66 Cuda Temp gauge issues

[firemans66cuda]

yes I recently purchased a beautiful 66 cuda and everything worked fine but when I had a radio installed I had the guys at the radio shop installed new cluster lights. Well the temp gauge was not working when I picked it up so I took it back and they said it was the gauge. I bought a new gauge and when they went to put it in they said a "stud" was loose so they tightened it but now they fuel and temp gauge is pegged out and they have no clue why. Great guys and I have never had a issue with them but if some one could it would be much appreciated..

 

[KitCarlson]

Sounds like a problem with the instrument voltage regulator. It regulates battery voltage to about 5V. It is likely gone bad, or the output is shorted to a 12V supply. Since work has been recently done, wiring may be the fault.

There are many posts if you "search" for instrument regulator. There are replacements available, low cost DIY using linear regulator, improved solid-state switch mode regulators, and the old style vibrator style.

 

[Rocky_JS]

Yes, Voltage limiter in that gauge assembly is inside the fuel gauge and feeds the temp gauge. when it goes bad in your case it is sending batt voltage to the gauges.

you will need new or rebuild fuel gauge, and add an updated external Volt limiter. for now disconnect the temp gauge at the sending unit so as not to burn the new gauge up if not already.
contact Ben at http://www.demonivr.com/ He is a member here and extremely helpful in these matters. He can rebuild your gauge(s), calibrate, and set you up with a new external VL.

 

[RedFish]

Last panel I serviced was a 66 B'cuda with nearly the same problem.
The mounting and contact studs on the gauges are swedged into a piece of fiber board. That board slowly hardens, distorts, or gets water damage, whatever. Tightening the nuts will eventually separate the stud from the board and ruin the internal workings of any gauge.
You really cant blame someone who went in there to replace bulbs if and when other 45 year old stuff falls apart.