VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Generator or Voltage Regulator Problem???

38 Coupe with 6 volt stock system. The last couple of weeks the charging system worked well after cold start but if I shut it off and then restarted it took several minutes before the system started charging again. Today I started the car for the first time and there was no charge at all. I pulled the cover of the regulator and theres no action at all regardless of engine speed. Even momentarily closing the cutout relay manually had no effect. How do I test to determine if it's the generator at fault or the voltage regulator? I have a multi-meter but I'm no electrical genious. Thanks.

A quick test, remove the fan belt, use a piece of heavy wire to go from the battery terminal to the generator. Touch the wire to the generator and it should "motor". It should turn as if it were an electric motor. If it does not, generator is guilty. If it does motor, then take a look at the voltage regulator.

If it dont "motor" bundle it in a box to the Junkyard Dog. He knows how to fix it.
Tony

In some cases a generator will "motor" but still not charge. To determine if it is a generator or a voltage regulator problem do the following:

Remove the wire from the "F" or "FLD" terminal of the voltage regulator and connect the wire to ground. Increase engine speed. If the ammeter shows a charge then the problem is in the voltage regulator. If the ammeter shows no charge then the problem is in the generator.

Good luck!

Could a bad contact at the Ground (on Trans.) be part of the problem?

That's the kind of check I was looking for. Unfortunately I didn't read it in time. I hooked the generator to the battery wire from the regulator and it spun but not very fast. I pulled the generator and took it to the fellow that rebuilt it. He put it on his tester and spun it up. It showed 11 volts BUT he said he'd been having trouble with his tester and wouldn't bet his life on the results. I just happened to have an old Delco-Remy regulator that was given to me some time back so I pulled the new regulator that was in question and put the D-R regulator on after cleaning the points. The cut-out was set a little high, the engine had to hit about 3000 rpm before it kicked in. I adjusted the cut-out and the old D-R regulator works just fine. It charges 8 volts at highway speed. Looks like it's time for a little warranty action on the "new" regulator that cost me $70. :rolleyes: Thanks again for the help guys!

A little follow-up. I'm not so sure now it's the regulator. When I took the coupe out for a spin yesterday I still had some problems.

This morning I pulled the Field wire from the regulator and grounded it under a mounting screw. I got in the car and started it. After letting the oil flow for a bit I ran the speed up to about highway speed and the ammeter never moved off of just above full discharge.

I turned off the key, reattached the Field wire & pulled the regulator cover. I checked the voltage at the Battery terminal with everything off & it showed 6.10 volts. I started the car and using the idle screw ran the engine up to about highway speed. I showed about 5.9 volts then. The regulator cut-out relay was not engaged, I'm assuming because of the lack of voltage. When I manually pushed the cut-out relay to the closed position the generator started to charge and ended up charging at a 7.5 volt level.

I assume the way it's supposed to work is as the engine speed increases, the generator output increases. The voltage at the Battery terminal of the regulator increases which causes the cut-out relay to close, allowing current to flow through the regulator.

If I'm correct that all makes sense and the lack of voltage at the Battery terminal would indicate the generator is bad. What confuses me is IF the generator is bad, why does it start charging OK if the cut-out relay is closed manually? IF the generator is OK as indicated by it's ability to charge once the cut-out relay is closed, why is there a lack of voltage at the Battery terminal UNTIL the cut-out is closed manually? Electricity makes my head hurt!!! :confused: :confused: :confused:

Maybe you should read the shop manual again to see just how the cut-out is supposed to operate, is it supposed to cut-in in to start the generator to charge the battery then to cut-out to keep the generator from chargeing too much? maybe the cut out is bad? I wouldn't think the generator is bad if it charges the battery when the cutout is cut in. Things don't always work like we think they do, I reckon.

When you replaced the voltage regulator did you re-polarize the generator?

It turned out to be the generator. I took it back to the fellow that rebuilt it in the first place. He advised the commutator/ (the copper part the brushes contact) showed arcing and was dirty like the brushes were floating instead of making good contact. He cleaned the commutator, put new springs on the brushes and a new bushing in the pully end and it's as good as new. Life is good again.

Tiny: Great to hear that your generator is working again as it should. Good going!

By the way, checking the brush springs and replacing same as needed; and replacing the end frame bearing is always normal procedure when rebuilding a generator.