Temp gauge reads higher than reality

[opethmike]

For a while now, my dash temp gauge will read ~220 when both the output of my Megasquirt ECU and an infrared thermometer show that the coolant temp is really ~185.

I'm guessing that the temp sensor in the head is on its way out?

[Bitsyncmaster]

I just did some testing of the Temp gauge. Maybe this will help you test the parts.

http://dmctalk.org/showthread.php?15056-Electronic-Otterstat&p=220822#post220822

[DMCMW Dave]

For a while now, my dash temp gauge will read ~220 when both the output of my Megasquirt ECU and an infrared thermometer show that the coolant temp is really ~185.

I'm guessing that the temp sensor in the head is on its way out?

More likely the gauge itself, or the calibration resistor on the back of it. I've seen the calibration resistor fail on fuel gauges several times, not on a temp gauge. I've seem a couple of temp gauges that did what you are seeing, but never had anyone care about it enough to have us find the rood cause once they understood how to do a brain calibration. Drives me nuts to see that though. Can't say I've ever seen the sender fail, it's pretty simple. They usually get replaced due to rust on the connection.