Download If necessary, remove air duct. Note: S54 (M cars) Remove engine underguard and release fan cowl. Caution: Left-hand threads. Using special tool 11 5 030, grip pulley and unfasten cap nut from water pump using special tool 11 5 040. If necessary, unfasten fan cowl. Take the fan wheel with fan coupling off the water pump and remove. Installation: Tighten down fan impeller using special tool 11 5 040. Tightening torque, refer to Specifications, Mechanical. Note: When using special tool 11 5 040, 30 Nm on the torque wrench scale are equivalent to a tightening torque of 40 Nm. Unfasten screws and detach fan from fan coupling.