'69 Cuda temp gauge not working

[69 M-CODE CUDA]

Last summer when I first drove my Cuda after a pretty extensive restoration, one day my gauges seemed to be acting funny. I discovered that the temp sender wire and the alternator wire got too hot and melted their insulation together right where they lay on top of the passengers side valve cover. This is on a big block engine. I presumed that the reason this happened, is because I used a valley pan gasket with the ports blocked to reduce the heat to the intake manifold. This 'new' hotspot is exactly where it proved too much for the insulation.

So I replaced the melted sender wire, and enclosed the wires in a heat resistant sleeve where they cross over the engine. I also replaced the temp sender with a new unit.

Predictably, my temp gauge doesn't work any more, even with the new sender. The fuel and oil gauges still work, so I assume I probably fried my temp gauge? Is there an easy way to bench test the gauge? I plan to dig into this again this weekend, and just wanted to get some opinions from the experts.

This is on a '69 Cuda with the rallye gauges. Thanks in advance for any help.

 

[Murray]

Remove temp sender wire and ground it, does it peg the gauge? If not, then you have a wiring or gauge problem.

 

[4spdragtop]

You said "guages" so more than 1 acted funny?

 

[69 M-CODE CUDA]

You said "guages" so more than 1 acted funny?

Yeah, if I can recall now...this was last year, and I’m almost 66, so here goes; I think the fuel was reading too high while out for a drive, and then I noticed the temp gauge pegged to the right. Pulled into a friends driveway and then discovered the melted wires. Peeled them apart, taped them up and drove home. As soon as we separated the melted wires the temp gauge dropped to zero and has been there ever since. The fuel gauge returned to normal, and the oil gauge didn't seem to change at all from normal.

 

[4spdragtop]

You may already know the fuel gauge has voltage regulator inside it that "runs" the rest of . That may be an issue as well.

Yeah, if I can recall now...this was last year, and I’m almost 66, so here goes; I think the fuel was reading too high while out for a drive, and then I noticed the temp gauge pegged to the right. Pulled into a friends driveway and then discovered the melted wires. Peeled them apart, taped them up and drove home. As soon as we separated the melted wires the temp gauge dropped to zero and has been there ever since. The fuel gauge returned to normal, and the oil gauge didn't seem to change at all from normal.

 

[69 M-CODE CUDA]

You may already know the fuel gauge has voltage regulator inside it that "runs" the rest of . That may be an issue as well.

I do know that. I bought an IVR to replace that component while I’m at it.

So I disconnected the temp sender and grounded it. Temp gauge didn’t move, so I suspect the gauge is bad. Curiously when I grounded the temp wire, the oil gauge pegged full. I imagine that’s because both of these gauges are powered by that internal voltage regulator?

 

[RedFish]

I do know that. I bought an IVR to replace that component while I’m at it.

So I disconnected the temp sender and grounded it. Temp gauge didn’t move, so I suspect the gauge is bad. Curiously when I grounded the temp wire, the oil gauge pegged full. I imagine that’s because both of these gauges are powered by that internal voltage regulator?

Nope, grounding the purple temp sender wire should have no effect on another gauge. Oil gauge sender wire is gray. I suspect it may be melted to the purple wire somewhere in the harness.