This belt tensioner maintains proper tension on the fan drive belt, preventing slip and ensuring consistent airflow across the cooling system. It mounts to the engine front cover and uses a spring-loaded arm to apply constant pressure to the belt span between the crankshaft pulley and the fan hub. A worn tensioner allows belt flutter, which reduces fan speed and can cause overheating under sustained load. The manufacturer machines the pivot bore and spring pocket to the same tolerances as the original assembly, so the arm aligns correctly with the belt path without shimming. On replacement, inspect the belt for glazing and replace it if the tensioner is replaced.