In most engines, there are anywhere from one to four auto belts that run some of the most basic parts of your engine. The belts are easy to forget about — they don’t require attention as often as oil changes — but they are incredibly important.
Most auto belts in vehicles are made from rubber or a combination of rubber and plastic. This combination of materials has a tendency to wear out, crack and decay. The tension the belts are under combined with the hot-and-cold conditions they usually run under means that they will stretch and break. Auto belts usually run the cooling system, alternator, and accessories in a vehicle. In some cars, there are three or four separate belts that run each part. In most modern vehicles, there is one long serpentine belt that runs everything.