The Stovebolt Site Forums The Shop Area The Electrical Bay Charging issues

I have a 51 3100 with what I think is a mid 60s engine and trans (casting numbers). When the switch was made, I assume the truck was converted to 12v at the same time. It's running an external regulator. About a year ago my gauge was showing random charging in 1v increments. Took it to autozone, tested, and it was the voltage regulator. No problems for a year. Recently the gauge is showing 11.5v. Replaced the alternator and no change. Checked voltage at alternator 11.5v. Bench tested alternator at parts store, tested good. Replaced voltage regulator, no change. Had truck tested at parts store, faulty regulator. Replaced regulator, no change.

So any thoughts? 2 bad regulators in a row?

I could swap for a 1 wire, but I'm invested with the setup now.

Thanks in advance

Ryan

Bad regulators not uncommon these days!

My father had a saying- - - -"Getting repair work at a service station is like getting brain surgery at a drug store!" In the same general train of thought, getting electrical diagnosis from some computer jockey at a parts store makes just as much sense. Find someone who can follow a wiring diagram and see if all the circuits are intact. Use a wiring diagram for a late-1960's or early 1970's GM vehicle with the "Delcotron" external-regulated alternator, and duplicate the circuits exactly.

Converting to an internal-regulated 10-SI alternator would be a far better choice.
Jerry

A 10 SI cost around $40.00 with core around here. To get a running truck for $40.00 ain't bad. BUT, as Jerry stated. Your problems very well my run deeper and a knowing 'set of eyes' would help. Reach out to that electrical guru down the block.

Thank you guys for the info. Always good stuff here. I think I'll go with a one wire. Going to see if the place I purchased the alternator will work with me on a swap. I really don't know anyone with the knowledge I need to fix the current setup, running a 3 wire with diode/light is more work than the one wire. I know there are pros and cons to 1 vs 3...

Thanks again.

Ryan

Take a look at Fifth Ave. Garage Randy Rundle is an alternator guru. He carries 6 and 12 volt and with his alternators you don't need to rev your engine to get them charging. Plus he's a great guy to deal with! Lots of great info on his site.
Steve

Parts store swapped me for a 1 wire straight across. Truck is charging at 14.68 at the alternator.

Hopefully this fixes it. Thanks again for all the info.

Ryan

Check the battery terminal voltage, not at the alternator. With good connections and the right gauge wire, you should see 14.5 or better against a fully charged battery, less if the battery is low.
Jerry

Can you put the old wide generator pulley on that 10SI?

There are pulleys available for tractors that run the wide belt. Check Ebay for "wide belt alternator pulley". It's a quick swap with an impact wrench- - - -no Woodruff key, just a friction fit.
Jerry