Bleeding Cooling System

Bleeding cooling system

To bleed cooling system

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. Add coolant to expansion tank until level reaches COLD mark on tank.






Cooling system bleed screw on 525i models (arrow). Also note cold level mark on expansion tank

2. On models with radiator-mounted expansion tank, loosen bleed screw on radiator expansion tank. Add coolant until it spills from bleed screw. Tighten screw.






Cooling system bleed screw (arrow) on 535i model.

3. On models with separate expansion tank, loosen bleed screw on thermostat housing. Add coolant to expansion tank until it spills from screw. Tighten screw.
4. Set temperature controls in passenger compartment to full warm and start engine.
5. With engine idling at normal operating temperature, loosen bleed screw. Tighten screw when coolant spillmg from bleed is free from air bubbles.
6. After engine has cooled, recheck coolant level and add coolant 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 anti-freeze solutions may be harmful to the cooling system.