Thread: 1994 Pontiac Grand Prix - Overheating Issue - No fans?

I have a 1994 Pontiac Grand Prix SE with the 3100. I recently started having issues with it overheating. The car had 75k original miles on it 4.5 months ago but with a new job I drive long distances with this and put 35k miles on it in a 4 month span. I started noticing the intake gaskets were leaking a little.

Then noticed a slight over heating issue. The overheating was only noticeable in the city - one I got on the highway I didnt have the issue. After a week of this going on I decided to get a coolant flush and see if that would help. Well after the flush it made things worse. I noticed the fans weren't working (they were working thing summer I know that) When I unplugged the coolant temp sensor the fans came on - when its plugged in they dont come on.

So I changed the water pump, thermostat, and coolant temp sensor. The fans still didnt work and was still having a nasty overheating issue. I decided to do the intake gaskets. Got everything pulled apart and noticed the waterjackets were clogged up (believe from the coolant flush) I flushed the system for a while til nothing dirty was coming out. Cleaned out the radiator and got it all together.

Still having an overheating issue - both fans only comes on with the a/c on. The driver fan has kicked on once and hasnt came back on. Could the temp sensor on the rear head have something to do with this? Any suggestions where to go from here. Oil is fine and coolant is still looking good. No signs of a blown headgasket. My temp gauge fluctuates quite a bit from 210-230 and then drops back down to 180 then goes back up. Its really odd and I cant figure out why it would do this and why the fan doesnt work when the temp gets up about 210*

The sludge is from the dexcool degrading when it meets air usually from the bad intake gaskets w/ the 3100. I had that happen once and there was orange dex jello all over everything.
The AC will automatically turn both fans on.
Did you do a compression test to rule out a warped or cracked head?
You may just have major air in the system if it is fluctuating like that.

I didn't think pre 97 they used dexcool...

My guess is bad coolant temp sensor.

I had the same issue. I went and replaced the thermostat and put the new model water pump that pushes water more efficiently and it's aluminum so there for cools better. Next step is to check the AC temp sensor. It's located under and behind the intake cables poking out of the block. It's a pain in the ass if you have large hands but the best way I found to take car of that was with fishing needle nose pliers. Hope that helps.