Table of contents: 5-cylinder engines only ↓ Malfunctions ↓
5-cylinder engines only
The hydraulic fan creates a continuous air flow through the radiator grille when the flow from the main electric fan is insufficient. To increase the service life of the additional fan and save energy, Audi equipped the fan, which is powered by a V-ribbed belt, with a so-called liquid clutch. At an ambient temperature of approximately 82°C, the hydraulic fan starts to operate. This is done by means of a valve (bimetallic plate), through which flows (depending on the temperature) oil into the working cavity of the liquid clutch. The oil creates a clutch between the V-belt pulley and the fan, which increases the air flow through the radiator grille and reduces the ambient temperature. When the temperature reaches approximately 60°C, the oil flows from the clutch back into the reservoir. After that, the fan rotates by inertia at a lower speed, without wasting energy and performing the cooling function.
Malfunctions
The fluid clutch should be replaced if:
When the engine is running steadily, the hydraulic fan is difficult to turn.
The hydraulic fan has developed a large axial or radial gap (a slight gap of up to 15 mm in the fan wheel diameter is acceptable).
Oil is leaking from the clutch fluid chamber.
Unscrew the radiator at the top (left and right) from the front of the engine compartment.
Disconnect the air ducts from the air filter.
To secure, insert the open-end wrench into the holes on the surface of the fan pulley.
Using a 32 mm wrench, unscrew the fan from the pulley.
Place the fan into the fan housing in the radiator (that's the "ring" around the fan).
Unscrew the fan tsarga.
Carefully pull the column upwards together with the fan.
If necessary, unscrew the fan clutch.
When assembling, tighten the screw to a torque of 70 Nm. If it is too loose, the fan may become loose and damage the radiator.
The tightening torque of the fan to the clutch is 10 Nm.