BMW 5-Series E34 (1987 - 1996) - (1989 535i) - Over Heating

Honest John Back Room » Technical matters
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Sat 18 Aug 2007 22:29
(1989 535i) - Over Heating - temp
Hi all,
I have a BMW 535I on a G Plate the car is overheating badley, when you drive the temperature is ok but on tickover it boils up and the needle goes into the red. I have had the head pressure tested and a new head gasket fitted Plus a new Thermostat , the water pump has been checked and is ok .
I have tried filling the cooling system useing a proffesional device that removes all of the air. When it does overheat all the pipes go hard due to the pressure. the heater works fine so i am at a loss as to what it can be.
Any advise. Temp
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Sat 18 Aug 2007 22:36
Over Heating - injection doc
is the viscous fan working ok? they tend to fail as the coupling goes weak to although the fan looks as if its rotating it doesn't pull enough air through the rad. when the engine gets hot the fan should roar when you rev it up? it could be the rad is poor and doesn't allow the heat on to the viscous fan unit as the unit is thermostatically controlled then the coupling wont work
regards Doc
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Sat 18 Aug 2007 22:55
89 BMW 535i - Over Heating - Screwloose
temp

Make sure that your viscous fan coupling is locked when it's hot. That's quite common. Does the electric fan come in?

The water pump impellor can also come loose on it's shaft and cause all sorts on these.
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Sun 19 Aug 2007 01:50
89 BMW 535i - Over Heating - Aprilia
You must have spent quite a bit on this already (head job etc!).

Anyway, given what you have spent I would swap out the viscous coupling and the waterpump - they are not expensive and they're easy jobs.
Also check out the little pipe that runs from the top of the thermostat housing to the header tank - it can get blocked and stops the system bleeding properly - if you get an airlock around the thermo housing then it will inhibit flow.

Pipes going hard could be head gasket leak - are you sure is not blowing again? Look for bubbles in header. A lot of these M30/35 BMW heads go porous or have small cracks in them.
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