Petrol engines: Open bleed valve 1 on thermostat housing. On the 518i, the valve is located directly below the ignition distributor.
Models 518i, 520i, 525i only: In addition, open the bleed valve -arrow- at the top of the radiator next to the expansion tank.
Diesel engine 524td: Open bleed valve -arrow- on thermostat housing.
Pour coolant through the opening in the expansion tank until the tank is full and coolant flows out through the air release valves. The illustration shows the expansion tank on 530i, 535i and diesel engines.
On the 518i, 525i and 525i models, the expansion tank is located directly below the radiator.
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.
Check the tightness of the cooling system, especially at the hose connections.