1939 Ford tudor Temp gauage

B

billybronco1

Well-known member
What would make the original temp gauge be maxed out all the time, never changes always red to the top? Can it be fixed or does everything from the engine to the dash have to be replaces and are the parts available someplace?
 
An open circuit will show full hot. If it has the two senders, one in each head, one is an on-off switch. If it is off (open circuit) the gauge will show full hot. So would a disconnected wire.
 

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1939 has a mechanical temp gauge, no electrics in this one. It consists of a bulb in the head, a visible glass tube in the dash, and a small tube connecting the two, all filled with a heat sensitive liquid that is not available today due to being banned by the feds. The system is the most accurate of any type, but if damaged, as yours likely has been, lots of luck. Some guys say they are happy with repaired units, but I wouldn’t think a repaired unit could ever match the quality nor the longevity of an original, which are still available if you got the green.
 
my 39 was that way after it was stored laying flat, during restoration. The mercury was separated by an air bubble. After years of driving I saw the air lock move up to the top of the gauge. I did nothing to make it move. The heat and cold cycles must have moved the bubble. It reads normal and is fairly accurate. I would drive it and keep an eye on your temp, good luck. 39's did not have electric gauges for temp.
 
I found it strange that is is pegged, If broken seems it would not register at all. Almost sounds like an air bubble has pushed to the max. I'm wondering if I try to cycle it hot and cold if I could get any change in it. Boil it freeze it type thing.
 
I have had them pegged before and that particular one was shot.Try freezing first.If it goes down you might get lucky.
 
ford38v8 said:
1939 has a mechanical temp gauge, no electrics in this one. It consists of a bulb in the head, a visible glass tube in the dash, and a small tube connecting the two, all filled with a heat sensitive liquid that is not available today due to being banned by the feds. The system is the most accurate of any type, but if damaged, as yours likely has been, lots of luck. Some guys say they are happy with repaired units, but I wouldn’t think a repaired unit could ever match the quality nor the longevity of an original, which are still available if you got the green.
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Yes, I should know better! Same as the 38, I was thinking 40.
 
First try boiling it in water with the gauge raised. The hope is the fluid will expand to be together. Next I have gotten some to get well by tying a string around the gauge and whirling the unit in a circle with the sender on the outside of the centrifuge. Do it for a few turns. I had one hanging down in the basement for 5 years before it freed up. And a NOS one wrapped in a coil in its original box which was still good.
 
Juergen said:
First try boiling it in water with the gauge raised. The hope is the fluid will expand to be together. Next I have gotten some to get well by tying a string around the gauge and whirling the unit in a circle with the sender on the outside of the centrifuge. Do it for a few turns. I had one hanging down in the basement for 5 years before it freed up. And a NOS one wrapped in a coil in its original box which was still good.
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The centrifugal force method should not be done with the unit unsupported. If attached solidly to a long pole, it can be spun round with no stress applied to the copper tube. I did this, which did prove successful finally, after suspending vertically with a vibratory on the sender tube for a week, which did nothing. The message is, air bubbles may develop anywhere the tube loops up then down, both in storage and in use on a car.
 
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