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angusbn
06-22-2008, 02:01 PM
1989 535i - >400,000km - have owned this car since Summer 2006

First and foremost there is NO overheating problem with the AC off.

- Aux. fan runs perfectly when the AC is on - aux. fan resistor replaced 1 yr ago
- Main engine fan runs perfect when the AC is on
- New Behr rad and BMW blue coolant - both done in 2006 <9,000km ago
- Water pump and T-Stat - do not know the history of these two parts
- Temperature gauge in sitting at 2 o'clock, not in the red zone though
- City driving; backs off a wee bit on the highway

So no problem with AC off, somewhat of a problem with AC on.

Any suggestions - have I overlooked something? Something I need to live with?

Blair...

nirvana19
06-22-2008, 02:56 PM
change the thermostat first, its cheap and very easy to replace (as long as you don't snap the bolts on the housing that is) and has a tendency to cause all sorts of weird cooling system problems. if the t-stat doesn't fix it verify that the fan clutch is good.

bimmo_2007
06-22-2008, 05:01 PM
Check the radiator vent hose & it's hole in the expansion tank -tiny hole- as it could be clogged with grime which causes overheating issues.

angusbn
06-22-2008, 05:55 PM
Perhaps I'll replace the t-stat - the fan clutch isn't the culprit if the engine fan is running OK?

angusbn
06-22-2008, 05:56 PM
The rad vent hose is the so called "pisser hose"? If so, I'll disconnect and check - the tiny hole in the expansion tank wasn't clogged.

bimmo_2007
06-22-2008, 06:31 PM
The rad vent hose is the so called "pisser hose"? If so, I'll disconnect and check - the tiny hole in the expansion tank wasn't clogged.
yeah it is the "pisser hose" :D