Generator Issue on the '50 GMC

[rp2813]

Hey guys,

When I recently changed out the drive belt on the pick-up to the proper sized one and could still hear a slight noise coming from the generator, I read in the shop manual about oiling the it. Since this current generator has been on the truck for 30 years or more, I figured it could probably use some oil. I gave it a shot in both receptacles and let the truck run for a bit. The noise was still there, but I told myself that the oil was still distributing itself. That was probably a good three weeks ago, and since then the truck had been sitting. Yesterday I had to go pick up some pipe and fired up the truck, but the needle on the gauge didn't budge into the "charge" zone. If I turned on the lights, the needle would go the other direction slightly, so it's not the gauge at fault.

I'm making a direct connection between oiling the generator as the shop manual instructed, and the fact that it's not charging anymore. Is there a way to reverse what I've done, or do I need to run the h*ll out of the truck and try to get the oil worked out of wherever it ended up? The generator was charging fine before I messed with it, even though it was making a little bit of noise.

I'd appreciate any advice on how to deal with this. I'm not looking forward to pulling the generator and opening it up, but am thinking that might be the only option.

Ralph

 

[kenwashesmonday]

If you over oiled it, you may have oil on the brushes.

Ken D.

 

[58limited]

Do you have a good alternator/generator shop in your area? If it is 30 years old, I would have it serviced. There might be an internal problem and adding oil might be coincidental to the lack of charge.

 

[rp2813]

I'm thinking the oil-on-brushes issue may be it. I can pull the generator and take it to the nearby auto supply and they can bench test it but if I'm going to pull it, I'll check out the brushes myself first.

Considering this generator has been doing fine for the past 30 or so years, I'll never be bothering to oil it, or its replacement if that's what's necessary, again.

 

[qsd-dan]

On my '59 Pontiac, there is an oil port to oil the rear bearing. When I rebuilt the generator, the rear bearing was changed out to a sealed design. Luckily, I never oiled it as it would have accomplished nothing while at the same time making a huge internal mess. I wonder if your 30 year old generator had the bearing changed out to a sealed design? I'm almost willing to bet it was.

The rebuild kit I got for my generator furnished a sealed front and rear bearing, so I don't even think I could get the older style bearing even if I wanted to without locating an NOS one via Ebay.

When you re-install the generator, don't forget to polarize it or else it won't charge.

http://web.utk.edu/~tprather/FoothillsTractorClub/TechTips/PolarizeGenerator.html

 

[rp2813]

Dan, you may have nailed this one. I think I'm destined to pull the generator and clean it up. This latest dose of rain will need to stop and I'll have to clear some space on my work bench first.

Thanks for the link to polarizing. I had forgotten which two connections had to be jumped on the voltage regulator. I believe that since this system is positive ground, I have to do it backwards and I don't know if that means touching "field" first or "armature." Any tips would be appreciated.

 

[crevicetool]

That's what I was thinking.....

not polarized. Was the original noise mechanical in nature or was it a whining? A "whine" might indicate the regulator. 1950 was still a six-volt system right?

Rick

 

[rp2813]

Yeah, no whine on this thing. Just a little bit of a raspy sound that seemed to be coming from the generator. It's all too coincidental with the oiling, so the generator is where I'm going to look first.

 

[rp2813]

Oh yeah, it's 6-volt positive ground.

 

[sudsmaster]

Ralph,

You can check the brushes yourself on most of these generators. If they are worn down to the holders, that could be causing the rasping sound. I'd check them sooner than later as you don't want the worn brushes scoring the rotating part they ride upon (armature? rotor? it's been a while).

Also, if you have the armature turned at a repair shop, make sure either they chamfer the edges or you do it yourself. I didn't understand this bit when I had the rotor turned on my Plymouth generator, and it proceeded to eat brushes at an alarming rate (kind of like a vintage Cuisnart). Finally I replaced it with one I got off a spare vehicle and that one has run fine. One of these days I'll pull the rotor/armature again and chamfer the edges myself.

 

[rp2813]

I can't imagine the brushes being all that worn. This truck has had super light use for most of the time this particular generator has been on it. Should I need to pull it off the truck, I'll be having to deal with the brushes, so I'll find out then.

I'm 99% sure that over-oiling is the issue. Nowhere in the shop manual do they say how much to use, and a guy from another forum for old GMC's said it should only be a few drops. I definitely put more than that in there.

 

[sudsmaster]

As I recall, on my Plymouth, it was easy to check the brushes with the generator in the car. There's a metal band that can be removed (just s big screw clamp). And under it are the brush holders. I learned how to check them fairly quickly when I had the brush-eating generator installed.

 

[rp2813]

Yeah, there is a band around the commutator (?) and brush zone. This one snaps apart/into place. I'll have to check whether I can assess the brushes by removing it, although since it's too coincidental with the oiling and the charging issue, I really doubt the brushes are bad. The whole area could do with a good cleaning up, and with the nice weather that's supposed to be with us for a decent stretch, this may be just the time to tend to this. Plus, I don't want a dead battery at some point, so I need to resolve this.

 

[whirlaway]

Generator

Hi! Ive worked on many of my own old 6volt Desotos and Chryslers,that whine is 98percent brushes.Brushes actually fall apart more than they wear out,heat and vibration ages them badly.Also take a piece of emery cloth and polish the commutater before you install new ones.I would think just about any autoparts store or if you have a big truck shop close should have them.When I lived in Calif.My Desoto threw a winding in the armature and in those Chrysler Products your power steering was driven on the back of the generator.From 1951 to 1956.I took the car to A huge truck electric place in Anaheim,they were so kind rebuilt the generator and rewired all of the cloth wiring under the hood very cheaply. Bearings usually growl or shriek.You probably didnt over oil it,sounds like they were going before. Good Luck Bobby

 

[rp2813]

Well, I rigged an emery cloth block that I could use on the commutator while it was spinning. It didn't help. I polarized and that didn't help. So now I'm going to pull it. If it needs brushes, that sounds like a fairly easy thing to do. Never done it before, but if I can just buy the brushes, that's what I'll do. Once I have it apart, I'll also be able to see if oiling had anything to do with it. It does seem like a strange coincidence, but wouldn't be the first time for that.

 

[sudsmaster]

Cool, just make sure you take the old brushes with you to the vintage auto parts store to get new brushes...

Not sure how you were able to use emery on the commutator (thanks for mentioning the correct name) without pulling the brushes. No matter.

Oil itself might not upset the brushes, as it should be non-conductive. Maybe it helps to break them down? Don't know, never had any oil cause problems with brushes on the Plymouth.

Probably should add a few drops one of these days, come to think of it. And check the brushes while I'm at it.