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My Starboard Temp gauge started to peg out last year during sea trials. This would happen upon start up not something that would gradually climb. The engine ran great and was cool to the touch so my question is; would you suspect the gauge, the sender, grounding, wiring?
Thoughts?

Thanks guys,
Mark

you could switch wires from the good temp gauge from the other side to check it maybe

If the engines are running properly, I would check out grounding first, the sensor second and the gauge last. The easiest way to check the sensor would be to switch it with the one from your other engine. The immediate hot reading makes me suspect a ground wiring problem or debris touching the sensor and shorting it out. Walter

Thanks guys, will do tonight,
Mark

Mark...

When I bought my B33 with twin diesels both temp gauges read high.. one showed about 205F and the other about 200F all the time. I was worried about the high temps but since both read nearly the same I suspected some crud build up in the raw water systems of both engines since the previous owner had not used the boat much for several years. After having both raw water systems cleaned with RydLyme they still read the same. I reversed the wires and had the same results. I finally broke down and bought for about $60 an infrared thermometer. I scanned it all over the cooling system components and read +/-185F everywhere. To be safe I replaced both temp sending units and temp gauges.. and bingo.. both read 185F. So.. for some reason both sides read high. I might not have needed to replace everything, but it was cheap peace of mind.