Thermostat: Service and Repair

Thermostat (B235R, B205L/R)

To remove





1. Open the expansion tank's pressure cap to release system pressure.
2. Raise the car.
3. Drain the coolant by connecting a hose and opening the drain plug. Collect the coolant in a suitable receptacle.
4. Check that the cooling system's drain plug is closed and lower the car to the floor.





5. Remove the cover over the throttle body.
6. Undo the hose clip on the upper radiator hose by the thermostat housing and bend the hose aside.





7. Remove the mounting for the coolant pipe by the thermostat housing.
8. Undo the upper and lower thermostat housing screws.





9. Remove the thermostat housing and thermostat.

To fit





1. Check and clean the sealing surfaces. Lubricate the rubber seal with a little nonacidic vaseline, part no. 30 06 665, or the equivalent.
2. When fitting the thermostat, make sure that the bleed hole faces up ("TOP" marked on thermostat).





3. Fit the thermostat housing.
Tightening torque: 22 Nm (16.2 ft. lbs.)
4. Fit the mounting for the coolant pipe.





5. Place the upper radiator hose in position and fit the hose clip. Attach the radiator hose.
6. Fit the throttle body's cover.
7. Fill up with coolant. For the correct mixture, refer to Coolant, Specifications.
Close the filler cap.
8. Bleed the system as follows:

Note: A/C and ACC must be OFF.

Fill the cooling system up to the MAX level, fit the pressure cap, start the engine and warm it up at varying rpm until the radiator fan starts. Open carefully and top up to the MAX level.