Fan and viscous coupling (BMW X5 E53)

The fan has nine blades, is mounted on the coolant pump shaft and is designed to create an air flow through the radiator. The fan impeller has a diameter of 420 mm and is connected to the coolant pump drive via a viscous coupling.

The viscous coupling is manufactured by Holset or "Fichtel und Sachs". The switching on and off of the fan viscous clutch depends on the engine temperature and the rotation speed of its crankshaft.

Fan switch-on temperature is 88–92°C, switch-off temperature is 60–65°C.

Axial clearance of the viscous coupling rotor, no more than 0.4 mm.

Radial clearance of the viscous coupling rotor, no more than 0.65 mm.