If you are doing the work on the cooling system yourself it is important to make sure the system is properly filled and bled.

This is especially difficult on the 6 cyl cars as you have to get the front end up as high as possible to get the air out of the engine. The shop raises the car as high as possible so that the back bumper is almost on the ground.

For bleeding see the following
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Cooling system bleed procedure – M62 engine (E39 – 97 version)


- with cold car
- top up coolant to proper level.
- leave rad cap loose

This stage bleeds air trapped in the heater system.
- turn on ignition switch to position 2 (no start)
- set temperature selectors on the climate control to max temp.
- manually set the fan speed to low (lower end of speed range)
- start engine (check that climate settings have not changed)
- after 5-10 seconds of running rev the engine 3-4 times to about 2500 RPM - hold
there for about 5 seconds each time.
- shut off engine (should not run for much longer than about 30 seconds - you just want
to shut if off before it starts to generate any heat and expand the coolant).
- inspect the coolant level and top up again if necessary.
- tighten the coolant fill cap.

This stage bleeds air from the engine, rad and fill tank.
- now warm up the engine (drive a bit if you wish)
- with engine running CAREFULLY / SLOWLY open the bleed screw. Hold a rag around the area to prevent any excess splashing. Keep the screwdriver in the slot of the bleed screw so you can close it quickly.
- you should have some air/steam escape - progressing to some bubbles of coolant.
- as soon as it progresses to the stage where you are seeing liquid coolant come out then close the bleed screw. Do not over tighten - it is all plastic threads and you can easily turn too far at which point the screw jumps back a thread and you have to re-tighten. Just make it snug with all coolant stopped.
- when the car is cold again re-check the coolant level and top up again if necessary.

You may have to repeat the bleed procedure 1 or 2 more times over the next week. Can "probably" skip the stage for the cold start bleeding of the heater system.

If the level continues to fall below the correct level then have the system fully pressure tested - explaining to your service manager what you have already done.

It is very important that all leaks be sealed so that the system can operate at full pressure. The engine computer is programmed to keep the coolant temp at about 108C at "most" times (there are exceptions) and the only way it can maintain that temp is if the pressure can be maintained - system fully sealed.

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