Here is the bleeding write-up by Jim cash:

Hot engine
- take car for a run to get up to operating temp
- using caution - slowly open the bleed valve (steam and bubbles may come out)
- close as soon as you see liquid coolant without excessive bubbles.
- do not overtighten this as they are plastic threads. Just snug till it seals fully.
- after engine cools check the coolant level again and top up if necessary.

Check coolant level every few days for a few weeks and top up again if required
- repeat the Hot engine bleed process again.

The following are my questions/comments:

1. When open the bleed valve I assume the radiator cap is closed and engine still running(?)

2. As in my case steam and bubbles came out intermittently with coolant stream: there was no liquid coolant ONLY. Why?

3. After engine cools... --> how cold? overnight? one third of the temp meter? In my case after engine cools (about one or two hours after engine turned off) the upper and lower radiator hose shrinks which will be back to normal only by opening the bleed valve. What and where things have gone wrong? Never have this before with my late 520i/E34/M20/1990.

4. After doing so, coolant level keeps dropping despite several top up.

5. Check coolant level every few days for a few weeks... --> Normally how long will it take to completely empty air from the system?

6. Specific question: under normal driving i.e. shift lever at "D" position cooling system appears to work fine and is able to maintain normal temp for several days until it eventually needs top up (average 2 weeks interval) however when shifted to "S" or "M" mode coolant level would be drastically drop (or drained) the following day. I realized this when driving the car and saw the temp needle rise up. This is my long outstanding issue until now. Please help.


Enrico Tobing