overheating

[stogie25]

So I was driving home today when my AC turned off. When I looked down I noticed that my cooling system was overheating. I was close to home, so I headed here. The fans that usually kick on when I shut down the car did not kick on. I waited a few hours for the car to cool down and did some testing. The fans turn on when the A/C is turned on. They do not turn on otherwise. I borrowed a relay from a friend and the problem remains the same. The fuses are good. I am thinking the thermoswitch. It is an '88 944 n/a.
Any suggestions are appreciated.

[John_AZ]

Short answer, replace the thermofan switch.
Normal temp is about 87-92 degrees. Best for emissions. Watch out you do not strip the plastic tank threads.
If you do...JB Weld is your friend.

Tighten the overflow hose nipple. The crack easy.

GL
John

[stogie25]

Update.

This morning I replaced the thermofan switch, warmed up the car, and the fans never came on. I noticed that the radiator fluid looked horrible. When I jumpered the switch connector everything worked fine.

After a little more research I noticed that the hot coolant never circulated to the radiator, thereby never heating up the thermofan switch, and never turning on the fans. I pulled off the hose to the thermostat, and waited for a friend to help with the snap ring on the thermostat. We got it out, but noticed that the yuck in the radiator fluid was oil, and that the fluid stoppage was an oil clog at the thermostat. A little more troubleshooting showed that the oil cooler seal was bad, so the work began.

I ordered a seal, removed the headers and oil filter. I for some reason can not get the heat shield off of the oil cooler. Clark's Garage says to use a 10mm socket, but that is too small. The 11 is a little too big, and I can't get a vice grip in there. I sprayed some lubricant on the bolts, and am done for the day.

[John_AZ]

stogie25,

AAAAHHH,
Oil in the coolant.
It is a 10mm for the heat sheild.
Now you need to flush----------------------------everything.
Radiator-flush and back flush
Remove large hoses and run a cloth inside
Remove the coolant reservoir tank-flush

Tips on the oil cooler and OPRV:
Test the oil cooler----does it leak?
When you put the 2 large "O" rings on the oil cooler----put some oil on the "O" rings or they will roll over in the block and leak.
Clean the groove in the oil cooler housing----then use a thin layer of RTV copper or similiar.

Replace 2---TWO---"O" rings on the OPRV and get a new crush washer.

Put it all together and flush again and again with a squirt of DAWN dish soap and flush, flush.

Not done for the day--------it never stops

GL
John

[stogie25]

Thanks for the advice. I have to pick up my parts and a loaner alignment tool today after work. I think I will be doing a lot of flushing this weekend.

[stogie25]

So, parts in hand, I finally got to work on fixing the 944. The oil cooler seal is a nightmare of a repair, but it is done. It looks like it should be easy, but access is terrible. I somehow broke a lead on the oil sending unit, and the small hose that that goes to the heater core split. I will order them from Pelican tomorrow. That will give me a couple of days to continue flushing the cooling system, and get the thermostat back on. I can't find my big set of snap ring pliers, so I may need to buy a set. That will ensure that I will find my old ones.

I usually enjoy working on the cars, but this was a repair that even in retrospect I should have had done by someone with skinny arms. I am now firmly convinced that the 944 was designed by a room full of engineers trying to make it hard to service.

[Marajit]

Clark's Garage Message Board :: View topic - Oil Cooler Radiator Delete

[stogie25]

One last day of horrific repair. I had the car flushed and running well, but I forgot to put on the heat shield on the oil cooler. I decided to put it on today. The headers came back off, and six hours later the two impossibly inaccessable allen bolts are back in place, and everything is put back together. I still find it hard to believe the hours involved in trying and trying to put those two bolts in with absolutely no room to work. With everything running I am thinking of selling the car so I won't ever have to do that again.

[spec guy]

If you are at all thinking about selling, please contact.

[stogie25]

I am recovering from yesterdays ordeal. I have had a day to calm down, and even driven the car today. I put the cover on yesterday so I wouldn't have to see it. My fondness for the 944 (I can even type the numbers again) is returning. As long as I don't see the underside for a while I will hopefully keep enjoying the car. I usually enjoy working on the cars, but I hope this specific repair lasts a very long time.