Temp gauge at 3rd mark or above
 

83 944 n/a

Hey all, new to the forum. Been dealing with overheating issues on my 944 for a few days now, seemed endless. What I've done: Replaced thermostat 180f, replaced thermofan switch 87/92, bleed coolant extensively. What I think I did wrong: trust the temp gauge.

Ive been constantly thinking I was overheating, I would be at 3/4 mark and push into the danger zone. Basically threw parts at it, and couldn't come up with a fix. Brought it to a buddy with a shop and he helped me bleed it because I was convinced air had to be stuck somewhere. Still running hot. Then we hit the upper and lower hose with a IR temp gun. Upper hose showed around 175-185 farenheit. Right in the sweet spot right? lower hose was a bit lower, around 150. And when the gauge was reading over 3/4 (97c plus) the block were the sender unit enters was reading 90c. So is it safe for me to say im not overheating in actuality, and my gauge is reporting wrong? These temps all sound like normal operating temp and car should be safe to drive? Gonna order new sending unit as well as clean grounds on gauges. Thoughts tho? Thank you!

Good catch... lots of wasted time spent chasing overheating when a check with an IR gun will show that there is no problem.

Thanks for sharing. Good to know. IR guns are pretty reasonably priced now, I have been planning on adding one to my toolbox too.

The needle can be twisted on the gauge head to adjust/calibrate, too.

I think there is some nuance on *when* you are overheating. Is it while the car is moving or while the car is sitting still? If the temp gauge is just constant at the 3 tick mark, thats one thing, and you may be correct in your belief that its the gauge or the sensor.

However, if the temp is rising while sitting still, but dropping while moving, to me that indicates an issue with your fans. Issues related to the fans can be narrowed down to a number of causes - thermo temp/fan switch (already fixed) on the radiator, fan relay, fan resistors, or the fan themselves.

I think it would be worth understanding more about when the car is showing as running hot, and if running hot only while sitting still, investigate the fan systems I listed above. Clarks garage has a really good walkthrough on the process of diagnosing these issues.

http://forums.pelicanparts.com/uploa...1630027882.jpg

One has to hate the honesty of the 924s/944 temp gauge. Your IR gun is telling that you don't have to worry.

Reviving my own thread here. I think I might be making myself go a bit insane with this stuff ! I just installed a new temp sender into my block. Oem Porsche one. My question is, is the temperature of the radiator hoses a good indication of the running temp of the car? Or should I be taking measurements on the block as well ? The top rad hose always is around 180F. While the lower rad hose is around 130, my question is, if the lower rad hose is 130, is the thermostat ever opening? Because that lower hose is very cool to the touch! New tstat installed and tested prior to install. My gauge still reads high even with new temp sender. Should I just continue to drive the thing and trust the temp of the rad hoses?

Once you verify that the temperature is actually, you can relocate the needle on the dial. But that would be my last resort. Maybe someone took the gauges apart and didn't mark or put the needle on in the same place.

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The hottest place on the engine will be the head at the base of the hose connection. This should tell you how much your gauge is off.

Make sure the cooling fans are running properly, too. Watch the temps' when the fan comes on and when it turns off. The first time the fan comes on the temp will be a little higher. Also make sure when driving at steady speed that the temp stays where you want it to be based on your gauge reading.

There are two cooling fans and two speeds. Check Clarks Garage for the details. Cooling Fan Operation and Troubleshooting

Was also going to ask about the fans. Do they run? Do they bring the needle down? My car has the same early style temperature gauge and the thermoswitch on the radiator for the fans is also 92/87, which you say you installed. My fans activate when the needle is slightly to the right of center. What are your fans doing?

My box stock 85/1 at idle causes the needle to creep slowly up to the third tick, fans come on, cools down to the first tick, fans off. Repeat ad infinitum.

Fans are working as they should it seems. Both come on high speed, new thermofan switch installed

That water neck, that has the bleed screw attached; comes in on IR gun at 90-92c. Is that a good place to measuring from? Because some areas of the engine are hotter. Like the block measured near the spark plugs, or the cam cover (the one that says Porsche on it, sorry don’t know exact name).

Yes that is probably the hottest spot in the cooling system.