The most important thing to know about timing belt replacement is that it is not an optional piece of car maintenance. Having the timing belt replaced at recommended intervals is critical to the smooth operation of a car. At the very least, a failed belt can put a car out of commission until a new one can be installed, but in some types of engines, it can cause a catastrophic engine failure, which is definitely undesirable.
Timing belts are used to coordinate the crankshaft and the camshaft in a car. These toothed belts coordinate the opening and closing of the valves in the engine to keep it running smoothly. The timing belt design is built to last, with sturdy rubber and reinforcing metal strips, but eventually the belt will wear out, and the engine will not be able to function. Timing belt replacement is ideally performed before the timing belt fails. Some cars use a timing chain or timing gears instead of a timing belt, in which case their maintenance recommendations are a bit different, depending on the car.
As a general rule, timing belt replacement should occur every 60,000 to 100,000 miles (96,561 to 160,934 kilometers). Different manufacturers have their own recommendations, making it advisable to consult the owner's manual for a vehicle. If the owner's manual is not available, a dealer or mechanic should be able to provide information about when the timing belt needs to be replaced.
When the timing belt is replaced, the mechanic also replaces the tensioner, a device which keeps the timing belt tight. Many mechanics also recommend replacing the water pump, because the water pump is linked to the timing belt, and it tends to wear at about the same rate. The procedure does not take very long, although in cars with cramped engine compartments it can be difficult due to the limited room to work. Skilled mechanics can perform timing belt replacement at home.
Some cars have what is known as an interference engine, which means that the valves and the pistons share the same space. When the timing belt is operating correctly, the pistons and valves cannot contact each other. If the timing belt breaks, however, they can collide, causing serious and very expensive damage to the engine. For cars with interference engines, it is especially important to perform timing belt replacement on a regular basis before it fails. In a noninterference design, replacing the timing belt when recommended is still important for the longevity of the car, but a breakage is unlikely to destroy the engine.
