Rebuilding a 10si alternator.

[mdm1]

I have a 10si alternator that is not charging. How hard is it to rebuild. I had it tested and it's only putting out 11.2v.

 

[Brown David]

https://www.google.com/search?q=Reb...1C1OKWM_enCA851CA851&sourceid=chrome&ie=UTF-8

 

[Duner Wi]

I can't think of an easier one to take apart.

 

[used red MN]

I have a 10si alternator that is not charging. How hard is it to rebuild. I had it tested and it's only putting out 11.2v.

It easy for someone like me that knows how to do it. There’s a rustred answer for you! It took me a bit to find a video that showed how to check the rectifier with an ohm meter but I found one. 10si repair video This guy shows testing them fairly early in the video. Also he shows disassembling the rectifier into two halves and repairing (soldering) a bad diode. I would just replace the whole thing if one shows bad.
At 28 minutes he shows checking the diode trio as well. Not sure if your electrical savvy, but he uses a diode setting on his meter. If you don’t have that your just checking the diodes on an ohm setting for continuity one direction and none the opposite meaning meter leads switched positions + and - on the diode. As he said the common person doesn’t have a way to test the regulator. My suggestion is if you don’t find a problem like brushes are shot or diode test bad or a short to ground in the stator or rotor replace the regulator.

 

[rustred]

I have a 10si alternator that is not charging. How hard is it to rebuild. I had it tested and it's only putting out 11.2v.

get your ohm meter out ,most times its the diode trio , regulator and brushes that get replaced. check the brgs. and replace as necessary. i always repacked the needle brg. i still remember when them brushes cost 3.00 at GM, in the 80's i used ether a piece of wire or a round tooth pick to hold the brushes in till it was assembled. and could hear each brush pop out when the toothpick was pulled out. we used to fix stuff not be parts replacers as they do now. repaired many many of them.

 

[mdm1]

I will check out all the responses. There is a shop by our cabin that does starter, alt work. I will attempt it myself but they are always an option. Thanks for the help.

 

[buzz saw]

You can bypass the internal regulator while still on the engine by using a pocket screwdriver or similar through the "D" shaped hole in the back of the alternator. That causes the alternator to go full field and maximum charging. I you do get charging at that point you have verified an internal regulator failure. I feel sure there would be a video to show that somewhere on the net.

 

[buzz saw]

It easy for someone like me that knows how to do it. There’s a rustred answer for you! It took me a bit to find a video that showed how to check the rectifier with an ohm meter but I found one. 10si repair video This guy shows testing them fairly early in the video. Also he shows disassembling the rectifier into two halves and repairing (soldering) a bad diode. I would just replace the whole thing if one shows bad.
At 28 minutes he shows checking the diode trio as well. Not sure if your electrical savvy, but he uses a diode setting on his meter. If you don’t have that your just checking the diodes on an ohm setting for continuity one direction and none the opposite meaning meter leads switched positions + and - on the diode. As he said the common person doesn’t have a way to test the regulator. My suggestion is if you don’t find a problem like brushes are shot or diode test bad or a short to ground in the stator or rotor replace the regulator.

I've rebuilt a few of these in my time....Only insert metal screwdriver 3/4 inch or so, you will feel a tab and ground tab to case of alternator, if you miss the tab and go too far you will get into the rotor.

 

[Jim.ME]

Another picture of the test tab. Not all have them I have found.

 

[Gambles]

As posted previously, they are probably the easiest alternator to rebuild. I used to maintain a fleet of about 30 forklifts and because they are the cheapest to rebuild or replace, the factory owners had me convert everything to the 10i if it was possible and if it previously had something else. (I still remember putting a 10i on a Bobcat skid-steer that previously had an expensive Korean Mando on it) Most replacement parts are fairly inexpensive, at least from RockAuto, and they also still sell rebuilt ones that are relatively cheap. (Yea, we still have to consider RA shipping) OP: You never said the application and you never said if the is a one-wire or a regular alternator.
Just curious here: Since it looks like you won’t be rebuilding it yourself, what does a shop now charge to rebuild it?

 

[mdm1]

This is off of an Allis C tractor that has been converted to 12v. It's a regular alternator not 1 wire. Sorry about the lack of info. I will try it myself. If it doesn't work out I will post the rebuilt cost from a shop if I go that way.

 

[560Dennis]

If I still have it , i converted the 10Si to 6 volt positive ground for the Super C. If still have the 12 volt regulator ,I’ll send it to ya. Got to look .

 

[Mike(NEOhio)]

Usually all they need it the sliprings cleaned up, maybe new brushes or diodes. Back whey I drove Scouts they had only a 37 amp and every year or so I would notice the lights dimmer and the wipers slower. I knew it was time to do it. I clamped the front housing to my bench by the ear so the pulley was down. One of the bolts in the drill to drive the shaft and a fine file to smooth the rings an it was good to go.

 

[ole fred]

Years ago, I ran two 10DN's on my 69 Freightliner. I had two of them. One drove off the crank and the other off the accessory drive. Corrosion on the stator windings always got them. Back then, I could buy new 72 amp stators for $10. Not anymore. I still have one in the original box.

 

[mdm1]

I have taken it apart and the rotor, stator, and slip ring checked ok. Not much left of the brushes. I'm going to clean it up and install all new parts inside and see how it goes.

 

[Jim in LA]

YouTube has rebuild videos.

 

[Brown David]

YouTube has rebuild videos.

Very first reply has links to several.

 

[mdm1]

I did watch some of those. Thanks

 

[Hobo,NC]

I have taken it apart and the rotor, stator, and slip ring checked ok. Not much left of the brushes. I'm going to clean it up and install all new parts inside and see how it goes.

To check a rotor if it passes a ohm test next you use a battery charger. You touch one slip ring with the positive and the other with the negative its been awhile it should pull 1 to 2 amps if my memory is correct. Its not much and it not a dead short.

If the stator passes a ohm test a common issue with them is a loose end see if you can make a eyelet move. I sandblast and solder them all wink wink.

That's two issues you may not find on yourtube.

Checking the dio trio and rectifier should be a no brainer. Always remove the rectifier to check it as it can be a ground issue rectifier to alt body ground issue.

 

[used red MN]

I did watch some of those. Thanks

I hope you watched the video I linked in my reply 4, the majority of the others that came up when I did a search such as his link contained did not. I probably shouldn’t open with a sarcasm like that, but I do know how to rebuild them, done many of them.