Timing belts work to time the opening and closing of your engine's exhaust and intake valves in sync with the movement of the crank, pistons and camshafts. Most timing belts have a lifespan of between 60,000-100,000 miles, but check your owner's manual for the recommendation specific to your vehicle's engine. Timing belts should be replaced at the recommended interval because if they go beyond that and then break, it can cause serious damage to your engine and costly engine repairs. Find the right timing belt kit for your engine to keep it running in tip-top shape. Timing belts are available on their own or as part of a kit. If you're changing the timing belt it's recommended to change the waterpump at the same time as they wear at the same rate.