Took my 92 500sl for a spin today when the sun was shining and noticed that the temp was staying at the bottom 40 deg area, drove for 1/2 hour and then it went to 85 deg area, then back to 40 deg and 85 a few times. Whats the deal? Gauge going bad?

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Thanks, Juan

Bad connection at the sensor is first suspect...clean the terminal..they get dirty due to their location............

what is the physical location of the sensor? front? rear? of the engine. Under air filter stuff?

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Thanks, Juan

Looks like this. Should be at the front of the engine, near the thermostat housing.

thank you gentlemen. ill check it out as soon as the temp cools down.

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Thanks, Juan