What Is a Timing Belt Pulley? Definition, Meaning and Concept

A timing belt pulley is part of the timing belt system for a car. A timing belt is a way of controlling the opening and closing of engine valves by connecting the crankshaft to the vehicle's camshaft. Generally, the timing belt does this by having teeth that lock onto the teeth of the two gears for the crankshaft and camshaft.

A timing belt is one of several belts used in conventional cars and other vehicles. A serpentine belt is a belt that drives various other engine accessories off of the crankshaft. The serpentine belt can power an alternator, power steering pump, and air conditioning compressor. On some vehicles, these jobs are split between multiple belts, where a vehicle typically has only one timing belt pulley.

Each belt on a vehicle may have additional pulleys to route it around the engine compartment. An idler pulley is a pulley that provides movement to the belt but does not drive an accessory or engine component. A timing belt idler pulley can help provide additional track routing for the belt. The idler timing belt pulley can also be called an idler pulley if it helps provide tension on the belt. An idler pulley is one that the vehicle owner or mechanic can adjust to change the amount of tension on the belt when needed.

A timing belt is a crucial part of engine operation. Damage or malfunction of the timing belt will be a serious impediment to driving the vehicle. Those who experience problems with a vehicle's timing belt should consult a professional mechanic who can properly calibrate and repair the timing belt for regular vehicle operation.

Although most drivers prefer to let experienced mechanics work on any idler or idler belt pulley when belts are having problems, others can learn how to do basic work on their vehicles, including how to change the tension of a belt by moving the pulley. Most tensioner pulley setups will include multiple bolts that hold the pulley in place. The person working on the vehicle can loosen the bolts, then adjust the tension by moving the pulley along a threaded bolt, or by prying it toward or away from the engine block.

Individual vehicle owners often look at how to replace a serpentine belt or timing belt pulley for their specific car, truck, or other vehicle. Each car or vehicle model has its own specific configuration for timing and serpentine belts and the pulleys involved. Many vehicles have belt routing diagrams, either on stickers under the hood or in the owner's manual.