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The temp gauge in my girlfriend's car consistently reads hot, the car is an 89 244DL.
Here's the background:
Quite a long time ago the temp gauge would occasionally shoot up pretty close to the red pretty quickly, and then randomly drop back down to right at 9:00 again. The changes on the gauge always looked like they happened to fast to be accurate readings to me. This seemed to happen regardless of if the car was driving on backroads, moving quickly on the open highway, or sitting idling in the driveway. Recently it started happening more often, and the needle started to creep into the red, so I bypassed the compensation board. Now it consistently reads about 3/4 of the way to the red and just sits there. It doesn't shoot to the red as soon as you turn the key, so the wiring isn't shorted to ground; it reads cold when I first start the car, then climbs up to where it sits as the car warms up.
Other facts:
*The temp sensor is reasonably new, about a year old (though that doesn't mean it's not faulty)
*I've measured the temperature of the head and radiator hoses with an IR thermometer and found the temp to be between ~190° and ~210° depending on where I was reading, which I think is roughly normal operating temp (or is that incorrect?)
*The needle is steady at 3/4 to the red, almost as though there was a temp compensation board still in there telling the needle to stay exactly in that position, it doesn't seem to change when the car is moving 60MPH or idling in the driveway.
I think I can rule out a sticking thermostat since the IR thermometer measured temps between 180 & 210 degrees, correct?
What should the resistance of the temp sensor be at normal operating temp? I can measure the resistance with a multi meter. If it's not where it should be I'll replace it.
What are the chances that the gauge itself is bad, and how do I test it?
In case it helps, here's a pic of where the gauge reads: http://itconfuses.me/misc/HighTemp.JPG
Thanks for the help, as always!
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