Vehicles manufactured today use a serpentine belt. The name is because the way belt snakes around the pulleys in the engine compartment. Serpentine belts are multi grooved belts. Most are kept automatically adjusted with a spring style tensioning device, with a pulley running against the belt. Serpentine belts have gone through some changes; these new belts can last 50,000 to 80,000 miles. Because of the great improvements in materials, these belts no longer crack but they do wear. When these belts wear they slip, sometimes making noise. But they can also wear on the pulleys, which can be an expensive repair, if ignored. The belt drives items such as your alternator which main job is to charge and maintain your battery and electrical demand. The belt drives your ac compressor to cool the passenger compartment. The belt also drives your power steering pump, which helps you steer your vehicle at lower speeds. The belt may also drive your water pump which circulates the coolant/antifreeze in your engine to keep your engine running cool. Some vehicles may have a vacuum pump to help with brake assist to help stop your vehicle.
Your belt can easily be overlooked as looking fine, but will lead you to a failure. So it is imperative to have it inspected by a technician and replaced at regular intervals.
Appearance: Belts made from a material known as chloroprene show traditional signs of wear (cracks, chunk-outs, rib separation, etc). But the new belts of today called EPDM (ethylene propylene diene monomer) belts don’t necessarily exhibit these symptoms even though they might be at or near failure as much of the rubber material has worn away.
Cause: EPDM is stronger, is suitable for a wider range of extreme temperatures, and it is more durable. EPDM belts gradually lose rubber material − similar to the way tires wear out.
Solution: Visual inspection is still a good idea, but the traditional signs of wear need to be looked at more closely and inspected with a Groove Pic Gauge by an automotive technician to detect an EPDM belt that is near failure.