The Stovebolt Site Forums The Shop Area Engine Shop Alternator Not Charging on Chevy 235

Need some advice, my alternator was working fine charging at 14v or higher. I put a bracket on wrong and it started hitting the alternator fan. So, I fixed it immediately after I realized what I did. Then hooked the alternator back up, and now it will not charge. I put the multimeter on it and now it is reading 11v and no more. So, I took the alternator, and had it tested and two auto parts to see if that was the problem. Both auto parts came back that the alternator was fine. I also put on an old alternator I had laying around with the same result. I checked the fuses, and they have continuity on both sides. I recently put in a new wiring harness so there is no corrosion. What could the issue be?

If the alternator truly is fine, it has to be a problem with the wiring connected to the alternator. Does this alternator have an external voltage regulator? If so, check that.

no, it is internal.

We probably need to know what kind of vehicle you're working on, and whether the electrical system is original to the vehicle or some type of conversion.

Jerry

Do you have a separate ground wire for the alternator or are you just relying on it being grounded through the mount to the engine?

Especially if the bracket has been powder coated or painted.

Regardless of issue, and it might go without saying but I think I'd run the battery charger for a bit if only 11 volts.
Otherwise I'm over here in the cheap seats watching to see the solution...........

Mike Bell With your alternator turning at fairly high rpm see if that bearing opposite the pully is magnetic,if it is alt is primed. Could run a wire to the battery thru an ammeter watch out making sparks near the battery,can blow. Be sure ground is connected. Fuses that have been blasted can get a coating on the inside that will show a circuit to your ohm meter.

Chevy 3100 1950, it has a updated 12v wiring harness.

I have several grounds on the engine, cab, and frame, but not one right on the alternator.

Mike,

Perhaps you can provide a couple of pictures of your alternator and bracket set up?

There may be something we could see that might lead to further help on the problem.

Dan

I figured it out, it was a ground issue. The bracket had been powder coated, I added a ground wire to the alternator and it began working again, thanks.

Mike,

Thanks for coming back and sharing the solution you found.

Guess that means ascwranger1 gets the best helper award as he nailed the problem! Gord also earns one for having the base problem ID'd!

Enjoy the weekend all!

Dan

Mike Bell Great !! I like to hear that special noise a Delcotron makes when it is happy to be working.I have a regulator testor I made so you can shuck em in and out easily. My neighbor tested a 5 gallon bucket of regulators so we're stocked !!

Just for information,my alternator teacher would test the triode by seeing if all 3 circuits would light an ordinary 4 lamp system low beam headlamp,done a lot of them that way.