Prepare your vehicle to be Ready for the Road Ahead™, with the Dayco 89479™ Heavy Duty Automatic Belt Tensioner that provides optimized drive belt tension. To deliver ample amounts of power to engine accessories such as AC compressors, water pumps, steering pumps, and alternators, this replacement tensioner works to create the correct amount of tension on drive belts. Symptoms of a tensioner that needs to be checked or removed include engine squeals, chirps, rattling sounds, or visible frays on a belt. FleetPride is your First Click in Heavy Duty®.