Open bleed valve -arrow- on top of radiator next to expansion tank and keep open until bubble-free liquid flows out.
Close the air release valve on the radiator.
Models 316i/318i: In addition, open the bleed valve -1- on the thermostat housing.
Close the air release valve on the thermostat housing.
Start the engine and push the gas pedal to rev up to 2500 rpm. Remaining air in the system causes the coolant level to drop to approximately the MAX mark on the expansion tank.
During the heating process, add liquid if necessary and then close the lid.
After warming up the engine to operating temperature, leave it to run at a slightly increased idle speed (about 1200 rpm).
Open the bleed valve again and leave it open until only coolant comes out.
Caution Rotating fan and V-belt. Danger of injury!
If necessary, add coolant up to the MAX mark on the expansion tank. Close the radiator cap.
Check the tightness of the cooling system, especially at the hose connections, as well as drain plugs and the water pump.