overheating problem

[E34maystar]

I have a continuos overheating prob wihh my E34 535i .. have fitted new 750i rad to keep it cool, brand new water pump, but still no cant run longer for more than 15 minutes before chucking all the water out through the expansion tank at an extreme temperature.. any idea's .. or have i blown the head Again.

[Jay 535i]

I had a similar problem last year. I spent a lot of money on diagnostics and a lot of time trying to figure it out. In the end, it was a blocked pisser hose, remedied by pushing a paperclip into the little hole in the expansion tank and wiggling it around. Problem solved. The obstruction was around #9 in this diagram:

http://www.bimmer.info/forum/attachment.php?attachmentid=1810&stc=1&d=113062721 5

It may not help you, but I'd start there, since it's a very easy and very free thing to do.

Here's the thread I posted that eventually lead to a solution:

http://www.bimmer.info/forum/showthread.php?t=12836

[ILoveMPower]

E34's are pretty sensitive valvetrains when it comes to heat, I wouldn't be surprised if you seriously did some damage by now if you're continuing to run it although while overheating.

[califblue]

had the same problem...replace the cap..once it is overheated it is ruined
how is your fan clutch? it should sound like a helecopter at low speeds

[632 Regal]

did you bleed it correctly? If you didnt thats most likely the problem, those systems MUST be bled!

[123456]

If overfow line is clogged will it prevent the auxillery fan from activating>

replaced thermo switch already.

ran the fan by jumping the wires and it runs.


What next to bring down the temp gauge?

thanks