The Stovebolt Site Forums The Shop Area The Electrical Bay Truck keeps blowing up generators

Hi everyone, I've got a 1959 3100 Truck, and it's overall been running pretty well since I got it going almost a year ago. Except recently on a drive, my temp gauge and ammeter both started moving up and down with the engine speed, and pegging out around 30mph. A few minutes down the road, I smeld a hard burning smell, but it kept driving fine after that, though I did find the battery had started leaking after the event. I discovered later that the voltage regulator and the generator were both burned up, though I didn't know which had gone first. I replaced the regulator, and had the generator rebuilt with a brand new armature. When I put it all back together and wired it back the same way, I drove it down the road and it did the same thing within a half hour, right down to the burning smell. I haven't had a chance to check the regulator yet, but I've got zero volts from the generator at idle, so I'm assuming it's just blown up a second time. I've got a different battery on it than the one I had spilled over as well. I'm out of ideas here and a bit out of money to figure it out. Does it sound like they just missed something rebuilding the generator? Or could there be something downstream from the regulator that's caused it all to blow?

I forgot to mention that this time, when the ammeter pegged out I went ahead and disconnected the generator wires so that it would not blow up my battery again or ruin anything else. It was about ten minutes later that I smelled the burning, so I know for a fact it was the generator burning this time, and as it smelled the same, I'd wager that's what was burning last time too.

Sounds like you have an intermittent dead short to ground somewhere in the hot side of the charging system, or maybe a complete loss of ground for the system and it was overcharging the battery and feeding high voltage and amps through the wiring searching for a ground.

Possible. I could see that causing the pegging, but why would the generator burn up after it was disconnected from everything?

Was the regulator adjusted properly when the new generator was installed? There are three very critical regulator adjustments that must be made anytime any component of the charging system is changed. Closing voltage, current regulation, and voltage regulation. If your alleged "rebuilder" didn't insist on matching the generator to the regulator during the repair process, you need to RUN- - - -not walk to a different shop!
Jerry

Ah, well that wouldn't explain the first burn up, but possibly the second. All I did after putting the generator in was polarize the regulator. Didn't know anything about those adjustments, and I don't remember reading about them in the setup instructions either. It's also been brought up that my belt might have been on too tight, but I'm not sure about that. It did spin after all, and it failed awfully quick

I think your field wire between the regulator and the gen. may be shorted to ground causing full field at the gen. Or the regulator is not grounded which causes infinite charging.
The reg. is mounted on "rubber nuts". It must have a ground wire hooked to the base. Preferred going directly to the gen. ground screw.
There is usually a small hole in the base of the reg for a metal screw to attach the ground wire to with a star washer.

George

Let's communicate by PM, and possibly by phone. I can walk you through some basic diagnostic procedures and adjustments that might avoid any further problems. I spent 30-something years teaching auto mechanics, and doing a lot of automotive electrical work since the late 1950s.
Jerry