George;

Intermittents like this can sure make one crazy...having read your description of what happens twice, trying to understand it, I would think that it is more likely that alt output is being shorted (not the other way around, because a short in the alt drawing a bunch of bat current would indeed would fuse open the 8-10ga wire within about 10 seconds, and probably not go away afterwards...)...however a short within the solenoid as other poster suggested might cause this (shorts alt output, and also bat, so bat wire would get toasty too...)...in any case, I suggest putting a fusible link in line with the alt output wire to limit the current to something less than would fry the wire...also a temporary AMPmeter hooked up in a non-standard configuration in line with the alt would allow you to tell if it is a load on alt or within it!

Remember also that either the alt or the bat are supplying this power...for alt to supply power it must be turning...so does high load persist after engine is shut down?...bat can supply power any time, obviously...to put it in simplest terms: One end of melting wire must be supply, other end load...and the load drawing such heavy power is likely to be getting pretty toasty itself...so look for the hot device...

Keep a fire extinguisher handy just in case...

Good Hunting!

Have you tried the old "swap test"? That is, switch the alternator, vr, and/or battery one by one and see if the problem goes away? I figure you of pretty much anyone in the midwest/plains has a few spares lying around :)

Is there a ziener diode rectifier on that alt?
If so it could be damaged from the initial grounding,
and no longer regulating the output voltage.

Jorrell is an EE,but he hangs on the 200 board.
I can contact him off list and ask him if you wish.
--
69-145-S ; 71-145-S ; 72-145-E ; 72-1800-ES ; 87-245-DL

" This overload has happened on about 4 different occasions, as best I can tell not long after startup."

George,

I believe the Bendix is sticking in the engaged position. I am pretty sure that if you were to put your hand on the battery (+) cable immediately after this failure you would find it is hotter than a $2 pistol too. Potentially the starter and alternator have been severely weakened. Take all three to an old time auto electric shop for testing. Explain what you (I) suspect has happened. (That is if you still have one in town; they are getting scarce.)
--
Mr. Shannon DeWolfe -- (I've taken to using Mr. because my name tends to mislead folks on the WWW. I am a 51 year old fat man ;-) -- KD5QBL

Well, I'm sure I'm in way over my head and probably can't offer many useful ideas. But I'll take a stab. Myself, I'd suspect a problem with the alternator.

You sure the alternator can't put out that sort of power? Recall that you guys flipped out when I said that I had disconnected my battery when the car was running and my measured system voltage shot up to 16... You all told me that I had narrowly avoiding burning up all my wires... Maybe you've got a similar problem?

When the electric motor in my old portable tablesaw went out, it started pulling a lot of extra power and kept tripping the 15 amp breaker. Admittedly an electric motor is a different beast, but I think that the alternator can put out a lot more... ahem... err... current? voltage? amps? generally... "juice" (uh-oh here comes Ron Kwas to correct my usage of "juice"). If it is failing in some way?

My household wiring knowledge tells me that wire gauge is integral to proper amperage and too small a wire (say 14 gauge) is too small for a 20-30 circuit. Could the wire be burning up under too many amps? Maybe it's some problem with the battery as ballast?

Just a few cents...