Hello, fellow Porsche owners! My girlfriend recently purchased an 85 1/2 944. It is a beautiful car, just needs some well deserved TLC. There are a couple of problems which I am working at this time, she had it overheat recently. I decided to put a new thermostat in it, and noticed there is sludgy oil coming out of what appears to be fairly new antifreeze. So, after doing a little searching around, it appears as though the oil/water heat exchanger may be malfunctioning - which I intend to replace also.
Now, to get to the topic of this email - could this part be what is causing the excessive heat in the passenger compartment? No matter what she turns the heater adjustments to, lots of heat is being put into the passenger compartment of the car. This makes it very uncomfortable to drive around, especially when it is hot out. I'm wondering if there is something else that I should fix or work on, or does anyone think this oil/water heat exchanger might be the culprit? Also, any tips on the replacement of the heat exchanger are certainly welcome!
Thank you, in advance, for any help or ideas!

 

i had some problem like that with a 87 944 ,even with the heater off i couldnt stop hot air in the cabin.
my problem was in the engine bay .a tiny vacum pipe was faulty or was leaking air as all the heater controls are run off the break booster . thr pipe is just in front of the break filler bottle . not sure the 85 model has the same commande system for heater controls

 

If you have sludgy oil mixed with the antifreeze, the oil cooler seals have gone, and you shouldn't be driving it until it is fixed. Make sure you change the oil and flush the coolant. The heat is most likely due to the vacuum line at the heater control valve or at the firewall from the heater control valve. 85 and a half will be the same, the heat is control via vacuum.