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Drove the '64 F-100 200 miles today. Introduced it to the '56 F-250. The '64 ran great on the highway. Back in my home town I ran a couple errands, came back after dark with the lights on. Shutdown in my driveway and notice the red GEN light comes on with ignition in OFF. Put ignition to ON and the light went out. Messed around with the switch thinking it was not reaching true OFF. That's when I smelled burning electrics....
Popped the hood and the generator is sizzling. So is the regulator. Disconnected the battery as fast as possible. So...
I understand a bad voltage regulator will cause battery current to short back through the generator with the key off. This volt reg is new...the guy I bought the truck from 2 weeks ago rebuilt the motor and replaced it. I'm thinking if he wired it wrong I never would have made it 200 miles home.
I'm going to start tomorrow by popping the top off the voltage reg and see if it's fried. Not sure if the generator was ruined or not.
And ideas on what could have caused it other than a failed voltage regulator?
It's the cutout relay portion of the regulator at fault here. They (cutout points) can get a layer of skunge on them if they sit unused for a long time.
Generators don't charge at low RPM, so to prevent battery backfeed into the generator itself the relay (is supposed) to disconnect the generator completely at idle and on shutdown. You could try cleaning up the point surfaces on the cutout relay with a file. I never had any luck with that. If the cutout relay points stick, then the pole shoes (the field iirc) can get roasted. If you see dents on the top of a generator voltage regulator, this is why, one way to get them unstuck. Banging on the regulator.
What brand of regulator is installed? Like everything else these days, overseas replacements are not specifically too good. If you're going to run a generator, use only a quality old school back in the day regulator. NAPA has a rebuilt (generator) @ $45, it's probably not a bad plan to replace them after letting the magic smoke out. It's always good practice to couple a new generator along with with a new regulator. But not a cheapie. I bought an NOS Motorcraft for about $70 from that place down in Waxahachie and it works great. Electric motor shops used to be able to tweak the regulator to a specific generator, if there's an old school shop still open in your area that would be worth doing. The generators actually run a little hotter than an alternator, according to the manual:
Alternators certainly replaced generators for some very good reasons, can't argue with that. Kept the generator on the 64 just to learn how they worked. Obsolete tech interests me up to a point, it's rewarding to see how things used to be done and make them work as well as they are able, within their limitations.
It would be interesting to know what might be the leading cause(s) for cutout relay sticking. I agree it doesn't seem likely to make two hundred miles if there were major issues.
If the cutout relay sticks and there's no fast way to disconnect the battery, could you just start the truck and get the current going back in the correct direction?
At least that would stop the frying generator until a 1/2" wrench could be found to remove the battery cable...
Yes, the battery is fine. I couldn't see anything wrong inside the voltage regulator so I reinstalled it and the truck fired up, but my voltmeter on the dash was only at 12V. I seem to remember it was closer to 14V before the incident last night. Put a handheld voltmeter across the battery posts with the truck running and it was the same thing, just over 12V. Turned off the ignition and the cutout relay worked as it should, GEN light went out. I installed a battery cutoff switch just in case it happens again. (That should be a little faster than a 1/2" wrench...)
12V across the battery posts with the truck running seemed pretty puny, so I ran a few tests, but I'm still not sure.
First test: Run the generator like a motor.
Procedure:
1) Disconnected the field and output/armature wires off the generator (left the ground in place)
2) Put a jumper on the generator between the field post and the output/armature post.
3) Loosened the generator mount and slipped the belt off.
4) Ran a jump wire from the "+" post of the battery to the output/armature post on the generator.
5) Verified that it spun. It spun. Not fast, but it spun.
Second test: Run the generator without regulation and test output.
Procedure:
1) Reconnected the belt
2) Left the jumper wire on the generator between the field post and output/armature post. Left the field and output/armature wires that run to the voltage regulator disconnected.
3) Started the truck and checked voltage from that jumper wire to ground. It read over 25V.
Both those tests made me start to feel better, but then the last test was a head scratcher.
After hooking everything back up, I fired up the truck and tried out the new battery cutoff switch, expecting the truck to keep running with the battery out of the loop. It died immediately. I ran up the RPM's over 2,000 and again it died immediately. Tried it again by disconnecting the negative terminal, died again.
So any ideas? Does this sound like the generator is wounded but not quite dead? Any other test ideas?
Yep, you should be seeing 14.x volts say, headlights ON, at 2000 RPM. Batteries don't reach a full 100% charge till approx. 2 volts above the normal resting open circuit voltage. Then factor in temperature compensation. See chart above.
Just for grins you should try polarizing the generator. It's not "supposed" to be necessary unless generator has been disassembled or sat for a long time. Maybe motoring the generator accomplishes this? I dunno.
On Fords, with engine OFF disconnect FLD and BAT terminals at the regulator and briefly touch them together. May see a spark, that's fine.
That's a good point. Generators (and alternators for that matter) do not like high resistance. At all. And these old trucks have rust and corrosion in spades if they are original, and thick layers of paint if restored, in all the wrong places. Clean, shiny bright connections = Happy Electrons. Even a thin, nearly invisible layer of skunge is enough to interfere with the proper functioning of all kinds of things.
When I was young and didn't have any money, I always first tried to fix something that didn't work. A lot of times it turned out, not always but often enough, a poor electrical connection was the cause. Simply removing and reinstalling something was enough to get things going again! That simple fact has served me well over the years. People lose their troubleshooting edge when spending other people's money, I'm convinced ha ha
I did the polarizing trick this morning before all the other tests.
I'm thinking the generator cooked a little too much when the cutout relay stuck last night. It sort of works now, but probably not well enough. Why did it stick? No idea...the voltage reg looked perfect on the inside. Poor grounds could have easily played a role. I'll address that with the fix.
If the gen is fried it's probably time to cut bait and just switch to an alternator. Looks like the Delco 10si alternator with an integrated volt reg is cheap and effective Total package is under $50 with a core. I found a homemade Y-block bracket design online. Looks pretty simple....just a long 7/16 threaded rod, nuts, washers, and some 3/16" x 1" flat stock.
Speedy sells alternator brackets for the Y blocks for not too much money, if cosmetics are important.
Keep in mind if you do this though, that while any alternator available today will have far more current capability than a 30 amp generator, the trucks wiring harness itself does not. Maybe there is some overhead but I doubt it. So be careful not to exceed whatever was running clean as OEM.
Consider Ignition draws around 10 amps, the heater motor around 5, the lights all around probably around 12 or so. See where I'm goin' with that? Like I mentioned I was stubborn enough to make the obsolete tech work, learn the mysteries and rituals. It's rough out there these days - all the graybeards are about done and to most other people "generator" means a Yamaha. Thankfully there are sites like FTE and such. A Motors manual, the Ford Shop manuals are essential.
I have all the manuals, illustrations/text catalogs, etc for my '56. This '64 was supposed to be for utility only to move the '56 parts around!
I'm going to buy an ammeter today and do that test before I pull the gen. I'm also a bit nostalgic about holding onto old tech as long as it works. I wasn't going to go nuts with the replacement alternator...just a basic one with 50-60 amps capacity.
This diagram came up using a google search, but I'm puzzled a bit by how they show the battery charging circuit, coming off the B tab of the volt reg, through the light switch, through the GEN bulb (!), and then, finally, to the + side of the solenoid and the battery. So if the GEN light burns out, you stop charging the battery? That can't be right...
That's correct for certain charging systems not necessarily Ford, some folks will wire a small resistor in parallel across the bulb socket to preclude this. Thanks for posting the diagram, I'll have to study that for a while not that it will do much good, ha ha. It does appear that's the case, doesn't it?
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