I am working on a 57 Thunderbird. I’m trying to find out is if I’m using the correct sending unit all of part houses pull up is a TS4 from standard products. If you ground the gauge wire it goes to full cold and if you leave it open it shows full Hot with the key on for both. I took the TS4 and grounded the outside of the sander and hooked it up to the gauge wire and put it in a cup of ice water the gauge will go to full hot Take the sander out of the ice water heated up with a heat gun and it goes to for cold I am certain that I had the wrong sending unit as I have checked all of my wiring and it is correct Most gauges I’ve always worked on when you ground them they go to hot not cold Does anyone know of a sending unit it basically works backwards than most it has to be quarter pipe thread Any help will be greatly appreciated
If grounding the gauge deflects the needle to cold then that implies that the needle rests on hot with ignition off. If that is the case then you have the wrong gauge. Correct 57 gauge should rest on cold. Apart from a slight difference in color the '56 Ford passenger gauge looks the same. but rests on hot. All other pre '56 Ford temp gauges also rest on hot but would need changing the faces and needles to match the Thunderbird instruments. All pre '57 senders have a set of contacts in them which are open until power is supplied and then the needle will go to cold. The '57 sender does not have that feature and as it does not know the position of the needle it works to deflect the needle as the temperature rises, in your case from hot to cold. Of course if I am wrong about your gauge and it does rest on cold with no power then disregard everything I have said.
The temp gauge is a thermo-electric gauge and works on a pulsating voltage of approximately 5 volts. The sending unit is a thermistor that has high resistance when cold and low resistance when hot. That means that as the engine temp goes up, the sensor gets closer to a ground. Since the gauge has a heating element to bend a bi-metalic strip, I don't think it cares about polarity. I'd give you ohm specs on the sending unit, but my 57 Ford manual doesn't give them. If grounding the sending unit wire causes the gauge to go to cold, you definitely have the wrong gauge. We are talking about the stock gauge in the dash, aren't we? GM products use balanced coil gauges and the sending units do work just the opposite. However, the resistance range would probably be wrong for your gauge. I have a 57 T-Bird and that's how the gauge works in it or at least how it has for the last 24 years.
Lots of good info here. The only thing I can add is to give Casco Thunderbird a call. They are parts dealers for baby birds and also have a restoration shop , they know these cars and may have some insights . The restoration division phone number is 740-622-9700 .
The other place you could try is Mo-Ma Manufacturing in Albuquerque , They are gauge restoration specialists. 505-766-6661
Rock Auto part listing https://www.rockauto.com/en/catalog...oling+system,temperature+sender+/+sensor,4748 Phil
Sender must ground to engine. No plumbers tape, etc on threads. Engine must ground to body. Temp gauge must ground to body or engine. Without good grounds the gauge will not read correctly. Phil
Cleaned block where the temperature sender goes in Cleaned all of the ground connection even the battery terminal to the firewall.
A 1957 Thunderbird temp gauge rests on cold with the key off. The '57 T-Bird temp system consists of three parts, the gauge, the voltage regulator, and the temp sensor. You possibly have the wrong gauge. '57 T-Bird temp gauges are very pricey. One on e-bay now for $ 350.00
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