Coolant Reservoir: Service and Repair

17 11 100 Removing and installing/replacing coolant expansion tank (M54 / M57)

Warning:
Danger of scalding!
Only perform this work after engine has cooled down.

Note: Follow instructions for working on cooling system.

Remove front underbody protection.

Recycling
Catch and dispose of escaping coolant.
Observe country-specific waste-disposal regulations.





Installation:
Slowly top up coolant expansion tank with coolant until marking (2) on float needle has reached height of top edge on expansion tank (maximum fill level).
Use only recommended coolant.

Note: :Tank marking indicates coolant level at approximately 20°C.

Vent cooling system and check for leaks.





Open cap (1) on coolant expansion tank.

Manual transmissions only:
Drain coolant from coolant expansion tank via drain plug (2).
2AZ Bleeder screw (8 mm wrench size) on thermostat housing All, without E46 8 Nm





Lever out locking clamp (1).
Detach hose (2) from connection piece.





Unfasten plug connection (1) and disconnect.
Pull out lock (2).





When replacing expansion tank:
Unlock coolant level sensor (1) by turning and pull out of coolant expansion tank.





Pull lock (1) upwards and detach coolant hose (2) from coolant expansion tank.





Pull lock (1/2) upwards and detach coolant hose.





Pull coolant expansion tank first upwards and then towards rear out of retaining plate.
Withdraw coolant expansion tank from lower connection piece.





Installation:
Check sealing rings, replace if necessary. Do not under any circumstances coat sealing rings with antiseize agent.
Retaining lug must engage in opening in retaining plate.