The drive belt, also known as the serpentine belt, keeps the engine running smoothly. Some vehicles utilize a dual belt system, but most modern automobiles have a single belt. It is a reinforced rubber belt that delivers power to the AC, cooling system, power steering and alternator as the vehicle runs. In most cases these belts will last upwards of 150,000 miles, but at some point they’ll likely need replacement. If you notice either of these signs of drive belt trouble, be sure to visit your local auto shop.