I just finished testing my temp gauge sender and it appears to read about 3C LOW at 100C based on the temperature/impedance curve.

 

Ernest, If you leave the ac off and do your test runs including idleing for 5 minutes or so does your car run cool or hot? If it runs cool then I personally think that the problem is not with your motor. My car also goes to the top white line in stand still traffic with the ac on, but while driving it stays in the middle. If I don't put the ac on at all then it stays in the middle regardless of traffic or not. What I'm getting is that Porsche made these cars as high speed crusiers not for sitting in daily traffic(my situation). My opinion is that the cooling efficency of our cars just plain suck. I agree with you that it's not normal for our cars to run this hot but the flaw is in the design of the cooling system. I hope I'm wrong and that your Genuine Porsche thermostat works. Can't wait for the Fall so I can take my car out, Reno

 

I can't believe you hadn't done this yet! All this time and money spent just to find out your sensor is off by 3 degrees Celsius (37.4 degree Fahrenheit)

Man I'm really disapointed in ya! Your buying the Crown at Sharkfest, you know that right!

 

T_Max,
That's SOME Farenheit scale you got there!! 3C=6F (roughly) on my scale!!
If I can get this sumbitch to run cool I'll drown you in Crown!!
Reno,
The AC makes no difference.

 

Heres what I checked against.

online temp exchange

 

They're correct. 3 degrees above zero Centigrade IS 37.8 degrees Farenheit, but 3 degrees on the centigrade scale at about 100C equals about 6 degrees on the Farenheit scale.
C=0 (freezing point of water) to 100 (boiling point of water).
F=32 (freezing point of water) to 212 (boiling point of water).

 

Did you chart your temp/oHm reads when you test the sensor?

 

Yep,
The gauge ohms out about three degrees LOWER than actual temperature at 100C. When the gauge shows 100C the actual temperature is 103C.

 

But did you plot it to see at what point it was off or was it true up to 100c?

 

The sender is accurate to 80C and then ohms high. I plotted the curve.

 

I can run cool all day with the gauge middle or low, but if I get stuck in bumper to bumper I "pinball ! ! !" and overheat. Would you guess bad TStat or Radiator?

 

Bad viscous fan coupling. (no air flow at idle)

 

GT
I agree with figgen. I'd guess that you have an air flow problem. Check out your cooling fans.

 

Hmmmm? I don't quite understand. The viscous (sticky) fan is running while the car is idling, which I guess is correct, as I have no idea as to its proper operation. It is moving a ton of air while turning.

Is this a centrifigal clutch system where at higher RPM the blades disingage?

 

GT,
You have the viscous clutch fan.
If your car is running cool at speed, with the engine revved up cruising along, your radiator is getting rid of the heat properly and your thermostat is also doing its job. The only difference in stop and go traffic is the air flow over the radiator. Your fan has more than one available speed and should be able to run faster when the radiator heats up. There's a sensor/switch on the bottom driver's side of the radiator that should control this. If the sensor/switch is defective, or if there is a problem in the circuit, the fans won't run at full speed.
You might try removing the connector from the temperature sensor on the top of your intake and bridging the connectors on the wire. That should cause your fans to run at top speed and let you know what top speed is.
I'm not very familiar with the 86.5 so I can't be certain how it works.