The Stovebolt Site Forums The Shop Area The Electrical Bay High Output Alternator putting out 16.68 volts

Hi Guys...

My 66 C30 Tow Truck has a high output alternator. Everyone always points it out when I have the hood open.

I just started to smell rotten eggs, so I tested the volts at the battery and it reads 16.68 volts. I am assuming the regulator has gone bad.

The problem is, I am not sure where either the alternator or regulator came from. I assumed they were an upgrade from the factory, but have been told it was added by the tow truck manufacturer.

The regulator is not stock, it is bigger, aluminum and has fins. Can anyone help point me in a direction of a fix? Do I need to know more about the alternator to find a compatible regulator? Can I use a stock regulator?

Right now I am going to try and unplug the alternator so I do not burn-up the new battery.

Thank you in advance for any help... Russ

If it's a Delco heavy duty model I have some factory tech bulletins on that system, I believe. Does the regulator have a big power transistor on the bottom of the aluminum heat sink? The mid-1960's White Freightliner I drove for a while had the same system, with a solid-state remote regulator.

Drop me an email or a PM.
Jerry

How many connector terminals does the regulator have? There were two varieties, one with 3 terminals and another with 4. I have testing and repair information on both types which I can scan and email. These regulators were designed to be repaired- - - -they're not throw-away units. It looks like there are two power transistors involved in the circuit, not one, as I had originally thought. It looks like you've got at least one transistor with a dead short supplying full voltage to the field circuit in the alternator.
Jerry

Hi Jerry...

Thank you for getting back to me.

I took the truck down to get a new exhaust put on... to avoid burning up the battery, I disconnected the plug at the regulator. It was a 4-wire in-line plug. In other words, the plug was long with each wire next to each other. I think that is stock.

I always assumed it was a Delco Heavy-Duty alternator and I thought it stated Delco on it, but I cannot verify that until I get the truck back tomorrow.

I really like the alternator because of all the comments and it does help with all the lights on the wrecker, so if I can repair the regulator, that would be great.

My email is [email protected].

...Russ

I'm out of town for the weekend, but as soon as i get home I'll scan and email some repair manual pages that cover the regulator I think you're dealing with. One variety has a round plug with a 3-wire connector, and the other has a 4-wire inline plug that resembles the one for a remote-regulator automotive setup. Both of them have a BIG cast aluminum heat sink and two big power transistors on ther bottom of the regulator.
Jerry

Does this regulator look like the one you have? Here's a brand new one on Ebay. "Make offer"!

http://www.ebay.com/itm/NOS-Delco-D...55917452?hash=item46420de48c&vxp=mtr

Here's the 3-terminal type:

http://www.ebay.com/itm/ESSEX-5-45-...33838065?hash=item4aad39faf1&vxp=mtr

Jerry

Hi Jerry...

I too was away this weekend... Yes, the first link with the 4 inline connections is the one. Thank you for the links. It made me take a good picture of the regulator because I could not really see it well. So I guess it is a stock regulator. This is good to know.

I will await your email with the scans.

Thanks again for your help!!
...Russ

I would grab that new one on Ebay, even if you happen to get your present one repaired- - - -that's a steal at the asking price, and it looks like they might accept a somewhat lower offer. A 40-year-old NOS part is worth having, especially one that's as scarce as that one!

I'm doing some macro digital pictures of the service manual pages- - - -they should reproduce better than scans.
Jerry