Draining and Adding Coolant

Note: After filling the cooling system, vent the system and check for leaks.

Drain coolant!

Only perform this work after engine has cooled down.

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

Unfasten cap on expansion tank.

Unfasten cap on expansion tank.
Release vent screw.

If necessary, remove front underbody protection.
Unscrew drain plug at bottom of radiator.

Installation:

Replace seal.
Tightening Torque, refer to Cooling System, Specifications.
Drain, catch and dispose of coolant.

If necessary, remove front underbody protection.
Cars with automatic transmissions:
Turn hose plug (1) to left and detach towards bottom.
Cars with manual transmission:
Remove drain plug at bottom of radiator.
Drain, catch and dispose of coolant.

Unfasten drain plug on engine block.

Remove drain plugs on left and right of engine block.

Installation:
Replace seal.
Tightening Torque, refer to Cooling System, Specifications.
Drain, catch and dispose of coolant.

Top up coolant!
Slacken vent plug (2) on expansion tank.

On vehicles with M52 engines, also unfasten additional vent screw.

On cars with latent heat accumulators, do not turn on ignition when filling cooling system.
Follow venting procedure specified.

Note: Before filling:
- Switch on ignition.
- Set heater control to maximum temperature.
- Set blower to low setting. This opens the heating valves and sets the auxiliary water pump in operation.

Perform filling operation slowly.
Fill up expansion tank fully and wait until bubble-free coolant emerges from vent point. Close vent plugs.

Note: Use only recommended coolant.