1957 Thunderbird temp gauge issue

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dbt

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Thunderbird Year
1957
1957 Thunderbird temp gauge issue.
Temp gauge didn't work at all until I replaced the temp sensor in the block. Now the temp gauge goes almost to the hot setting after a short drive. Doesn't seem like the engine is overheating, water level is always good too. Can the sender be bad or possible a defective 62 yr old temp gauge?
 

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I am suspicious of the sending unit. When the car is cold, the sending unit should be basically grounded, just as if you grounded the sending unit wire to the engine block, so the gauge should read cold.

Do you have sealer or Teflon tape on the sending unit? That can cause problems. An easy test to see if the sending unit is properly grounded is to run a temporary jumper wire from the body of the sending unit to the engine block using small alligator clips and see if there is any change in behavior.


doug7740
1955 Thunderbird Blue
 
On my '56, I replaced the original malfunctioning temperature sending unit with a reproduction replacement. The gauge then read high even though the temperatures measured with an infra-red sensor were normal. I found and installed a NOS sending unit and now the gauge reads normally.
Jim Yergin
 
dbt said:
1957 Thunderbird temp gauge issue.
Temp gauge didn't work at all until I replaced the temp sensor in the block. Now the temp gauge goes almost to the hot setting after a short drive. Doesn't seem like the engine is overheating, water level is always good too. Can the sender be bad or possible a defective 62 yr old temp gauge?
Click to expand...
Of course there is the possibility that the gauge itself is defective. But if it isn't proceed...
I might ask another question; What does the fuel/gas gauge do? The two gauges; temp and fuel are regulated by a small voltage pulse regulator attached to the rear of the instrument panel. when it fails the temp goes to hot and the fuel gauge also give a wack reading. The previous poster/answerer noted correctly that the sender in the head should not have any sealer or tape between the sender and the head threads. That is the grounding. If you are still in a quandary you can install a second after-market gauge in the passenger side head. That requires removing the freeze plug/bung across from the original but on the opposite head. Install a new replacement bung. Do not use any sealer or other addition between the bung and the cylinder head. An aftermarket temp sender is then installed in the passenger side head. You will need to run a wire from the "on" side of the ignition switch to the second gauge and a wire from the gauge to the sender. Instructions should come with the new gauge. I also recommend an inline fuse for the gauge. from the switch. the gauge should also come with a mount that can be attached to the underside of the dash so you can view the gauge. In this way you have the dash gauge and a second, perhaps more accurate, temp gauge. Surprisingly my auxhillary VDO gauge indicates my original dash gauge is reasonably accurate. You can also follow Gil's advice that if it isn't boiling over it is fine.
good luck to you, J.
 
I agree that checking how the other gauges are reading, could be the behind the dash regulator. Is it grounded properly? many people fussing behind the dash have no idea how important it is.
 
Anyone have an engine pic or diagram as to where to look for the sender unit?
thanks.
 
OhioTbird said:
Anyone have an engine pic or diagram as to where to look for the sender unit?
thanks.
Click to expand...
If you refer to your shop manual that should give you the guidance you need. On all the sender is on the rear of the driver side cylinder head on the upward surface.
 
Thanks to all. My gauge has been pinned on Cold. It's my first task for Spring.
 
Bought the head sensor and replaced it yesterday. Temp gauge came up nicely and all is set.

Thanks to all for the guidance.
 
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