Tetrylone

Temp gauge reads 230 but laser thermometer reads 210. Anyone else ever have this problem? Want to share some remedies?

tuxfan212

Well the laser thermometer is reading outside engine temp. Try reading it towards the rear of the valve cover where the gauge temp switch is. If it is still off you could replace the temp switch, the one in the back not the one right up front.

Tetrylone

Well, I've got an 88 and I'm pretty sure that the only sending unit was in the rear of the valve cover but I've since moved it to the thermostat housing (with the addition of the housing from a later model). But it still reads hotter than it actually is. I was measuring the temperature with a laser from two spots- the thermo housing and the expansion tank. Expansion tank reads 190 and the housing will - at its hottest - read 210. You did mean sending unit when you said temp switch right?

XJ Stryker

I really believe you are gonna have a difference in tip since you are measuring outside the engine and the sensor it measuring inside the engine. Even being metal it will have some insulation properties even though it is very minute.

Tetrylone

Agreed. But would it be that large of a discrepancy? 20-30 degrees is a ton of difference, I would only expect to see a variance of 2-3 degrees.

EuroJeep

I had this problem.
Spent Too much on parts and wasted time.

Finally I moved softly the needle to the right reading.
With my finger.

Do it right after turning the key OFF.
It matters not to do it when it is powered.

Now it is perfectly calibrated.