Question about 1987 Porsche 928

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Radiator over heating problem

When I run my car for about 10 minutes the overflow resovior keeps bubbling up, and the heater indicator needle keeps climbing to hot everytime. I don't know how to bleed the system incase there is an air lock.

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If you hve water bubbleing while engine is running 5 will get you 10 that you have a blown head g asket ,suggest you go to radiator sevice centre,they can pressure test it and also have device to tell you if you have exhaust gas in the coolant. wont take more than 5 min. then you will know exactly where you are at...
youdoit

Posted on Jul 29, 2009

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You did not say how long have you had this car or how much experience you may have with Porsche (especially the 928) cars. So here are some comments for your consideration based on my experience:
I have had a 1987 928 S4 for a LONG time.
If your car is overheating:
1 - you may have a radiator problem (restricted coolant flow due to "crud" in the radiator. Someone may have put radiator stop leak etc. in it, or poor quality coolant over the years created deposits. - have a radiator shop test the radiator "flow". If someone has put in "normal" coolant and NOT the phosphate free (preferably Porsche coolant) you will develop a problem over time.
2 - your electric fans may not be coming on - you can see this by visual inspection.
3 - the "flaps" in the front of the radiatort may be stuck in "closed position" thus not allowing sufficient air to flow across the radiator.
4 - you may have "stuck" thermostat.
5 - you may need a new water pump - this is probably your problem because they were known to fail especially if the car is NOT driven regularly. Your Porsche dealer service shop OR an independent Porsche service shop should do this for you - it is fairly comlicated procedure. While you are there - change the timing belt and rbuild or change the belt tensioner as well. Then drive the car.
CAPT Z
1987 928 S4
1995 928 GTS 5-spd
1999 996 Carrera

Posted on Feb 27, 2009

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