Overheat

[divezic]

I have an '84 944 with 81k miles. Last weekend my wife and I were driving north
of Vancouver, BC, through the mountains to Whistler. The temperature was about 85 F outside and unless we turned off the air conditioning the engine would overheat at normal speeds (50-65 mph) going uphill. It would also overheat going 80-85 straight and level. Oil pressure inversely followed the engine temp (lower pressure with hotter engine). There was a considerable drop in engine temp when we turned on the heater. The water pump was changed 24k ago and the coolant was just changed.
Anybody have any ideas whats going on. What should I look at. Warm summer days with the heater on stink.

[Martin]

Check the thermostat is opening fully or just replace it.
Also check the electric fan switch in the radiator is working.

[Steve Taylor]

Your Radiator is clearly not doing all it should but the internal heater makes things better - this suggests to me a clogged radiator rather than a thermostat.
At speed you shouldn't need the fan (check the switch just in case).
I would look for a blocked radiator after checking the fan switch - usual stuff - cold area anwhere across the matrix just after a decent run out.

You could try putting something in the coolant that will remove the crud but with an aluminium engine I would be looking at a new or re-con rad pretty soon.

Steve

[Art]

If all the mechanical stuff checks out you might want to try the following. First reduce your coolant protection to ~-10 F. (Assuming you now have about 50/50 in the radiator, remove about a half gallon and replace it with plain water.) The add 7 ounces of "Red Line" water wetter (about $7 at most auto parts stores. My 84 wasn't exactly overheating but on the track it was just below the upper yellow bar. After the above procedure, it went back to normal.

Good Luck.

[warblade21]

Hi,

I am having the same problem as the guy from Canada. I have already replaced my bad radiator, and changed out the thermal fan switch. The fan kicks on at the right times and my car is still overheating. I haven't checked the thermostat yet. I have 88k miles and i need to change my oil filter. What do you think.

[zedsn]

After your radiator replacement are you sure that you got all of the air out of the system? An air pocket could cause you problem.

[carsontc]

wow...posts from 10 years ago !

divezic says he found his problem in this post:

http://forums.pelicanparts.com/showthread.php?t=10290