1937 Dodge D7 Temperature gauge reads high

[mrtechnologist2u]

When cold the gauge reads ~120 F.  When car is warmed up car reads 212 F.  When driving 50 mph it reads just above 212F.

Output of Radiator coolant into engine is 148 F

Highest temperature anywhere in engine when reading with ir probe is 160 F!  

Heater core is warm

The Low temp reading on the gauge has been offset for some time as there is a mark on the gauge face at that point.

There are no kinks in the capillary tube to the gauge.

 

What could be causing the offset.  Could there have been an overheat at some point that caused ether to condense in the gauge head?

Think thermometer that has a gap in the capillary tube of mercury or red alcohol.

If that is a thing, could it be corrected by putting the sensor in a salt and ice bath to draw the ether back into the bulb? 

 

Any thoughts would be appreciated.

[Pete K.]

Good question, All I can add is many years ago I had a 1930 Buick that had a similar problem as yours. I took the gauge out of the panel and pried the back of the gauge off, the whole time trying to be very careful not to over work the capillary line. There was a "bellows" inside that was geared to the needle. I took mt fingers and slightly bent the bellows back into the original half-moon shape, noting the needle would now point to cold, when cold. Put the whole thing back together and low and behold, it worked for the next 19 years I owned the car. You need a lot of finger dexterity and no shaky hands for this operation as I recall. I did this 47 years ago.

[mrtechnologist2u]

Thank you Pete!  I now have another way to look at this problem.  While my hands are not that shaky I am a big boy with tree stumps for fingers. 😄   I do not look forward to to trying to extract my temp gauge from the instrument cluster while under the dash!  But if I have to, I have to!

[Alan Cutler]

I was told the tubes are filled with ether...therefore gaps will not effect the reading.