A timing belt, or cambelt as it is also known, provides the correct synchronisation of the engine's internal rotating parts. It is hidden behind a cover to protect agains objects falling into it so is not normally visible without stripping down the front end of the engine. The timing belt is guided around pulley wheels and tensioners and links the crankshaft to the camshaft(s) ensuring that the inlet and exhaust valves work in correct synchronisation with the crakshaft and pistons. The belt is a toothed belt so frictional slippages cannot happen, it is also fabricated with internal cords to prevent any stretching. The quality of the belt and associated pulleys and tensioners and in some cases, the water pump drive is of the highest importance which is why it is always preferable to fit the original manufacturer's parts when replacing. In some instances, where the water pump is associated with the timing belt it is good policy to fit a new pump as 90% of the required labour to do this has already been done. A failure of the water pump seals or bearings, at a later date, will mean the labour charge for replacement being a repeat of the timing belt labour. Some later engines have a secondary belt, commonly known as a balancer belt which, within the engine, to provide the variable valve timing used in modern fuel economic and performance engines. If the manufacturer recommends replacement, then this will be included.
The belt revolves at 100s of revolutions per minute, withstanding extreme mechanical and thermal stresses, so replacing the belt and tensioners at the scheduled intervals is essential maintenance. Failure to follow the manufacturer's recommendations can have costly implications. It is fairly common for some manufacturer's to publish reduced intervals, less than those found in the car manual so it is always a good policy to check for the latest information. Sterling Garage can assist with this on most makes and models.
If your car's timing belt breaks or slips then the correct synchronisation of the engine's crankshaft and camshaft(s) is lost. Consequent serious damage to the engine's internal components can take place as the engine's valves and pistons collide. Repairing the engine is expensive and in extreme cases fitting a new engine is the most cost effective solution.