Alternator heating up

I have my old faithful 806 diesel with the alternator just started heating up. It's charging at 19 volts so the lights got bright and burned out.

I did some research on the forum here and found the bottom wire on the plug in at the back of the Delco alternator was the sensing wire for the battery voltage. When I checked the wire at the plug it has no voltage with a good battery and the switch on. The other wire is said to be the exciter wire so should it be showing voltage with the key on?

Would that make the alternator overcharge and heat up? I saw one diagram for installing one of these and he had come straight off the battery feed wire at the back of the alternator and ran that directly into the 2 wire plug.

Would that likely fix my problem?

Thanks a lot, as always, Bob

Sounds like either your battery is shot or the regulator in the alternator.

Well if the #2 sensing wire has no voltage on it then that could be the problem since the Voltage regulator will not see how well the battery is charged. The sensing wire is what tells the V.R. when to slow down charging and if it does not see battery voltage then it will make for an alternator to be hotter then it should. And yes the #2 wire can go right to the charge stud on the alternator since the charge stud wire runs right to the battery

I'll give that a try, then, thanks a bunch for the help.

Bob

The battery I have in is good and starts with no problem. I had a pair of 6 volts in it and they turned out bad. I now have a single 12 volt.

With the 6 volt jobs in it is when the over charge started. Then everything stopped charging and I swapped alternators with a new regulator in the newer one. Right away it over charged and I shut it down before it got too hot. That's when I started checking the wires, thinking it was something other than the battery now.

Thanks for the help, as always,

Bob

Once you have a good connection with the #2 wire to the stud/battery start it up and check battery voltage as it runs. You should get around 14-15 volts or so. Any higher then that after it has run for say 5-10 minutes the alternator V.R. may be going bad

Okay hold a phone a second, are you sure you have an internaly regulated Delco alternator? When you say...bottom wire on the plug in at the back... that to me is describes an early model that requires an external reguator. If it looks like the one in the link with a two spade plug in the side everything suggested so far applies.
Delco internally regulated example

Yes, "used red", I concur, it would be interesting to know if he has a tractor with:

...the original 10DN Delco alternator.
...a 10SI or 12SI Delco alternator that's replaced the original 10DN Delco alternator.
...a 10SI or 12SI Delco alternator that's replaced the original Delco GENERATOR.

That's interesting. What I had when I got the tractor about 25 years ago was one that looks like what you posted. t About five years ago that one finally stopped charging so I picked up one used at a salvage yard. It came off a chevy and everything looked the same so I put it on and everything worked fine for about the last five years.

My batteries were going south, but would still start and the charge would hold for about two days. When I had a complete dead set I had put a charger on them for a few hours, then started the tractor. I went to discing some stalks and walked around the front of the tractor and thought the alternator was making some noise and put my hand on it. It was hot then. It was daylight, but I often check the lights to see if I was getting anything off the battery and they were really bright.

I had another Chevy alternator that was a recent rebuild, but it had been on a pickup and looked and fit like the one I had on it. So I stuck another regulator in it and a 12 volt battery on the tractor. That's the last one I put on.

All this while I had been monkeying with the cables on the batteries where the accessory feed for lights and switch had been stuck on. So after some Googling I checked the wires on the plug and found the wires in the harness dead.

I guess what all this boils down to is what I have isn't OEM, but it looks the same and worked the same for a long time. It does have the internal regulator, both wires in the plug are dead, the battery feed is putting out 19 volts and the alternator is overheating where it wasn't before.

I know this is long winded, thanks a lot for the help

It is real easy to tell the 10SI form the externally regulated Delco alternator. The 10SI which has the internal regulator has a 2 wire plug that is flat looking and points at the armature where as the external regulated alternator has a square looking plug that runs parirel(SP) to the armature

The ones I've had on this tractor have always been the internal regulator. I've gotten into the wiring more now. I think the fella that I bought this off of had everything from a CD player to a television in his cab. There's a lot of accessory wires hooked up with eye connectors at the battery post.

I had never messed with any of that stuff as long as the tractor worked. I may just have to run a wire through the switch to the alternator for an exciter and hook up the hot output to the sensor wire spade. Then if that gets my charging going, I'll stick in a couple light bulbs and go back to discing.

Thanks again for all the help. Much appreciated.

Put a diode (1N5408 or equivalent) in the "excite" wire to prevent backfeeding and possible alternator damage.

<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIA1A.gif">

<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIB1A.gif">

<img src = "http://www.gondtc.com/~blweltin/Bob/AlternatorHarness3.jpg">

Not a 100 percent sure but I think originally tractor was equipped with a generator, which of course would have a seperatly mounted voltage regulator I think below the fuel tank. When you say...you stuck another regulator in it... does that mean you unbolted the two alternator halves and replaced the internal regulator, if you say yes to this we are now on the same page. Then all you need is terminal 2 looped back the back output stud and the terminal 1 powered on and off by the key. Also what no one else has mentioned the wire on the back to the post needs to be at least 10ga making a solid connection back to the positive battery terminal. On that model it can connect with the positive terminal on the starter. You don?t need a diode or anything in the terminal one wire because a diesel kills by cutting fuel at the pump not like a gas where the alt keeps feeding the coil and it won?t shut off. Just to clarify the separately mounted voltage regulator has nothing to do with an internally regulated alternator setup. And I also don?t care how long a post is if the problem is clarified and resolved for the original poster.

Great additional details, thanks Bob!

Test to see if e-mail is working

Yup. You not just kidding on the extra work you went to on all that, Bob. That helps a lot. I think I'll print that off so I can keep it handy.

Really appreciate all the help from everyone. Maybe I'll get a new tractor under the tree for Christmas?????

Thanks again and Merry Christmas to all of you.

Bob

Nothing would surprise me on this old girl, Used Red. A lot of the wiring harness is taped up and three or four colors in one line.

This alternator I took apart to halves and stuck another regulator in it. Those regulators are D668 s and internal. Most of the cases you can turn and orient differently to locate the plug and output wire. Some of that stuff is different on a car/pickup, but a lot of it's the same inside.

So having the information I got here, I put it together and brought up the power from the battery wire to the #2 spade terminal and started it up and got just under 15 volts charging and no heat. That was a relief. The exciter wire, though is still dead with key on and good battery. I don't see how that works, but since the thing charges right now, I'm not complaining and I greatly appreciate all the help.

Thank you all, Bob Martin