[Chucksta]

I recently went through the same thing with my '97 SVX, except it was the opposite... my temp gauge said I wasn't getting up to temp. 1986Nate and Tapani gave me some great direction to track it down. I also changed the thermostat ( and found out that it needs to be installed "right side up"). It was eventually determined by a OBD 2 code reader with a "live data" function that all was within specs. I had basically the same readings as you are seeing, it was the single wire temp sensor that had slowly ( over the space of a couple of weeks), decided to re-calibrate itself.

The idea that the temp gauge has a "dead zone" was a little hard to wrap my head around... but the explanation that car owners don't necessarily want to see it moving around makes perfect sense. Today, virtually all cars use electric fans, which means in traffic, the temp will go up, the fans will come on, and the temp will go up.. and the cycle will repeat. If you're used to seeing it at one specific point ( like you were), you'll pay attention / notice it more if it moves, but for most everyday driving, it just sits in the "dead zone" as the coolant temp cycles up and down with road speed or fan function.

"Back in the day" .. cars commonly used a constantly rotating, engine driven fan, some fixed, some clutched, some flex, but all of them had one thing in common.. They would usually keep the coolant temp fairly constant. A rise in temperature was a definite warning sign.

Personally, I've decided to leave my sensor alone for now, I know from the code reader what gauge reading correlates to what temperature, and I don't mind seeing it go up and down as the fans go off and on. The OBD2 reader sits in the glove box if I ever want to get a second opinion on the gauge reading.