Overheating?

[jerl]

I recently bought a 1984 944. Just finished replacing water pump, belts etc. The car had no thermostat. I put a new oem stat in. Added coolant, drove 1mi, turned around. Before I could get home it overheated. Found out the cooling fan had a bad connection and was not working. Ran it again, now it goes up to the next mark past half, then the fan comes on. I have no idea what temp that is and if that is too hot. Does anyone know what the actual temp is at that point? I bought the stat from Pelican, but I really don't know its temp either, just that its oem. Thanks for any help on this.

[krystar]

as long as it stays out of red zone, you're good.

fan turns on at 3/4 mark and should drop it to under the 1/2 mark. fan only does this when car is sitting still. when car is driving at speed, temp shouldn't go much higher than 1/2 mark.

if you're experiencing hotter than 1/2 mark while driving at speed, rebleed the coolant. it can take several rebleeds to get all the air out. turn on the heater to full hot also

[John_AZ]

If the car came with no thermostat, how do you know what temp to use?

The thermostat should be matched to the radiator fan switch.

I would back flush the radiator and clean the fins of the radiator and condensor ---from the fan side not the grill side. If you do it from the grill side you are pushing the dirt further in the fins.

Use a cheap flush for the engine and radiator. NOT a HD Prestone type. The HD will cause more leaks in an old car.

Get a radiator pressure tester (rent with deposit at AutoZone or??) Put in 10 pound of pressure and check for leaks.

Do you have a OEM Porsche radiator cap with the correct pressure?

Use only a Wahler or Behr thermostat. A napa /AZ/ Oreilly is not the same and will not work right.

If you live in a hot state like I do, I drop the temp of the thermostat and fan switch.

~82C* is normal---I run a ~75C* combo.

It might be the radiator is plugged and the only solution is a rebuilt or new.

My temps on both cars stays under half in summer +110*F

GL
John

[nynor]

i would rebleed the system and see what happens. if that doesn't fix it, i'd check the temp switch at the top left of the radiator to see what temp it opens.

[smokin_944]

A couple of things. 1) The 3/4 hash mark is 97*C on a Series 1 car. That temp is within range according to the WSM. 2) You mention only 1 fan. Are we to dedeuce that the car doesn't have A/C? This is important because if in fact the car has A/C there are other points to consider. John_AZ has a valid point to consider, Wahler or Behr thermostats are the only way to go. The same applies to thermal fan switches. Keep us posted.

[John_AZ]

Originally Posted by jerl

I recently bought a 1984 944. I bought the stat from Pelican, but I really don't know its temp either, just that its oem. Thanks for any help on this.

I just reread your original post. Thanks for supporting Pelican.

If you bought the 944 106 129 05 thermostat it is 80*C (176*F). It is stamped on the bottom. Some sellers may ship 83*C (181*F)

This should match the fan switch on the radiator if OEM.



Nylor has a good suggestion. Burp your cooling system.
Lift the front of the car as high as you can.

Open the bleeder and get more air out. Air gets hotter than coolant and the temp guage will read high.

If this does not help, reread my first post.

GL
John

[jerl]

Sorry, screwed up posting. The thermostat is the Wahler you show. The radiator cap is Porsche oem. The car does have a/c and two fans, but I thought I read somewhere that one works with a/c? I will clean out radiator fins and raise the car to bleed some more. I have to readjust the balance belt anyway, its whining. At least I have an idea now what temp the marks on the gauge represent. I hope the engine is ok after overheating, it was into the danger zone. After fixing the fan switch connection, it was sitting idling when we tested it. It went to 3/4 , the fans came on and brought it down. I just wasn't sure what's supposed to be "normal".

[smokin_944]

Hey jerl, 2 things trigger both fans on a Series 1 car: turning on the A/C and/or a high temperature condition. Now that the fan(s) situation has been sorted out you can fine tune the cooling system. Good luck with the job.

[jerl]

Finally had some time this weekend to work on the cooling system. I raised the car and kept bleeding the system, worked great. I also blew out the radiator. Car runs a little over half on the temp gauge while driving. I'd say that's good, but one thing I've noticed, the gauge will jump up to the next mark and just as quickly jump back to where it was. Maybe a bad ground? I have not went over my ground connections yet.

[smokin_944]

The early cars are notorious for bad grounds. At some point it would be a good idea to go over them (the ground points) and clean them or even replace some of the ground cables.