Timing belts

The timing belt is a nylon-reinforced rubber serpentine belt with square teeth on the inside surface. Its function is to transfer the rotation of the engine crankshaft to the camshaft -  the component that moves the piston valves up and down.

The timing belt governs the precise timing of the opening and closing of the cylinder's valves. By controlling the ignition of the fuel/air mixture, it secondarily controls the motion of the pistons. In the case of a broken belt, the pistons will complete their cycle even with inert valves. If the belt that regulates the valve motion breaks, the piston will continue to travel but the valves do not. The piston can collide with the valve mechanism causing damage to any number of costly components: valves, valve stems, pistons, cylinder head, cylinder walls.