BMW Repair: Overheating problem, cylinder head gasket, bmw e32

Question

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Followup To

Question -
My BMW E32 - 735i from July 1990 with a/c and automatic gear - is overheating while idling and while I am driving slowly in e.g. heavy traffic. The temperature goes (fast) down to normal again if it is given high r.p.m. in neutral gear. At normal speed around 3000 r.p.m. the temperature gauge is "only a little bit to the right of vertical". The problem is still not solved even after having got the following new items: thermostat, fan clutch, new radiator, new water pump, cylinder-head gasket and a new cylinder head.

What else can be looked at to solve the problem.

Cheers, Hans P. Joensen


Answer -
You have replaced just about everything there is to repair a problem like this,did you physically put an outside temp gauge to make sure your factory gauge is reading correctly?The vehicle is 16 years old.Ceheck all your grounds especially those under the dash in the group grounding point.They are the brown wires bunched together

FOLLOWUP
Yes, the factory gauge is reading correctly. It is really overheting - it "boils". I have also been looking at the bypass hose, and checked that the pipe that runs from the radiator to the expansion tank is open. Looking at the water flow trough the hole in the expansion tank that follows the pipe that runs from the radiator show an rather irregular flow when idling - like it spit the water into the expansion thank. So it seems like a cirkulation problem.

Cheers, Hans P. Joensen


Answer
Are you sure that you have bled all the air out of the system?The bolt/nut is located on the thermostat housing.By constantly changing one part after another you have introduced alot of air possibilities.Have you done all the engine work or did a garage do it?There are alot of parts and there shouldn't be any problems.Does your electric fan come on?Let me know