Alternator Case Burning hot?! Need help

[Commander5993]

Hey Guys,

Over the past month or so, I've tried to go through the forums here to read up on as much stuff as I can. I've also been using the TM's and have all of them downloaded.

As per this problem, I haven't found anything in the TM's or the forum, related to this specific problem, if there's something in the TM's posting a pg # would be a great help. If there's a thread here on SS that may help, a link would be great also.

We have a 1986 M1008, it has low miles (12600) but was an electrical mess. Well, not as bad as some I have read about on here, but still needed a lot of going through. Electrical work isn't my strong suit to say the least, especially if it comes to using wiring diagrams. But most of the electrical work I have done is just simple end connector changes, repair broken wires, and other odds and ends.

The truck already had the 12v resistor bypass done before we got it, and the resister is MIA.

Here's what we've done so far:
We've replaced nearly all the electrical connectors by soldering on new terminals ends and using heat shrink in the following areas: From the battery cable ends and Terminals, All wires that connected to the 12v block on the firewall (replaced two pole block with heavier mil spec single pole block),
and all Terminals- pigtails- main power connectors = etc on both Alternators. As all of these connectors were either poorly done crimp connections, or just in poor condition due to age.

I have also replaced all GP terminals with the newer style wider terminals, along with a full set of new AC 60G GP's.

Also replaced the GP Controller Card with CUCV Electric Upgraded GP Card, and added in an emergency Manual GP Momentary Safety Toggle Switch.

Replaced the Under the dash relays (which go to the voltmeter and 2nd Gen Exciter relay?). Something interesting here was that instead of two relays, there was only one relay and one empty socket. So I took the one old relay out, and put in two new relays from CUCV Electric, filing both sockets.

Doghead Starter Relay Mod Upgrade.

That's all the electrical stuff that we've done that I can think of, might have to add something if I think of it later.

Ok, so that's some background on the truck up to date.

Now, here is the problem I've run into:

When I fired up the truck this evening after finishing the last of above electrical work, it ran fine. Dash lights came on and then went off as normal. No alternator lights showing after start-up, voltmeter is in the green. Everything looks good.

But after the truck was running maybe 5 minuets, we were looking at the Drivers side Alt belt, and thought it needed tightened up a bit. So I shut the truck off and proceeded to loosen the Alt adjustment, but as I was doing so, I put my hand on the Alternator casing, and it was surprisingly hot! Very hot, almost to the point it could burn. I felt of the passenger side alt, and it was almost cold to the touch.

I've looked at all the connectors on the Alt, everything is where it was before. I didn't change any of the wires around. I just replaced the end connectors and placed them back where they were.

So, after trying to look things through, we decided to get another Alternator, thinking it could have been an internal problem in the Alt itself.

As a side note here, I drove this truck back from Arizona just a few months ago, which was about 1700 miles. During that trip back, I did notice that the voltmeter would sometimes wonder into the yellow, but would usually return to green territory shortly. But I never thought to pop the hood and see if it was hot to the touch. So I don't know if it was doing that then or not. Never heard of an Alt getting hot like this before.

So after doing some more research here in the forums, I went down town to O'reilys and picked up a 01-0136 Alternator. (I think it supposed to be for a 75' Caddy Commercial?)

Installed the new Alt, fired up the truck, and had the same problem. It started to warm up pretty good only after 1-2 minuets of running, and the passenger side still fairly cold. Shut the truck back off before it got hotter.

So, I went and pulled the under the dash relay that was missing before. I believe that this relay goes to the alt 2 exciter?? At least that's what I read here somewhere.
Anyway, Started it up again, but problem persists.

Does anyone have any idea what the problem could be? Surely this isn't normal?

There are two wires which I have been unable to identify, nor can I find where they used to go. One is an orange wire which is going into the wiring harness just below the GP Relay. And the other is a black and white stripped wire going into the fuse box underneath the dash. Both wires have just been cut and were just sitting.

Could either one of these wire be the problem? Could they have anything to do with the back-up lights (as they are not working)
Any other guesses on what they are for?

I'm posting a couple pics below of the drivers side alternator and the two mystery wires.

Any help would be Most Appreciated!

Thanks in Advance!

 

[mudman]

Shorted Battery?

 

[cpf240]

My guess would be that the black / white wire under the dash is part of the seat belt buzzer circuit.

The orange wire next to the GP relay might be the GP controller voltage sense wire. There should be three wires connected to the side of the GP relay that goes to the GPs.

As for the alt getting hot, the only thing that comes to mind is an incorrect GP relay. Test the GP relay and make sure there is NO continuity between the small terminals and the relays mounting tabs. That relay MUST be an isolated ground unit. Using the wrong GP relay has been known to mess up the driver's side alt.

 

[Commander5993]

Shorted Battery?

Batteries all look good, no dash lights to indicate any problems. no problem starting the truck either, fires right up.

I was just reading on another thread, and if I understand correctly, there is a blue wire that goes to the 12v term block by the GP Relay, and that blue wire is the positive wire from the drivers alt?

I remember finding a blue wire that was broke (or maybe it burned into) and I extended it, and replaced the connector, and re-attached it to the 12v block. Could this have something to do with the problem?

I've got to be getting a back feed from somewhere or something, back into the alt. I just can't figure it out. It's gotta to be a wire somewhere in the wrong place, or something is not working correctly and causing a back feed...?

 

[Commander5993]

My guess would be that the black / white wire under the dash is part of the seat belt buzzer circuit.

The orange wire next to the GP relay might be the GP controller voltage sense wire. There should be three wires connected to the side of the GP relay that goes to the GPs.

As for the alt getting hot, the only thing that comes to mind is an incorrect GP relay. Test the GP relay and make sure there is NO continuity between the small terminals and the relays mounting tabs. That relay MUST be an isolated ground unit. Using the wrong GP relay has been known to mess up the driver's side alt.

Thanks for info, I'll take a closer look at the wires to the GP relay and see about the orange wire. I'll also test the relay too in the morning. It looks to be original, but who knows. I was going to replace it anyway with a new one from CUCV Electric, but haven't ordered it yet.

I'll post my results tomorrow.

I think you might be right about the black and white wire, as I do not hear any seat belt buzzer at all.

Thanks!!

 

[Commander5993]

That blue wire on the Glow Plug relay is a ground wire. Disconnect it and see what happens

Ok, Thanks! I'll try that tomorrow too and report back.

I know its got to be just a wire in the wrong place some where or something. Hopefully get this figured out tomorrow.

Thanks!

 

[Commander5993]

That blue wire on the Glow Plug relay is a ground wire. Disconnect it and see what happens

Ok, Thanks! I'll try that tomorrow too and report back.

I know its got to be just a wire in the wrong place some where or something. Hopefully get this figured out tomorrow.

Thanks!

Speaking of the blue ground wire to the GP relay, that's the ground wire that goes to the GP Card, right? I hope I didn't mess something up when I spliced in the manual GP momentary switch....
It seemed pretty simple, and I read several posts about it. I just wanted to have the manual switch for the "just in case" back up.

 

[M1008driver]

FYI- There are two blue wires. I think it is the second wire, which is light blue, next to the purple wire on the end. I think that is right. It's been awhile for me.

If you spliced that way it is not your problem and must be something else.

http://www.steelsoldiers.com/cucv/59375-manual-glow-plug-install.html

I added two pics for ideas; gp relay and gp resistor bypass. Disregard the orange and black wire at the top as it is my trailer brakes.

EDIT-

One is an orange wire which is going into the wiring harness just below the GP Relay.

I am no expert, yet, but each alternator has a wire from the harness to the 12 volt junction. I would research more before just taking my word and connecting the wire. Just trying to give you ideas.

 

[Commander5993]

FYI- There are two blue wires. I think it is the second wire, which is light blue, next to the purple wire on the end. I think that is right. It's been awhile for me.

If you spliced that way it is not your problem and must be something else.

http://www.steelsoldiers.com/cucv/59375-manual-glow-plug-install.html

Correct, the Light Blue wire, which is the 2nd from the right, and is next to the purple wire. That light blue wire is the wire that I spliced into and my lead to the momentary switch, and then from the other side of the switch to ground.
And the link you posted is one of the more helpful manual GP switch threads that I have read too.

Thanks for confirming that this was correct!
I'll sleep better tonight knowing that I didn't just fry a brand new $80 set of AC GP's

 

[Commander5993]

Ok, I just went out and tested the GP relay as cpf240 instructed.

Using a voltmeter and touching the small terminal (which has the light blue wire connected to it,) and then taking the other lead and touching the mounting tab, I'm getting continuity. (arrows showing test points in photo below)
I tried this with the other small terminal as well, but didn't get any continuity from it.

This means the GP Relay is bad or incorrect, right?

If so, I'm going to search and see if I can find out if a civy replacement can be bought locally until I get one from CUCV Electric.

Thanks

 

[Commander5993]

Ok, well, I guess I'm going to go to NAPA and get an ST85 Relay for $64, as no one else in town has any others in stock. Hope this works.

 

[Commander5993]

Ok, removed the old GP Relay and tried to re-test off truck, and now I get no continuity between the small posts (either one) and the relay casing.

So I tested the light blue wire on the truck that connects to one of the small relay posts. And again I get no continuity between the light blue wire and ground.

So we're back to square one...

 

[Commander5993]

I don't what my next move is here. I have everything connected back to the way it was when I drove this thing home:

Right now the red wire w/white stripe (which is the input wire for the pass alt) which is also the wire that had burned the fusible link into, and that fusible link connected to the 12v block on the firewall, is now once again disconnected. The gen 2 relay under the dash has been removed. This is how is was connected (or rather un-connected) while I was driving home from Arizona, although I didn't find these problems until the last couple of days.

I have also removed the light blue ground wire from the small terminal on the GP relay, as was suggested by Warthog.

All of this to no avail, every time I fire up the truck, with-in 3-5 minuets, the drivers side alternator outside case is heating up.

How warm (if at all) should the casing be normally? I just don't see it getting so hot, while idling. This can't be "normal". Has anyone ran their truck for 5 minuets and then felt of the drivers side alternator case while running? Sure wouldn't be something I would do often, or would have done at all if I wasn't going to adjust the belt yesterday.

The passenger side alternator (even before I unhooked the input wire) has always been pretty much cool to the touch.

Oh, and by the way, there is no idiot lights on while truck is running, and the voltage gauge goes back into the green.

Anyone have any suggestions on what I should do or test next?

I'm going to do some more reading, but so far not coming up with anything useful to this problem.

 

[Commander5993]

Ok, I just made up my own test here. Not sure if this means anything or not.

I un-hooked All of the wires to the drivers side alternator. Started up the truck, ran for several minuets. The alt did not heat up at all, which was the expected result.

So we decided to hook up one wire at a time and see which wire, when connected, would cause the alt case to begin to heat up.

The first wire I connected was the two prong white "blade" plug that goes to the internal voltage regulator I believe. When I started up the truck, after about 3 minuets the alternator began to heat up.

So I assume the truck is calling for voltage, and the alternator then "engages" and begins to create power.

So again is this normal for the alternator to heat up this hot??

If someone can go out and start their CUCV and run it for say 5-10 minuets and report how hot their drivers side alt got, it would be much appreciated. It would at least give me a baseline to go by for what is "normal" heat output.

We tested the batteries and both are near 12.5 volts with truck off. Putting them on a charger to top them off anyway.

Oh and just in case someone is wondering, this truck is still 24 volt. Or at least the batteries are still wired into the 24 volt series.

 

[FireFighterHill]

Have you thought of taking out the alternator and having it tested at an alternator repair shop?

 

[Commander5993]

Have you thought of taking out the alternator and having it tested at an alternator repair shop?

That was our first guess, that it was an internal problem. But we just replaced the original drivers side CUCV alternator with a new one from oreilys yesterday. The original and now the replacement, are doing the exact same thing.

 

[Ken_86gt]

It may be normal or a bad battery, just trying to charging up the battery? Put a clamp on amp meter on the wires to see where the current is going. If you see 80 amps from the alternator and 80 amps on the battery then thats all it is. You could also check the rest of the wires- you should be able to figure out where the current is going quite quickly.

 

[Commander5993]

Although I'm not electrician, and have a hard time reading electrical diagrams most of the time. I'm usually ok with DC systems. I added a 12v system to our deuce, along with an entire accessory panel inside the truck. Usually I can trace down problems to at least the problematic part, and can either replace the part or repair a wire.
But this one has me stumped completely.

Going back to the TM's to see if I can find anything that could cause this, and to try to figure out if all the wires to the passenger side alt are correctly hooked up now, since several were burned. Guess this CUCV is equal to (or in worse electrical condition) like most of others I've read about.

 

[Commander5993]

It may be normal or a bad battery, just trying to charging up the battery? Put a clamp on amp meter on the wires to see where the current is going. If you see 80 amps from the alternator and 80 amps on the battery then thats all it is. You could also check the rest of the wires- you should be able to figure out where the current is going quite quickly.

My Dad and I were just discussing this possibility a few minuets ago.

So if a battery is low, and the truck is calling for voltage for an extended period of time (more than the normal cycle) the alternator would heat up to this degree?

Wouldn't the passenger side alternator also heat up as well though?

Thanks for the input!

 

[Ken_86gt]

Maybe...if you have a bad cell in one of the batteries. You could also take them to an auto parts store for a load test. The alternator would get hot if it is putting out a lot of current - this happens when there is an electrical load. It could be batteries, glow plugs, something else, maybe even some wiring issues seeing all the trouble you have been having. But if you follow the current with a meter you should be able to find your problem.

It is normal for the alternator to get hot when the battery needs charging. If the the alternator is only putting out a few amps after startup then the alternator may not be getting as hot as you think it is.