Smoking Alternator

Aloha from Hawaii,
This is a great site I just found it and hope someone can offer some advice.My 1986 CUCV started the other day like it always does and the alternator on passenger side started smoking badly.I disconnected the batterys and took it apart to see that it was fried.Got a rebuilt one from a shop third one that I have gotten from him and installed it when Istarted to hook up the baterries it was like fourth of july.I tried to trace the wires for a short but have not had any luck.If someone has any suggetions I would really appeciate it .
Thank You
Realtired

Search this site. There is a post that has a wiring diagram that should help you. As I recall, they run two alternators to charge two batteries to get thier 24V. Not the greatest idea in my book.. but it works.. sort of. Just double check your hook ups and make sure that if thier is a diode or two to keep things in check, that they are not blown causing back feed.
Personally... I would ditch the dancing alternators and just run one 24V. If I remember correctly.. you can just change your 12V regulator to a 24V and there you go. Good luck, and Aloha!

The alternator must have an isolated ground for the standard CUCV elecrical system. Sounds like your latest may not. Make sure your guy knows that you need an isolated ground. The ground of the passenger alternator is hooked to the positive 12V side of the fornt battery/left alternator.

Aloha Guys,
I had both alternators checked and they were okay and both have isolated grounds.Is it possible that the glow plug system or ignition switch could be the cause.
Thank you
David

Re: RE: Smoking Alternator

Bigmillman said:

Search this site. There is a post that has a wiring diagram that should help you. As I recall, they run two alternators to charge two batteries to get thier 24V. Not the greatest idea in my book.. but it works.. sort of. Just double check your hook ups and make sure that if thier is a diode or two to keep things in check, that they are not blown causing back feed.
Personally... I would ditch the dancing alternators and just run one 24V. If I remember correctly.. you can just change your 12V regulator to a 24V and there you go. Good luck, and Aloha!

Click to expand...

You cant do that on a cucv, they are wired different from the other m series trucks.
The entire truck with the exception of the starter runs on 12volts.

RE: Re: RE: Smoking Alternator

what wire were you attaching when the sparking started? a picture would be best.

I was connecting the wire that goes to the buss next to glow plug relay

why where you messing with a wire there for the alternators? i think you may have the battery cables on wrong, you should have a ground cable that runs to the front battery negative terminal. Then you have a long cable that has two battery ends on it, you attach the single end to the positive terminal on the front battery and the second goes to the negative terminal on the rear battery. (The wire that runs to the distribution block near the gp relay pulls from this to get 12volts) Finally you have a short red cable that gets connected to the rear positive terminal, thats where you get 24volts.

Went through truck today top to bottom left to right and could not find anything wrong finally took alternator from drivers side and switched with passenger side and every thing works great I tkink one of the alternators is not right but everything is working and I hate to fix something that is not broken.

only the passenger side alternator must have an isolated ground. that was the problem.

I am going to bump this thread because it's relevant.

Rebuilt GEN 1 today. When I gave it power, there was a pop, and then it started to smoke.

Killed power immediately (I have a battery cutoff switch which came in handy).

Now the cases are split again, and I don't see any obvious signs. Where should I begin?

I have all the wiring diagrams, have memorized and printed out the TM's and the Delco manual.

I know GEN 1 doesn't need to be isolated, so I'm not sure a fiber washer mess up would be a cause.

Any thoughts? Attached picture is the alternator in its current condition. I know the brushes aren't intact, but I did seat them and pulled the pin prior to installation. Also, the glow is from my flash, everything besides the reused hardware is shiny and new.

I'm stumped.

Both of those black wires look "funky" near the rectifier.

doghead said:

Both of those black wires look "funky" near the rectifier.

Click to expand...

There was some rubberized goopy stuff when I took it apart originally. I must have forgot a couple pieces.

I removed them and don't see any signs of shorts in that area, although the wire does look a little bulged.

Here's a close up of that wire.

This connection is broken. Any idea what function it serves? It comes from the Barrel type Capacitor.

Any clues as to why it would blow?

I once had the "magic smoke" leave an alternator when hooking battery cable back up after having alt apart..the rectifier blew.

Was it a bad part or an install issue?

Everything tested OK with the DMM.

Now my question is, do I replace the capacitor with the old one, or just omit it?
It is my understanding that it's sole purpose is to reduce radio noise.

MakersTeleMark said:

Now my question is, do I replace the capacitor with the old one, or just omit it?
It is my understanding that it's sole purpose is to reduce radio noise.

Click to expand...

You replace it. It is NOT there to reduce radio noise. It's an important part of the alternator.


I have some extras if you want one. Just pay shipping. I needed one to rebuild mine, and had to order some extras to make a minimum order. They are only a couple of bucks.

I ended up putting the old one in got it installed. All is good. Thanks for the reply and offer.

Edit to add: Be aware of this part from Alternator & Starter Parts Wholesale. It was brand new and showed no indication of tampering or failure.

Add a bit of PIT* to your life. But thankfully the 30 y/o one still worked perfectly.

It's nice to see dash lights and headlamps, and normally functioning wipers!

Long overdue, and it paid me back for it.