK: Sportlich (sport), Leicht (light) and Kurz (short)
CLK: Coupe, Leicht (light) and Kurz (short)
SL: Sportlich (sport), Leicht (light)

Saab

Using the Number 9 has been a long-standing tradition at Saab, and from 2007 on, the 9-3 is Saab’s entry-level model in North America, displacing the Subaru-based Saab 9-2x. (Photo by Ryan Lee Price)

Saab originally stood for Swedish Aircraft, AB (the Swedish equivalent of Inc.), and it used 9 as a moniker for all of its non-military models (e.g. 99, 900, 9000 and 9-3), the 92 being the first civilian car in 1949. The second number in the current line indicates the relative size and price of the vehicle, the 9-3 being less expensive and smaller than the 9-5. If it’s followed by an x, as with the 9-2x, that means it has all-wheel drive. The exception to the “9” naming rule is the Saab 600, which was a rebadged a Lancia Delta in 1980.

Toyota

The Recreational Activity Vehicle, 4-wheel drive is somewhat of a misnomer, as not all RAV4s come equipped with four-wheel drive. (Photo by Ryan Lee Price)

Toyota frequently uses the letter C, perhaps because there is no hard-C sound in Japanese, and it looks and sounds soft and classy. So names like Camry, Corolla, Corona, Celica, Cressida, Century, and Cresta, have been used over the last 50 years. Though there is no alphanumeric naming convention, the Camry comes from the word “Kammuri,” which means crown. Prius is Latin for “before” or “first,” and Yaris is a strange combination of the Greek goddess Charis and the German expression of agreement, ya. RAV4’s name stands for Recreational Activity Vehicle, 4-wheel drive, although not all models have four-wheel drive.

Volvo

Gone is the intricate classification of models for Volvo and what’s left is a simple system based on type of model and series, in this case an 80-series sedan. (Photo by Ryan Lee Price)

Starting with the 140 series in 1968, Volvo used a three-number system for its cars. The first number was the series; the second number indicated the number of cylinders and the third digit the number of doors; so a Volvo 164 had a six-cylinder engine and four doors. There were exceptions: the 760 often was equipped with a turbocharged inline-four engine and the Volvo 360 only had four cylinders.

Today, the company uses a system of letters denoting body style followed by the series number. Although not official, it is fairly accepted that S stands for sedan, C stands for coupe or convertible and V stands for versatile, used strictly for the station wagon line. XC stands for cross country, originally added to the V70 model to become the XC70, sister to the XC90.

The best way to find comprehensive information about most any car on the road is with a subscription to www.ChiltonDIY.com or www.ChiltonPRO.com . Whatever your skill level, there’s a Chilton product tailored for you, your hobby or your thriving business.

Not only is Ryan Lee Price a freelance writer specializing in automotive journalism and a former long-time magazine editor, he is part of the technical editorial team that provides content for most all of the ChiltonPro and ChiltonDIY products. He currently resides in Corona, California, with his wife Kara and their two children.