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bill d cat bill d cat is offline
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Join Date: Jul 2003
Posts: 21
Late 944 Temperature Gauge Calibration

On Saturday I was stuck in some awful awful awful beach traffic and "noticed" my climbing temperature gauge. Never overheated, not much past the second white line at all but scary, since on the highway the needle is usually lined up in it's Prussian best with all the other needles, exactly 1/2 way up the gauge. So Sunday I spent a delightful day losing nuts and bolts into the nooks and crannies of the 944 motor, breaking washers and going through the Clarks Garage cooling fan diagnostics. It passed, at least I think. I was actually SHOCKED by how much air is moved by the cooling fans on "high", I'm sure the fans have gone to high speed only rarely while I've owned the car.

I attempted to research what, exactly the various markings on the 944 temperature gauge actually MEAN, and exactly when stuff is supposed to happen.

Here's what I came up with:

Bottom of broad white line (40C)
Top of broad white line (60C)
Low temp 160F Thermostat opens, if so equipped (70C)
First thin white line (80C)
OE Thermostat opens (86-89C)
Thermo-Switch (92C) ON cooling fan low speed operation
Second thin white line (100C)
Thermo-Switch (102C) ON cooling fan high speed operation
Bottom of red zone (115C)
Top of red zone (call AAA and tell them flatbed needed)

What I'm concluding from this information is that my car is operating, more or less, as designed.

I'm also concluding that about 3/4 of the range on the temp gauge is devoted to absolutely useless information, ie. "it's not warmed up yet" and "the engine is melting".

Only 1/8 of the range of the gauge is devoted to the span between normal operation (cooling fans advance to high speed at 102C) and imminent disaster (the red zone at 115C).

So my question, the answer to which is probably lost in the Porsche factory records from the 1970s is: "Who's idea was THAT?????" and "WHY?"
Old 09-01-2003, 04:24 PM
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