Fan Clutches

A fan clutch controls engine-driven fan speed. When the engine is cool, the clutch slips to save power and reduce noise; as radiator air temperature rises, a bimetallic spring or coil engages the clutch using silicone fluid. Failed clutches are a frequent cause of overheating on pickups and trucks working at low speed in hot weather.

Types include thermal viscous clutches (coil or flat bimetal), non-thermal viscous clutches and electronically controlled clutches on some newer engines. Specify by OEM number, pump or bracket bolt pattern, fan mounting pattern, rotation direction and overall depth. Clutches contain silicone fluid and should be stored and shipped upright. Pair with cooling fans and water pumps.