924Board.org

[canyonblaster]

S2 931

My temp gauge is registering at 3/4 when normal op temps. We replaced the sending sensor and although the gage is running higher than it used to the heat gun shows 190/normal.

anyone have an thoughts for me?
where does you temp guauge display normmally?

rest of system seems to be operating as designed, fans, etc.

Thanks!
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PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS

[Rasta Monsta]

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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[canyonblaster]

wow that seems really low temps, is that US degrees?
my car is runnig 3/4 and 190 from heat gun reading...

where on the gauge does your car run?
_________________
PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS

[emoore924]

Centigrade

Mine runs just to the right of center but does move around a bit depending on a lot of things like sitting still, running down the road, fans on, yadda....

[morghen]

Mine just sits at the mark Rasta says its 80°C
In hot summer trafic it moves close to the midle but then fans start and bring it back to the 80 mark.
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Supercharger and EFI kits
https://www.the924.com

[Rasta Monsta]

[canyonblaster]

yes that was a dipstick comment...

mine used to run at the first mark all day long but something changed and now it is running at 3/4, 190 F. system seems to be operating as designed...
_________________
PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS

[emoore924]

If you changed radiators and/or the fan thermo switch, you might have inadvertently changed the temp at which the fans turn on thereby raising the operating temp of the system.

Or it could just be the radiator is clogged with crud.

[Ponz]

79 turbo stays at 80 degrees.
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77 1/2 track car
79 931 Euro
87 911 Targa

[ideola]

"Normal" running temp will depend on which fan temp switch and thermostat combo you have in the car. As others have noted, these need to be a matched pair, and you or a previous mechanic or owner may have installed one or the other of those with an incorrect temp range.

The standard setup is 87C t-stat and 92C temp switch. In my experience, on a properly operating cooling system in "normal" driving and relative warm ambient temp, this will result in the fans not switching on until you hit the third tick mark. So "normal" reading will be somewhere between where Rasta has indicated 89C and 97C on the gauge (which stands to reason when you look at the temp range on the OEM / stock recommended temp ranges).

The problem with the OEM setup (again, in my experience) is that it can lead to heat soak and runaway temp which can be difficult if not impossible to bring back under control, especially on hot summer days.

I have switched all of my turbo cars over to 75C temp switch paired with 82C t-stat. The astute reader will note that the stock setup has the t-stat colder than the fan switch, while my preferred setup does the reverse. Some have postulated that doing so will cause the fans never to switch off. However, in practice, that is not at all the case. With this setup, my normal running temp hovers just above or below the 80C (first tick mark), and the fans always kick in the moment the needle touches the 89C (center tick mark). The fans will run until the temp drops below the first tick, then shut off and stay off until the temp once again reaches the center temp mark. While driving with good airflow over the rad, the temp rarely exceeds the first tick mark, so the fan rarely runs while the car is moving. This behavior is attributable to the cooler temp range of the t-stat and a properly operating cooling system with proper water-glycol mix and water wetter.

Another benefit with this setup is that you KNOW something is amiss if the fans don't kick in by the center tick mark; this setup has alerted me to failed wiring on the fans on at least three separate occasions where I otherwise would have been guessing and anxiously watching the temp needle move toward the red. Some have also postulated that my preferred setup will cause premature fan failure, but I have not experienced a single fan motor failure on a 924. Ever.

The only detriment I've discovered to this setup is that it is very difficult to get cabin heat when outside temp is below 50F. But I drive my cars so infrequently in really cold weather that it has not been a problem for me. If I were forced to press a 931 into year round daily driver duty, I would simply swap in the "cold weather" warmer range combo during winter.
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erstwhile owner of just about every 924 variant ever made