Cooling System: Service and Repair

Cooling System, Bleeding (Radiator with integral expansion tank)


NOTE: On radiators with a separate expansion tank, a bleed screw is not provided The cooling system with separate expansion tank is self bleeding via the vent hose on the expansion tank

Air may become trapped in the system during filling. Trapped air can prevent proper coolant circulation. Whenever the coolant is drained and filled, the system should be bled of trapped air.
1. With engine cold, add coolant to expansion tank until level reaches COLD (KALT) mark on tank.
2. Loosen bleed screw on radiator expansion tank. See Fig. 7.




Fig. 7. Cooling system bleed screw on radiator (arrow). Note cold level mark on expansion tank.
3. M3 models: Loosen bleed screw on thermostat housing.
4. Set temperature controls in passenger compartment to full warm and turn ignition on position (do not start engine).
5. Slowly add coolant until it spills from bleed screws. When coolant spilling from bleed screws is free of air bubbles, tighten screws.
6. Run engine until it reaches operating temperature. After engine has cooled, recheck coolant level and top up as necessary.

CAUTION: Always use genuine BMW coolant or its equivalent to avoid the formation of harmful, clogging deposits in the cooling system. Use of other antifreeze solutions may be harmful to the cooling system.

Tightening Torque
- Radiator bleed screw to thermostat housing 8 Nm (71 in-lb)