A drive belt is used to drive accessories installed on your car engine, such as an alternator,water pump, power steering pump, air conditioner compressor, etc. Sometimes a drive belt could also be called a “serpentine belt” or “accessories belt”. Some cars have a single drive belt running all the accessories, others may have two or more drive belts.
Drive belt tensioner
A belt tensioner keeps the drive belt under proper tension. In some older cars, a belt tensioner had to be manually tightened from time to time. If not tightened in time, the belt would get loose and start slipping, making a loud whistling or squeaking noise. Commonly you would hear this noise when the car is just started cold in the morning or when turning the steering wheel left or right to the limit.
Most of the newer cars have a drive belt with a self-adjusting tensioner that maintains proper belt tension automatically.
Drive belt problems
A drive belt is made from very flexible and durable material, but it still wears over time. Improper tension, excessive heat and the engine oil leaking onto the belt cause the belt to wear faster.
What happens if the drive belt breaks
A badly worn drive belt can break without warning signs and all the accessories driven by the belt will stop working leaving you waiting for a tow truck. This happened to me once in the early days and I spent few hours on the side of the road waiting for towing. In many cars a serpentine belt drives a water pump and a power steering pump. If the drive belt breaks, the engine will overheat as the water pump will stop moving the hot coolant into the radiator to cool it down. A car will also lose a steering assist and the steering will become very hard. For this reason it’s important not to overlook a drive belt during a regular maintenance and replace it at recommended intervals.
A drive belt also needs to be replaced if it shows any damage, such as cracks, tears, cuts, etc. (lower photo). It’s also a good idea to replace a drive belt before a long road trip if it’s been a while since it was changed the last time.