Critical to the operation of your vehicle, the timing belt synchs the operations of the camshaft and the crankshaft so that the valves operate efficiently and safely. Older cars may have a timing chain, similar to a chain on a motorcycle, with a life cycle of around 60,000 miles. Newer models use timing belts made of polyurethane and Kevlar for long life and durability. They can go as long as 100,000 miles although it’s always a good idea to change it before then. Belt failure can cause extensive damage to the valves, pistons and other internal parts of the engine. The cost of changing the timing belt is a bargain when you consider the cost to replace the entire engine. Start thinking about changing the timing belt once you cross the 90,000-mile threshold. Check your owner’s manual for details.