Generator Short?

T

Tails

New member
Hi there,

My father recently passed on his '30 Roadster to me. It's been sitting for the past 25 years, and thanks to all the help in this forum I'm on my way to getting it running again. =)

Yesterday I installed a fresh Optima battery, and after connecting it I immediately noticed there was a short. After tracing through, I've isolated the problem to either the cut out, or the generator itself.

One thing I've noticed is that there is almost no resistance between the terminal bolt and the body. It's showing 1.4 Ohms.

ynuJelN.jpg


Is that normal?

... Now I haven't fully eliminated the cut out from the equation either. The mechanism looks ok, but after removing it it struck me that perhaps the bolt connecting the lead from the junction box was too long, shorting against the outside body of the generator.

There's no continuity between the battery side and the terminal side of the cut off, unless I close the armature of course. So I _think_ that it's ok.

I tried searching through the forums but couldn't find a thread like this. I'd appreciate any help or advise you guys can offer.

Thanks so much,

Bonus picture of the cut-off, showing no connectivity while the armature is up:

1zTAHzF.jpg
 
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Low resistance on the output stud is fine. That cutout is a low quality repro, so I'd check the generator output with it removed. First polarized the generator to see if it works by jumping the output stud to battery voltage, which is the wire connected to the cutout output terminal. You can start the engine and let it idle, then see what the voltage is. At 500 RPM the generator should have about 7 volts. If you rev the engine without it being connected to the battery, the voltage can rise to 40 volts and burn out the generator rather quickly.

I see a part of the insulator is broken on the cutout, and if the cover hits the terminal, this will short the output to ground.
 
Thanks Tom, I'm waiting for a few parts to arrive before the engine is running again (notably a new head gasket). Hopefully I'm able to test the generator in a few weeks time.

I hadn't considered the cut off cover might have been the culprit, thanks for mentioning that... I'll go ahead and pick up a new cut off and eliminate it from my list of worries.

I'll post an update if I can get her sorted. =) Thanks again!
 
Bert's in Denver sells restored original cutouts. They are by far the best quality cutouts to use.
Bert's 800-321-1931
 
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