lu21780

Hello to all! After a while without a Vette I'm back in the game with a 1990 Automatic Coupe it has 140,000 miles on it. I purchased the car in January of this year it needed ALOT of cosmetic work but mechanically very good. It took me a month to finish and get on the road and so far do good until yesterday. I noticed my analog temp gauge get up to 260 I flipped out and pulled over it dropped and got home but it was still at an "uncomfortable" temperature. I spent most of last night looking through the forums for solutions and read about bringing up the temperature on the A/C Control panel. This morning I set the A/C panel to get my temp reading and the highest it got was 113c + 235f on the digital but the analog was higher. So I get to my shop and thought about switching out the Temp sensor on the right side of the head by the spark plug since it feeds the analog gauge. Changed it and did a coolant flush and cleaning between the radiator & condenser which was clean anyway while I was at it. Heading home was the same deal I had the analog gauge pretty much at 260 or a little under for most of the bumper to bumper 14 mile ride home while watching the display on the A/C panel go no higher than 113c = 235f. The car has no leaks at all coolant or otherwise, fans are turning on correctly the left one at around 225f and the right one with the A/C, Thermostat is opening at around 180f, and now I have a new Coolant Temp Sensor. The wire for the sensor doesn't look to be damaged as far as I can trace it (Which is not far), There is no obstruction of the radiator. What else should I be looking at? Is there something else that could be causing this problem? Bad sensor wire? Faulty gauge in the cluster?
Please anybody help!

PS: I have a spare cluster for a 90 I bought because I needed the LCD screen but the rest of the gauges are intact so if it is a gauge and if it is possible the swap out I have the parts to do so.

Thank you all for reading this way too long post

vetteoz

Engine temp as indicated by the digital display is fine.
You only have a problem with the analog gauge

Most likely
Disconnect the temp sender ; put a DVM on the wire (key off ) and see it it goes to ground indicating a faulty in the wiring

DinoBob

Analog gauge is famously inaccurate.