Specialized Automotive Tools

The standard hand tools we just described are often used in automotive repair. However, many repair situations involve procedures that can’t be performed with standard tools. For example, most automobiles contain oil filters that filter dirt out of the engine oil. An oil filter is shaped like a small can, and is threaded into a fitting on the engine (Figure 1A).

Figure 1

Since oil filters are used to trap dirt, they must be periodically unthreaded from the engine and replaced. However, note that the oil filter has smooth sides, and there’s no obvious way to attach a wrench to it. How is the filter unthreaded from the engine? The answer is that a special wrench designed just for this purpose must be used.

Figure 1B shows a strap-type oil filter wrench. This wrench has a thin metal strap that’s placed around the filter and tightened so that the filter can be removed. Figure 1C shows an end cap oil filter wrench. This type of wrench fits over the fluted end of the oil filter and is turned with a square drive handle. The advantage of a strap-type oil filter wrench is that it can be tightened to fit around any size of oil filter. In contrast, the end cap types come in different sizes, and the correct size must be used with each different filter. (Related: engine oil pressure

The oil filter wrench is just one example of a specialized auto repair tool. A specialized tool is one that’s designed to be used for only one limited purpose. Many special tools are required for auto repair, especially to rebuild components like the engine or transmission. Special tools are also used to work on brake and suspension systems. As you learn more about the auto repair field, you’ll find that a special tool is made for almost every purpose you can think of. You should also be aware that some special tools are designed to be used on only one make or model of vehicle, while others can be used on a variety of vehicles.

Pullers

Pullers are used to help remove gears, pulleys, and various fittings from shafts safely and with little effort. A puller can easily separate machined parts that are tightly pressed together without damaging the parts. The external jaws of the puller apply the pulling force while the center “forcing” screw presses against the stationary part. Standard pullers may be either the two-arm/two-jaw or three-arm/three-jaw type, and they range widely in length. For safety reasons and to protect precision parts, you should use pullers whenever possible to separate parts (rather than a hammer and pry bar).

Cylinder Hones

A cylinder hone is used to recondition the surface of a cylinder wall during an engine rebuild. The hone has several abrasive polishing stones attached to it. The cylinder hone is attached to a power drill and is then inserted into an engine cylinder. When the drill is turned on, the spinning hone will polish and smooth the inside surface of the cylinder.

Piston Ring Compressors

Remember that a piston has several piston rings installed on it. The piston rings press outward from the surface of the piston to press against the cylinder walls. However, when you’re assembling an engine and you need to install a piston in a cylinder, the piston rings get in the way. Because the rings stick out from the surface of the piston, they prevent the piston from sliding smoothly into the cylinder.

For this reason, a piston can’t be inserted into an engine cylinder without using a special tool called a piston ring compressor. A ring compressor has a thin metal band that’s placed around the outside of the piston and then tightened. When the tool is tightened, the piston rings are pressed into their grooves, and the surface of the piston is smoothed. The piston can then be slid into the cylinder. Once the piston is inside the cylinder, the compressor tool is released. The piston rings then spring back into their original positions and press out against the cylinder walls.

Valve Spring Compressors

In an engine, the intake and exhaust valves are held in the closed position by springs. During an engine rebuild, these valves will need to be removed from the engine for servicing. In order to remove the valves, their springs must first be compressed and held tightly. A valve spring compressor is a clamp-like tool that’s used to compress and hold a spring

Universal Sensor Sockets

A universal sensor socket is a special socket that’s used to remove sensors from an electronic engine control system. The sensor socket is designed to protect the sensors from damage as they’re removed. Note that the socket has a slot in its side. Certain sensors (such as oxygen sensors) have wires attached to them, so the slot is provided to hold such a wire as a sensor is being removed.

Brake Spring Pliers

Many automotive brake systems contain springs that release the brakes after they’ve been applied. Since these springs are always under tension, they have to be stretched slightly in order to remove or install them. There are several special tools designed for removing brake springs. One of the most common is the brake spring pliers.