This V-belt drives the engine cooling fan from the crankshaft pulley. It is a toothed (synchronous) belt, which prevents slip that a plain V-belt would experience under the cyclic loads of fan engagement. The belt sits in the fan-drive pulley system; a worn or glazed belt will cause the fan to spin below its design speed, reducing airflow through the radiator and leading to elevated coolant temperatures. As an original-manufacturer component, the belt matches the pulley groove profile and tooth pitch of the original assembly, so no adjustment of the tensioner position is needed to maintain correct engagement. On replacement, inspect the tensioner pulley bearing and replace the belt only after the engine has fully cooled.