Newbie...Gas and temp gauge dont work

[gamecock]

We just acquired a 1960 Thunderbird convertible. It is gold (Golddust? goddess gold? presidential gold?) and belonged to a family friend.

I want to fix the gas and temp gauge so that they work. Any tips on troubleshooting? I guess it could be:

1) Disconnected
2) Gauge faulty (can they be rebuilt)
3) Fuse?
4) Bad sending units in engine and in gas tank?

Thanks for allowing me to join your forum. A site like this makes DIY car repair a better experience.

-Andy
Duluth, GA

[Guest]

RE: Newbie...Gas and temp gauge dont work

I dont have my shop manual on hand.....Im in the process of painting my 58 and can you believe I taped it all up with the manual inside........but yes........of course they can be fixed. Its usually something simple for these are simple cars to work on and understand. I do suggest you get a shop manual for yours if you decide to keep it........believe me it makes things ALOT easier. Im sure you will get other responses ASAP. Happy BIRDING !!!!

[Guest]

RE: Newbie...Gas and temp gauge dont work

One of the first things I did when i got my squarebird was order and install a new gas tank sending unit, for the old one was rusted out.
Congrats on the bird !

[JohnG]

RE: Newbie...Gas and temp gauge dont work

I got a 58 hardtop a year ago and went through the same problem.

First you need to understand how the circuits work. You have 12V from the switch. It goes to a votage regulator on the back of the instrument panel. This is not to be confused with the item in the charging system. It it is a bimetallic on off switch which essentially turns 12V into about 5.5 V (average) which is the power for the two gauges you mention. This should be replaced to be on the safe side (or verified to work OK with a multimeter). They are about 16 to 20 dollars. The 5.5 V Dc goes to both of your two gauges and then to the sending units for each. The sending units may be thought of as variable resistors. The fuel sending unit, for example, varies from about 78 ohms (Emtpy) to about 10 ohms (full). At the end, both ground out.

If the unit puts out 12VDC all the time it is closed and has probably fried your gauges.

The ground should be checked and cleaned up in both cases. While in my case the temp sending unit screwed into the front of the manifold (behind the water pump) in fact I had no ground. I got around this with a short jumper wire.

You can see if either gauge has potential to work by disconnecting the lead to the sending unit and BRIEFLY grounding it out. The gauge should jump right up to either Full or P (for Hot).

The tank sending unit (easy to get to in the trunk under a little
black cover) may have corrosion or gunk and not grounding out. Clean this up to be safe. Be careful here as you will be staring into the gas tank while doing this!!

So at this point you want to isolate the source of the problem(s)- voltage regulator, gauge, sending unit or ground . A multimeter is very useful as are jumper wires.

You can easily buy a new regulator or sending units. If your gauges need rebuilding, such services are available (see Hemmings). They are not expensive but are slow.

During the winter you might send the regulator, gauges and sending units as a group and have them recalibrated for accuracy.

Good luck!

John