Why should ball joints and tie rod ends be changed in pairs? It is not absolutely necessary, but many professional installers insist on replacing both even if only one is bad. This is because both have more or less the same mileage and sooner or later the other one is going to fail too. In [...]

Why Replace Rack-and-Pinion Steering Rather Than Rebuild It? Overhauling a power rack is not a job for the novice. Special tools are required to remove and install internal seals. The tools are expensive and may not be cost justified for a shop that only does an occasional rack. For a do-it-yourselfer, the tools could end [...]

Why Do Some Engines use RTV Sealer Instead of Gaskets? For a period in the 1980s, domestic auto makers thought they could lower production costs and improve sealing by using RTV (Room Temperature Vulcanizing) silicone instead of conventional cut gaskets to seal valve covers, oil pans, timing covers, transmission pans, and other parts. In theory, [...]

Why Preventive Maintenance Manufacturers know that a properly maintained car will be more dependable, safer, last longer, and increase your satisfaction with their product. Car makers and owners also have a responsibility to make sure emission controls receive regular service and are functioning properly. Regular maintenance helps accomplish these goals by keeping your engine running [...]

Why Are There No Returns On Electrical and Electronic Parts? Too many people have tried to take advantage of the system. Instead of using proper diagnostic procedures, some people (mostly do-it-yourselfers, but also some so-called professionals) resort to trial-and-error parts swapping when they don’t know how else to fix an electrical problem. When parts they [...]

Why Are There Many Different Types of Spark Plugs? Spark plugs need 5,000 to 40,000 volts from the ignition coil before a spark will jump across its electrode gap. It takes a lot of volts to push the spark across the gap because air doesn’t conduct electricity unless it is ionized first. The spark jumps [...]

All sensors are important. The computer is the brains of a computerized engine control system and sensors are its link to what’s happening under the hood. Some sensors have more influence on engine performance than others. These include the coolant temperature sensor, oxygen sensor, throttle position sensor, and manifold absolute pressure sensor. The coolant sensor [...]

New lifters should always be installed. Reusing worn lifters on a new cam is asking for trouble. With flat tappet cams, lobes are ground with a slight taper so they will spin the lifters as they push them open. The lifters are also slightly convex on the bottom to reduce the point of contact and [...]

Use the type of motor oil specified in your customer’s owners manual. Most manuals say it’s okay to use a variety of viscosity grades depending on temperature conditions. Generally speaking, the following holds true: 10W-30 is best for all engines for year-round driving. 10W-40 is more popular in the aftermarket, but 10W-30 is actually a [...]

Everything needed to restore a cylinder head to like-new condition, including basics such as: Cleaning cylinder head and valve train components Inspecting head for cracks, leaks, warpage, or other damage Inspecting valves, seats, springs, guides, and other valve train components for wear and damage (and replacing parts that cannot be reused) Grinding or cutting valves [...]

Electronic ignition, computerized engine controls, and electronic fuel injection have eliminated many adjustments that were once part of a "traditional" tune-up. Most would agree that a tune-up today is a preventive maintenance service and engine performance check. Call it what you will, a complete tune-up should combine elements of preventive maintenance, adjustment and performance analysis. [...]

What Kind of Replacement Pistons Are Best Ordinary cast pistons are usually adequate for most passenger car applications. When it comes to modified or high output engines, racing engines, marine engines, and severe-duty applications, ordinary cast pistons may not be adequate in terms of strength, durability and longevity. Higher operating speeds, horsepower output, torque loads, [...]

Replacing coolant on a regular basis will prolong the life of the radiator and other cooling system components. Most new car maintenance schedules call for coolant changes every three years or 50,000 miles. Many professional mechanics consider that too long and recommend every two years or 24,000 miles. There are some who argue that annual [...]