Ford 641 B-Circuit Generator Charging Problem

I'm hoping Soundguy or other knowledgeable person regarding Ford tractor 6 volt positive systems can help me troubleshoot a problem I have with not getting the generator system charging sometimes on my 1958 Ford 641.

Sometimes the system will charge the battery and I can confirm that with voltage measured at the battery of 7.1-7.4 volts with the engine running. It will charge just fine for the entire time the tractor is running. I can go back the next day, start the engine, and measure voltage again at the battery and only get static battery voltage of 6.4 volts while the engine is running. So, the system is not charging again.

I have followed Soundguy's advice about polarizing a b-circuit generator by momentarily jumping bat to field at the VR terminals. I start the tractor and the static battery voltage does not change. I then use Soundguy's diagnostic check with alligator clip wires at the VR and with the tractor running jumper arm and bat (sometimes I get voltage to come up at this point but not always). I leave the first jumper in place and then I jumper bat to field and the voltage comes up at the battery. After this I remove the two wires with alligator clips and the voltage stays up at the battery and the system is charging. The system will sometimes maintain its charging ability over numerous engine start and stops over several days. However eventually, I'll start the engine and will only get static battery voltage. I have gone back through the diagnostic tests and at the end of the tests with the two alligator clip wires removed, the system is charging again.

Does this indicate I have a bad VR or other source of the inconsistent charging? Thanks for your help,

Jumped bat to arm and field effectively bypasses reg, if she charges like that. Gen is usually good, suspect reg

I will replace the voltage regulator and see how it goes. Thanks, Soundguy.

My guess you have a brush hanging up.

I went out to check the wire connections at the voltage regulator to see how much room I had to work and how I would tape and mark the wires before replacing the reg. I noticed the Fld wire connection was a little loose. I was able to tighten the hold down screw a quarter turn. I've started the engine twice since then and I'm measuring 7.3 volts at the battery, It's charging now and I'll watch it for a few days. Glad I didn't break the seal yet on the plastic bag holding the new reg. from TSC. Fingers are crossed....

Clean bright and tight like Dell says!

I experienced similar symptoms on my 1963 Ford 4000 charging system. In my case there was an intermittent short from the field terminal to ground.

Inside the generator there was a rubber grommet on the field terminal which had worn through and was allowing the terminal to make contact with the case.

This may not be your problem, but I wanted to share my experience with you, since my system would also charge for several starts and then quit charging.

Thanks, Mike, for the information about your experience. I'll keep checking how its charging.