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I have been having a number of charging issues with my 66 c10 over the past couple of weeks. Rather than go in all the detail, let me tell you where I am as of right now.

I have an alternator with an external voltage regulator. I replaced the alternator about two weeks ago, and the voltage regulator last week. Since then, I have noticed a whining (buzzing) noise in conjunction with my generator light coming on. I first thought that the noise was coming from my alternator. This was not constant, just a few seconds per occurrence. When it did occur, the battery meter in the truck would go up and down - all over the place.

As it turns out, the whining noise was coming from the voltage regulator. I have no idea what the cause is.

I have tested all connections and grounds. All checked out. I even added a ground from the negative battery terminal to the body of the voltage regulator. Still no change. I bypassed the voltage regulator and confirmed that the alternator is pushing 17 volts, and the battery reads 17 volts when unregulated.

I replaced the voltage regulator again. The one that I took off had signs of heat on the back side. Put the new one on. Start up the truck and the volt meter shows 14 volts at the battery. No generator light; no noise. Turn it off, and then back on. Generator light comes on for a few seconds. At the same time, the regulator whines, and the volt meter drops to 12.5. Then, on its own, the generator light goes off, whining stops, and volt meter goes back up to 14.

I continue to be at a loss, and do not know if I should be concerned, or just leave it alone as the battery is charging.

Take your alternator back to the store and have them test it. It may be passing ac. Other thing is air gap on regulator. It might be to wide.
HotrodLincoln will be by shortly to straighten it out. Good luck.

When you take it back, maybe get a one wire Alternator that doesnt require an external regulator?

I took the alternator back last weekend and had it tested again. It checked out fine. I am hoping to make things work with what I have as I have a lifetime warranty on the alternator and the regulator. I am thinking about going to a solid state regulator - but I don't know if that is going to fix the problem.

Should I be worried about what it is doing right now?

"Worried" is a broad term. I used to read the side of the bias ply tires to see how many plies it had so I knew when I was down to the last two so I would know when to start shopping for some "new" used tires. (Running down to the very last ply would have been reckless.) I am not recommending that particular method to anyone, but I used to be po (couldn't even afford the other "o" nor the "r").
Carl

I tried to get that much use out my tires, Carl, but that was back when VA had inspections every 6 months. They checked the tires.

This post is not about tires?

So wanna laugh? I thought Bias Ply meant TWO PLY. I can see Carl sitting in a chair next to the tire, waiting for it to tell him that he's down the the last (only) two. It speaks to you Carl! Just wait for it..

No Gilligan.. its about Alternators and what the poor guy is supposed to do. Its a whining noise! My suggestion is to turn off your internet connection and see if it still persists! LOL! But really, someone help the poor guy out!

http://www.sttc.com/resources/tire-info/ply-rating

My 1954 6.50x16 were 6 ply (supposedly always an even ply number for bias ply)

Yeah, I didn't know! Its funny how a person has holes in their knowledge that you could drive a truck through. I don't remember the days of bias ply very well.

Sear Allstate bias ply truck tires - I remember them well

So, anyone else ever encounter this issue with an external regulator and have any ideas what the cause may be?

Sounds to me like an issue upon startup and the RPM's settle in that the regulator isn't breaking over into regulation for a brief period. This could also be linked back to the alternator. Until it reaches the needed RPM to satisfy all of the rectifying diodes and put out enough stable voltage and current the regulator can't settle in. The whine noise is usually the sound of AC voltage coming from the alternator I believe. The diodes in the alternator are what converts the AC to DC. Very dirty DC since it's not filtered but DC none the less. You may be perfectly fine if it's just a momentary thing on startup. Just sounds to me like it takes a second or two for the trucks RPM's, the alternator, and the regulator to all come together and break over into regulation. Someone else might be along with deeper knowledge than me to point you better to eliminate the whine completely.

The remote regulator Delco charging systems were mediocre at best when they were new, and 50-something years of age hasn't made any improvements. The first thing to do is to get a factory wiring diagram and make absolutely sure the circuits from the alternator to the regulator and under-dash wiring is all intact and does not have any loose connections, corrosion, etc. No shortcuts here- - - -you've already tried the shotgun parts at it approach, which didn't help. The hum noise is probably coming from the field relay which is supposed to activate the alternator on startup. It's one of the two mechanical contacts inside the regulator cover.

There are solid state regultors available that eliminate the mechanical points and keep the appearance of the original equipment regulator. If you have some compelling reason not to retro-fit the system to the 10-SI internal regulated alternator, at least go to the electronic remote regulator. They're available on Ebay, and they're cheap! Be sure to wring out the wiring first!
Jerry

Thank you Hotrod Lincoln. I did verify the wiring on Sunday as I was testing grounds. That all checked out. I did find some exposed wiring at the ignition switch in my inspection. Nothing was loose or corroded. Everything was where it was supposed to be.

This is the second vr that I put on the truck since the problem surfaced. The first was way worse - battery wasn't charging, and voltage output was all over the place. This one is charging the battery. The hum is only for a few seconds on start-up. If it doesn't happen right away, then it happens when I first pump the gas. Again, it stops on it's own after a few seconds, and voltage steadies at about 14 volts.

There is some flickering in the lights, but that levels out as well.

I am picking up a duralast solid state regulator today to see if that changes anything.

Thanks for the feedback.

There is another thing you can do. If you are one of those that likes to keep everything stock for show purposes. Just get yourself a one wire alternator... Hot Rod Lincoln calls it a 10SI internal regulated alternator.. its commonly called a one wire alternator. No external regulator is required. By jumpering your external regulator box in such a way that it bypasses it completely, you can make it look exactly as stock, yet have the advantage of the simplicity of a one wire alternator.

There is no way I would install anything else in my vintage vehicle now that I see the advantage. One wire from the Alt to the Battery. Thats it! Of course on the outside of this one wire alt is two terminals. Jump the field wire over to the main lug so it keeps its charge, and its ONE and Done!