Technical Generator Light Illuminated

Last night took the old girl on a mini road trip to a local park. Ran great but the generator light came on.. Tried polarizing the gen for grins, no joy there. Had another regulator in the glovebox but it was starting to get dark quick. Was about 15 miles away, cut the lights and limped in.

So today I swapped regulator and still not charging. Generator was professionally rebuilt about 1200-1500 miles ago, new brushes and bearings &c, regulator was NOS Motorcraft replaced same time.

All the wiring and ground checks out OK. So then I full field the generator and spool up the idle RPM to a couple large and nothing. The brushes are making contact, commutator looks OK. So I pull the generator. I don't know why Ford moved the Generator down low on the Y Blocks instead of on top of the engine as God intended. Anyway I still had the jumper wire from armature to field connected and hooked the voltmeter back up and spun it by hand on the bench. Showed about a volt. Hm... So then I spun the pulley with a drill and the generator is putting out 17 volts. So WTF is this all about? Not sure what to check next.

 

There are two generators, 30 and 35 amp.......they HAVE to matched to their proper regulator.

 

Hm. Good point but have checked the amp output sometime ago with an old Sun unit, as it's the only piece of equipment I own capable of measuring that high. It pegged exactly at 30 amps. Plus it's worked flawlessly for quite a while so I don't think that's it.

Checked out the wiring again a little closer the field wire at the generator connection has a break in the insulation a couple inches back, maybe it's corroded. It shows continuity (beep test) but maybe it's not able to supply enough juice? That's a WAG at this point. I think I can peel back some of the wrap and cut it back to clean wire and try that. I'm real particular about grounds and connections, everything is solid there.

 

Want to try motoring this Ford generator with a battery just for grins. Need the jumper wire connected from ARM to FLD to do this test correct??

 

Okay it motors up with a battery connected and puts out ~17 volts when spooled up. Have two regulators, the odds that both are bad is pretty slim. Guess that leaves the wiring but I can't figure what.

Brushes and comm. look good, cleaned up the wiring, resistance is in the ballpark between field and ground.

Installed generator. No charge. !! &@%#!

 

Put the generator back on and run a jumper from the gen to the regulator to check the wiring.

 

Yep, that sounds like a plan. Thought I'd also try a jumper cable from negative battery terminal to generator ground or case. Pretty sure the grounds are bulletproof though.

Jumper wires in parallel with the generator to regulator harness makes sense. They do show continuity though. Edit: Reading the archives here, Bruce Lancaster sez to disconnect at both ends whatever wire is being jumpered. Makes sense, might be grounded/shorted. Must be something really stupid I'm overlooking.

 

Field wire is open. Try byp***ing it and see what happens.

 

Tried that. No change. I measured 14+ at the ARM terminal of the regulator earlier at medium RPM. Should have checked at the solenoid to prove that section of yellow #10 wire.

So after I tried byp***ing the Field wire, I measured voltage at the ARM terminal again, and it was jumping all around on my meter. Same thing at the solenoid + battery terminal. Something is wonky in the wiring?

The generator is fine near as I can tell, and the likelihood of two regulators that worked fine before is pretty slim.

 

OK, using ****og voltmeter clipped to the armature terminal at the generator itself, common connected to negative battery terminal, I get 2 volts. A jumper between FLD and BAT terminals at regulator and it spools up to 15, 16 volts. "Full fielding" the generator. The only thing left to try is byp*** the #10 yellow armature wires to regulator and solenoid. I guess.

 

Ford.

Sent from my Z981 using The H.A.M.B. mobile app

 

Sounds like you have closed in on the problem. Armature wire to regulator sounds bad.

 

Please post the final fix.

 

Maybe.... Have discovered that I don't understand wiring and generator circuit near as well as I thought I did. I've been checking continuity of wires and finding it common to ground where I didn't think it would, and full battery voltage where I think it wouldn't. Thoroughly confused now ha ha.

The old girl has been real good over the years about not leaving me stranded, ever, and when something breaks it's close to home, it's uncanny. Have had other rides that are nothing but trouble. On a long roadtrip I'd have been really screwed.

 

For whatever reason the cutout relay is not being energized. Should have checked this first.

I can hold it closed and spool up the engine RPM a little and the voltage will hit 14 with + probe connected to ARM terminal at regulator and - probe at battery. Connected a jumper cable from battery negative to generator ground, and regulator body for another test.

One thing I thought to try is voltage drop test on the + side of the house to troubleshoot the wiring but not sure if the current might smoke my Triplett. Man I really **** with electricity!

 

Polarize the generator! Then see if the the cutout relay works.

 

Been there done that. Motoring the generator accomplishes this as well. Being a belt and suspenders guy though... Ford "B" type generators are polarized by removing both the FLD and BAT terminals from the regulator and touching them together momentarily. This is direct Gospel from the Shop Manual. Other methods (Delco) jumper wires etc may damage regulator.

So I pulled the generator again. Jumper from FLD to ARM, spool pulley with a drill and socket, and it produces ~12 volts connected to a voltmeter. When I tried this with it installed this morning I didn't get anything. Belt was tight.

 

Seems as if the generator is not able to charge with load. Try putting a brake light bulb from armature to ground on generator and fld to arm jumper and see if bulb lights correctly. Measure voltage across bulb too.
Is it possible you have a GM regulator and not a Ford?

 

OK, will try that here in a second. I have the generator re-reinstalled, again. Gettin' good at that ha ha.

I tried the Generator Output Test earlier but connected the ammeter wrong. The negative probe connects to the pos + terminal of the battery, not the negative. Doh!! Makes no sense to me, but they wrote the book. Here's the routine:

Jumper wire FLD to ARM, connect a suitable ammeter pos + probe to ARM terminal on generator, negative - probe to positive terminal on battery. Run engine to 1500 RPM. Should indicate 30 Amps.

 

Ok, the generator output test shows 30 to 35 Amps, "..generator should reach or exceed its rated output." This means the generator is not the issue here. I think....

 

Next test was "full fielding" type "B" (Ford) generator on the engine. Disconnect field wire from regulator. Negative voltmeter probe on negative battery terminal, positive probe connected to generator armature. Start engine. Momentarily connect field wire to BAT terminal on regulator. Voltage spools up to 14+ as throttle is goosed. So the generator seems to p*** every test that I can throw at it. Both regulators are 12 volt negative ground US made Ford or Ford type regulators. I replaced the old "repro" Ford Script regulator with NOS Motorcraft when I last replaced generator, it was working fine at the time. So while it's possible both regulators are defective it sure seems like a stretch.

 

Would brushes that are hanging up cause this? But, still p*** current (generator output)?? Will try some carb cleaner too on the commutator for grins.

Have read the brushes sometimes get stuck or hung up. Was planning on dis***embling the generator but got to looking closer at the brushes. Think they aren't making good, solid contact. Jamming on them with a screwdriver a little (tough when installed on the truck, could only get to one, and they looked like they were touching at least, plus have one of those rubber boots on there to try and keep crud out) on the bench and I believe they are now making better contact than before. The springs looked cheap I remember that. When I spin the pulley can hear them p*** over the segments now.

One thing I recall from a recent road trip, I would check the actual voltage now and then at 60 or 70 mph cruise with one of those handy digital voltmeters that plug in the cigar lighter receptacle. At one point on the homeward leg voltage started sagging quite a bit. No GEN light, but had to turn the headlights off to get back in the charge zone. Then it came back up. Forgot all about that till now. Could be wobble in the armature at high RPM (not me!) kicks the brushes out and they kind of stay out?

 

Sometimes after a rebuild, the pole shoes aren't seated perfectly and shift a bit. If they ever contact the armature, it will lose polarization. Happens with worn bearings also. But cranking a full battery 12v into the field still gives armature output.
With a B circuit, you should be able to just connect the Field wire to A and get full output by revving the engine. This test would rely on proper polarization and residual pole magnetism. If no output, I'd take the gen apart and look for scrub marks on the pole shoes and armature itself. The slightest contact there would kill any gen output.

 

You can tell if your brushes have not been making proper spring pressure contact by pulling them out an looking at the contact area. It will be burnt or browned along one edge or pitted. If it's ok, it will be pretty consistent and smooth looking.

 

Well I pulled the backing plate. One brush is worn a whole bunch and looks somewhat burnt along one edge, one is worn hardly at all. The worn brush, the spring wasn't doing anything at this point because of the wear. The brushes are long when new but they are not usable their whole length because of the spring design.

How long are brushes supposed to last anyway?! I drove this thing 20k with the other generator and never messed with 'em as I recall. These were new only maybe 2k miles ago. I dug around and found a generator rebuild kit that I forgot I bought. Bearings and brushes! Don't ya just love it when that happens.

There's a trick to installing the backing plate, pushing the brushes out of the way but I can't remember what it is. Jam something around them and pull them out once the plate is back on. Anyone know what I'm talking about?

 

Never mind, they snap right over the commutater. This one was trashed and at the end of its travel. A better spring would utilize more of the brush.

edit: Reading some of the old manuals, looked like a feller coulda made a nice cottage industry back in the day just rebuilding and servicing generators. Danged alternators! The commutators would get turned down, mica undercut, new bearings, and brushes. Pole shoes and field coils, growler tests, etc.

Looks like I'll need to sand the commutator to shiny bright and the brushes, to get a full contact patch. Make sure the brushes move smoothly in the holders, and the wires follow the brushes without hanging up. And then maybe motor the generator for a little while to kind of seat them. This may not fix the problem, but it needed attention.

 

Well I wondered about that. It produces full output, current wise. But that's with the battery in circuit in series. Can a generator p*** the current test and not be able to produce voltage? On the highway run I let it wind out a bit, for maintenance test purposes. A bent armature would have wobble and start maybe causing problems, I could see it kicking the brushes out.

Well it sure seems to p*** all the tests. I dug a little more and found some old Motors or reprints of something. There are some more checks I can do, but if a generator spools up voltage when connected as you mention - "to a high value" then the troubleshooting tree is clear "trouble is in regulator". It also sez to examine for burnt commutator or stuck brushes, so maybe I'm misinterpreting the results.

Never cored a generator, I have three of them laying around and about 35k put on this thing. Maybe one was an extra, I dunno. One has been dis***embled and the brushes are hardly worn, have to look at the other. Never gave the brushes a thought. For some reason these particular brushes wore badly. It was a "new" rebuild generator, with a 1995 date on it, bought last year or so. I recall the brushes did not make a good contact patch with the commutator. It was a little noisy for a while and made a hissing noise. Figured they'd wear in flat and be good for a long time. Oops! The manuals talk about using a long strip of emery paper and sanding new brushes into the commutator. Might take the generator and regulator(s) in to an auto shop that can supposedly handle this stuff if they don't have stupid prices. I'll ask him if they have a growler. If he don't know what that is, forget it. It's more fun to learn than give other people my money, sometimes anyway.

 

Going back over the tests you have already done, I would do the following:
Byp*** the battery + to battery terminal on the regulator. See if this does anything. Looking at the cutout relay circuit tells me that the relay relies on both voltage AND current to pull the relay in. If the battery is not connected (or high resistance) to the regulator, then there is little or no current at the cutout relay, therefore cutout relay does not respond. Your full field test with ammeter connected to battery and armature proves the generator out. BUT, there is another issue. If somehow the generator is losing it's residual magnetism, then it will not have an initial output, therefore no output voltage, and cutout relay does not respond. Somehow the armature output is not there without field being connected to 12 volts. See what voltage you get at the armature terminal at 1000rpm after starting engine. If nothing, then remove field wire at regulator and touch to battery terminal on regulator. With the field wire disconnected, then check armature for voltage. If residual magnetism is good, then it should have voltage at armature.
Also I would check all grounds related with regulator, generator, and battery to make sure they are good.

 

Is the cover on the regulator removable? Can you see if the points pull in or not?

 

That's what it "seems" like, too. The yeller wire has continuity from the regulator to the solenoid though. But, maybe it's unable to carry any actual current. Could try a voltage drop test, should not exceed a tenth or two. If it was the culprit, it would be dropping 10+ volts I think. I started to parallel this wire but then thought about the ignition switch wire, got confused and had to go lay down. I'll try hot wiring from regulator to solenoid.

Have done that, and so many other tests I'm starting to scramble my thinking. In the .mil we called you guys "spark chasers" LOL. Now I really know why! Jeeze Louise.

As I recall I was getting 1 or 2 volts at the armature and, after "flashing the field" at idle it would spool up to 14 volts, but don't quote me on that. One thing I didn't grok, I think the generator is in series with the battery, not parallel? So the generator voltage is added to the battery and then throttled back to 14 or thereabouts by the regulator?

Anyway thanks for the help and instruction. I'm going to dis***emble the generator completely and take a look at the pole shoes and the other innards and polish up the commutator and clean out the segments, blow out the brush dust and the rest of it, so it will be a day or two before I start in again.

One thing I'm discovering, an awful lot of "rebuilt" items for sale related to automotive don't have all the i's dotted and t's crossed. Carburetors for example. I did dis***emble it before installing the generator, maybe the brushes weren't seated right but they were square, no attempt had been made to seat the new brushes to the commutator I remember that. I "***umed" they would wear in quickly for a nice fit.