Engine idler pulley 8M6500024 is for use on 4.3L, 5.0L, 5.7L, 6.2L & 8.1L MerCruiser sterndrive and inboard engines. This thermal resin pulley is 3 in. in diameter, is flat with no grooves. The pulley is made of long-lasting thermal resin. The bearing is molded into the pulley. When replacing the idler pulley, check the pulley support bushing and serpentine belt for damage or wear. Replace as necessary to help keep your engine running at its peak performance.