I tore the harness apart back to where the box on the fenderwell is and where the small wires for the grid heaters come out. The only damages are to the grounds and where the grounds melted into the other wires. It's such a mess I can't tell if they wore through into another wire to cause the problem or not.

Could the starter have shorted inside? The main cables got hot enough you can peel the insulation right off the positive cable.

 

Them little electrons look for the path of least resistance. If their normal route is restricted or missing, they look for another way out. They get angry when a bunch of them start fightin over who's gunna squeeze through that little wire first. So they melt the insulation to make more ways out.

 

I like that explanation!

Also a good reason to add grounds EVERYWHERE, especially on a Chrysler.

 

Two wiring items I've seen burn down wiring harnesses, or whole vehicles.
1. Missing grounds, usually left off by "mechanics". A light signal ground still in place then burns.
2. Unfused wire direct from battery to huge amplifier under a seat, all wiring and terminals exposed.

Classic was one I came across just driving around in California killing time. I came across a pony car along the freeway, hood up, smoke coming out. I stopped and found a young man standing there crying about losing his car, but doing nothing. A wire along the back of the engine was red hot and burning. I gave the battery terminals a twist, and the positive one came off. The wire started cooling off, but it and the harness it was taped to were burning pretty good. I asked if he had any water with him. Yes, he had a bottle of water. I sprinkled it on the fire and put it out. The wire, by the way went to the amplifier under the seat.

Without intervention the fool would have stood there and watched the car burn down, sorta like the Ford engineers did.

That reminds me, I need to obtain a decent fire extinguisher, external mount, and alarm switch for my ride.

 

You'd think they would know better right?

 

I had a bunch of grounds added, each one was redundant to both batteries. Everything is fused. No amps or fancy stereo systems.

 

Now that we've beaten you up a bunch, I read the OP and can get serious.

Yes, the starter can draw too much current. Usually it isn't a direct electrical short, but the bushings wear so the armature touches the field irons, and that magnetic short makes it draw much current.

A starter will also draw too much current if the voltage at the starter is too low. A bad engine ground or main cable can do that.

If your truck doesn't start before you can let go of the key, (bump) it's sick. Note that if the fuel is shut off, and it isn't freezing cold out, this starter spins the engine at a pretty good clip, faster than you'd think for a big high compression engine.

If the main wire got hot, and the large ground wire to the block did not, then all that current had to find it's way back to the battery through the body grounds, thus the carnage. A dirty or loose connection on that large engine ground will do just that. A failed crimp on a large wire is pretty hard to see, but shh.... it happens.

 

I dug up your original thread and re-read it :

https://www.dieseltruckresource.com/...n-t319355.html

Like I have already said many times, electrical situations are nigh impossible to diagnose from long-distance; that being said, from your description of events, I am going to speculate and say that your alternator has shorted inside and is what has caused your melt-down.

Many is the barn, tool-shed, and house that has burned on account of vehicles parked inside with shorted alternators.

Unlike your case, they usually wait to start the fire after everyone is home in bed.

Had your situation began immediately upon cranking the engine, I would go with jmartin's explanation of events; however, since it seems that the engine had been running for quite some time prior to evidence that anything was amiss and the fact that you state that the engine will still start after removing all the other GROUNDs, my first suspect is the alternator.


As for the engine refusing to shut-own, did you try the shut-down lever on the pump ??

 

I didn't try the lever, I was afraid of not being able to restart it til that old man showed up.

Once I got the ground wires ripped off the batteries, the smoke quit, and I knew I'd be able to find enough wire to get home if I didn't lose the starter cable.

Both battery cables were hot. Positive and negative. The two 12 gauge grounds to the alternator mount were OK and it did charge on the way home.

I'm thinking of pulling the alternator and having it bench tested. I did get it at NAPA. Or sending it and the old one to North Platte and having them gone through and converted to internal regulation.

 

The absolute best thing you can do for your alternator is to replace it with a 110-555 Leece-Neville.

 

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