17 00 039 Venting cooling system and checking for leaks (M62)

WARNING: Danger of scalding!
Only perform these tasks on an engine that has cooled down.

Check cooling system for leaks. Top up coolant.

To ensure the cooling system is properly vented, it is absolutely essential to follow the steps below:

Open cap on coolant expansion tank.
Turn on ignition
Set heating controller to maximum temperature
Set fan to low setting. This opens the heating valves and starts the auxiliary water pump.
Carry out filling procedure slowly
Close vent plug when bubble-free coolant emerges
Fill expansion tank until full.
Close coolant expansion tank
Allow engine to warm up until thermostat opens

Fig 1: Opening Cap On Coolant Expansion Tank
Courtesy of BMW OF NORTH AMERICA, INC.

Allow engine to cool down before checking coolant level. Coolant temperature must not exceed 30°C. If ambient temperature exceeds 30°C, allow engine to cool down at least to ambient temperature.

Check coolant level; if necessary, top up coolant until liquid level reaches marking on coolant expansion tank.

NOTE: The tank mark indicates the fluid level at approx. 20°C.
Use only BMW coolant.

Fig 2: Identifying Tank Mark

Courtesy of BMW OF NORTH AMERICA, INC.