Timing belt (camshaft)

This synchronisation ensures that the engine's valves open and close at the correct times in relation to the position of the pistons.

[2] The most common devices to transfer the drive are toothed rubber belts, metal timing chains or a set of gears.

Timing belts are typically located in front of the engine and are often behind a cover for protection against dust and debris.

Older belts have trapezoid shaped teeth leading to high rates of tooth wear.

[citation needed] Newer manufacturing techniques allow for curved teeth that are quieter and last longer.

Manufacturer-specification timing belts may stretch at high rpm,[citation needed] retarding the cam and therefore the ignition.

Carmakers began to adopt timing belts in the 1970s and compared to timing chains are less expensive, smaller, lighter, quieter, isolate harmonics of the crankshaft from the valve train, require less power than chains and can potentially function without lubrication.

[citation needed] Timing gears are used in various overhead valve engines, due to the close proximity of the camshaft to the crankshaft.

Many modern cars use interference engines, which can suffer catastrophic damage in the event of timing system failure,[26] since the loss of synchronization between the crankshaft and the camshaft will cause the valves to collide with the pistons.

Warning signs that a timing chain needs to be replaced include:[27] Aside from the belt/chain itself, also common is a failure of the tensioner, and/or the various gear and idler bearings, causing the belt/chain to derail.