A timing belt is the ribbed belt that is placed in a specific configuration along one side of your engine to keep the crank and camshafts timed properly basically it keeps the top half of the engine in sync with the bottom. If you have an older car from the 90s and below odds are you have a timing belt. Some new car manufacturers, such as Audi, still use timing belts in their engine designs but for longevity many manufacturers have switched to metal timing chains. It’s best to replace your timing belt every 60,000 miles or every 5 years.
A four stroke engine requires that the valves open and close once every other revolution of the crankshaft. The timing belt does this. In some engine designs the timing belt may also be used to drive other engine components such as the water pump and oil pump. Chains and gears may be more durable, rubber composite belts are quieter in their operation are less expensive, more efficient, by dint of being lighter, when compared with a gear or chain system.
An Indicator that the timing chain may need to be replaced includes a rattling noise from the front of the engine. The usual failure modes of timing belts are either stripped teeth or delamination and unraveling of the fiber cores.