The serpentine belt (also called a drive belt) powers several critical systems in your vehicle, most commonly the power steering, air conditioning, alternator, and water pump (for the cooling system). This belt is the link between your engine and these important accessories, transferring energy from the crankshaft to the systems that enable you to start, steer, and cool your vehicle. Certain vehicles use two drive belts to power these components. Preventive maintenance on the serpentine belt includes occasional replacement of the belt and (on some vehicles) periodic adjustments to the belt’s tension. Neglecting the serpentine belt long enough will compromise every system the belt controls -- and ultimately disable your vehicle. The good news: a serpentine belt can last up to 100,000 miles.