smoke at fusible link

[gnick]

I noticed the voltmeter in my M1009 moving around a little bit lately when I give it throttle. the front battery tested 14.7 when running and the back battery tested 14.7 while running. However, when I gave them both throttle the rear battery would jump up to 15 -16. I had a rebuild kit handy from ASP wholesale so I decided to rebuild it. The rebuild went smooth, and I put the alternator back in the truck. When I was reconnecting the positive battery terminals i saw an arc somewhere on the alternator and smoke started to come from the fusible link next to the glow plug relay. I also saw some smoke from one of the bus's near the battery. I immediately disconnected the batteries and inspected the fusible link, and the blue wires had melted some of the insulation off. I pulled the alternator back apart and there is nothing jumping out as a problem in there aside from one of the screws that held the rectifier down was a little lose. It was the large philips head screw.

Any idea what happened here? Is there something I should check on that alternator. I hate when this happens - NOTHING WAS SUPPOSED TO GO WRONG!

update: i was looking at this thread http://www.steelsoldiers.com/showthread.php?146703-CUCV-Alternator-Rebuild

i think I'm missing the insulating sleeve for the rectifier mounting bolt. I'm going to pull it back apart and check. not sure where i could have gone, but it wasn't there when I put it back in. Could this be causing my problem?

 

[doghead]

Yes.

 

[MakersTeleMark]

I got a bad part from ASP and had the magic smoke when I rebuilt GEN1. Don't remember which part, but I will look for the post.

http://www.steelsoldiers.com/showthread.php?20953-Smoking-Alternator/page2

 

[gnick]

Thanks makers - everything inside looks in tact. The smoke didnt come from the alternator, it came from the fusible link and bus bar.

i took it all back apart, and insulated that screw. batterys hooked up fine. truck started up fine with no smoke anywhere, but the GEN 2 light stays on. I checked both terminals on the back of the alternator.

the lower one read 14.7, upper one read 27.1. However, I am not getting the same power to the rear battery. it is not charging.

any ideas? maybe i fried something in between the alt and the battery?

 

[Warthog]

You need to replace the fusible link behind the rear battery and the one by the glow plug relay.

There is a How-To for fusible links in the CUCV Helful Threads sticky

 

[gnick]

thanks warthog - I'm going to check them all out today.

 

[tim292stro]

...I think I'm missing the insulating sleeve for the rectifier mounting bolt. I'm going to pull it back apart and check. not sure where i could have gone, but it wasn't there when I put it back in. Could this be causing my problem?

Yes.

What ya did there by not having that insulated spacer was convert the isolated ground alternator into a non-isolated ground alternator. As soon as you hook that up you short out one of the batteries...

Fix this before you even think about starting to replace fusible links. You may have burned up the new regulator too...

 

[gnick]

haha yea, what a learning experience. so its all rebuilt with the insulators. No arcing or shorting out. I replaced all of the fusible links. Everything starts and runs fine, but the gen 2 light stays on.

I checked the alternator

Key off - exciter = 0v, Red wire on plug = 25v, red wire on large lug = 25v
truck on - exciter = 14.7v, red wire on large lug = 27v

rear battery is still not charging. One time i revved the truck up into higher RPM's and i saw the voltmeter jump like it normally would when gen 2 kicked on, but it went right back off.

I don't think its the regulator because that's what keeps the voltage at 14.7 - correct?

i might buy another rebuild kit, or maybe just get another 27si for the time being. This was my first shot at rebuilding an alternator - you live you learn.

 

[Hasdrubal]

I once had the magic smoke emanate from an alternator, shop told me it fried the rectifier.

 

[tim292stro]

If the exciter is not turning on the field the Gen2 light will not go out - if you rev the engine does the Gen2 light go dark?

Still sounds like you cooked the regulator for now...

 

[gnick]

no - when i rev the engine the gen2 light does not go out. I'll see if i can grab a regulator/diode trio from napa and swap it in today.

 

[tim292stro]

Gen1/Gen2 lights are controlled by the field power provided by the regulator. The positive side of the bulb is powered by the ignition for Gen1, and by relay controlled by the ignition (and hooked into the 24V's upper 12V battery positive) for the Gen2. The lamp is connected to the field coil in the rotor through the brushes - the other side of the field coil is connected to the negative side of the rectifier.

If the field coil is being powered by the voltage regulator, so if the regulator is in fact driving the field coil and making power, the GenN light will get two positive wires and will not light. If the regulator is not powering the field coil and making power, the GenN light will have the positive ignition supply and will be given a negative wire through the undriven field coil.

So if you are not seeing that light go out, your regulator is not driving the field coil, and you are not making power - your regulator is toast. I do agree on replacing the rectifiers as well - they are probably damaged if not killed, and would result in a rebuild sooner than you want after just doing a rebuild.

 

[gnick]

that makes a heck of a lot of sense. Thanks!

 

[gnick]

Hi Everyone,

I'm just following up as I'm still struggling with this problem. I rebuilt the alternator again with all new parts. When i turn the key to run I get a Gen 2 light, when I fire the truck up the light stays on. I got fed up with it and ordered a new alternator from Rare Electrical. Its a brand new delco/remy isolated ground unit specifically for the CUCV. I put it in the place of the GEN 2, turned the key to run and no Gen 2 light. Fire the truck up and it is not producing a charge to the rear battery. From there I swapped over the isolated ground until from the drivers side (this was charging the front batt perfectly) into the Gen 2 position. It is acting the same way as the new one from RE. No Gen 2 light, and not putting out a charge.<br><br>I've read every thread on here about charging and been all through the truck with my multimeter, but I cant seem to figure it out. Why would the rebuilt alternator show a Gen 2 light and not charge, and why would the other 2 alternators show no Gen 2 lights and not charge???i appreciate any help.

thanks

 

[tim292stro]

Sounds like a fusible link is missing somewhere - can't "brain" much more than that - work is melting mine...

 

[frank8003]

Post #2 ~ -..............

Yes.

That is a considered and thoughtful, all encompassing, straightforward, absolute answer.

That answer gets a cookie
Elvis last meal was four scoops of ice cream and six chocolate chip cookies.

 

[frank8003]

Gen1/Gen2 lights are controlled by the field power provided by the regulator. The positive side of the bulb is powered by the ignition for Gen1, and by relay controlled by the ignition (and hooked into the 24V's upper 12V battery positive) for the Gen2. The lamp is connected to the field coil in the rotor through the brushes - the other side of the field coil is connected to the negative side of the rectifier.

If the field coil is being powered by the voltage regulator, so if the regulator is in fact driving the field coil and making power, the GenN light will get two positive wires and will not light. If the regulator is not powering the field coil and making power, the GenN light will have the positive ignition supply and will be given a negative wire through the undriven field coil.

So if you are not seeing that light go out, your regulator is not driving the field coil, and you are not making power - your regulator is toast. I do agree on replacing the rectifiers as well - they are probably damaged if not killed, and would result in a rebuild sooner than you want after just doing a rebuild.

I am soooo glad my Deuce doesn't have any of this stuff!

 

[bigflew]

All I have to say is you better get used to smoke coming from under the hood of your cucv.

 

[tim292stro]

You know with the exception of the M1010 - the CUCV is a remarkably simple vehicle, both mechanically and electrically. You just have to remember that they are 30 years old now and prone to deferred maintenance that'll crop up in the middle of the least ideal timing. Only way to "prevent" this is to totally tear down the whole vehicle and rebuild it - I have "prevent" in quotes as there is always entropy, sometimes a new parts just has a defect that didn't get caught during manufacturing (such are the times we live in now).

If your grounds are clean, your wires, switches, and devices in good shape, batteries charged, lube changed frequently and full, coolant clean and treated - these trucks will basically go until they rust out (which is admittedly a design problem).

For an '80's GM vehicle these things do remarkably well with respect to aging.

 

[bigflew]

Agreed for an 30 year old truck they do great I love mine and use them as much or more than most, but the electrical system is the weak point . most of wich runs through One fuse!!!