Okay, I was installing windshield washer hose on my 1966 442 to get the washer working. In the process, I found a wire with the insulation melted. Going by the Service Manual, it appears to be the engine harness feed (red wire) from the junction block back to the harness near the fuse block. The insulation is melted off the wire for that whole distance. What do I do now? Everything seemed to be working fine since I got the car a couple of weeks ago. Had some blown fuses (radio, and later additional gauges) that I replaced and all worked fine afterward. Don't want to get back on the road like this. Where should I start to locate the problem causing this wire to heat up enough to melt the insulation? Thanks!

 

You don't know that you've got a problem that's "causing this wire to heat up enough to melt the insulation."

You know that there was once a problem that caused the wire to heat up enough to melt the insulation.

The first thing to do would be to run the car with everything turned on and see if that wire gets hot.
If it does, then try each accessory individually until you find the culprit.

If it doesn't (which is likely), then you've got some work to do.
You need to follow the wiring harnesses and see where the melting STOPS, because you know that the short is at that point. That potentially includes the INSIDE of the harnesses, especially under the dash.
Melting like this is usually due to a short to ground, and should be in a circuit that is not fused (or is before a fuse) and in a fairly large wire, because a smaller one should not have been able to heat the main wire up that much. Use the diagrams in the Chassis Service Manual to narrow down the suspects.

You should either find a patch of bare wire with a nearby area that it could rub on and short out, or a repaired area where that used to happen.

Once you do, you should tape up or replace all of the melted wire(s) so that you can't get any more shorts. You might also consider calculating the maximum load on the main wire that's melted and putting in a fuse or fusible link a bit larger than that to protect against future mishaps.

- Eric

 

You might want to unwrap the harness. The wire was probably the wire from the alternator to the junction block. I would be willing to bet that the wire is clipped at both ends and a new wire was installed.

 

Thanks, guys! I'll start on it when I get home today.

 

Okay, I traced down the wire with the melted insulation. The PO had installed a pretty new one-wire alternator. And the melted insulation is from where he spliced the new alternator into the wiring harness to the junction block. Looks like I have a little re-wiring to do.