3G alternator help - low voltage

Booyah45828

Full Access Member
Joined
May 2, 2017
Posts
879
Reaction score
671
Location
Ohio
You can buy the rectifiers cheaper then that. Doesn't take much to swap one out.
 

Booyah45828

Full Access Member
Joined
May 2, 2017
Posts
879
Reaction score
671
Location
Ohio
Typically you can hear the alternator whining if the diodes failed like that, but with a diesel clattering below it, you might not. The shop truck's alternator(chevy 1500) is whining like that at start up, I just haven't looked into it yet.
 

renjaminfrankln

Full Access Member
Joined
Aug 27, 2018
Posts
583
Reaction score
322
Location
Raleigh NC
You can buy the rectifiers cheaper then that. Doesn't take much to swap one out.


Really appreciate your help in diagnosing the problem. If a replacement was $150 I would be tempted but with a name brand reman available for $90 shipped with tax, I'm just going to go that route.

Also if any oilburners want my old alternator, you can have it free local pickup in Raleigh, NC. Has a brand new regulator!
 
Last edited:

aggiediesel01

Full Access Member
Joined
Dec 29, 2016
Posts
531
Reaction score
417
Location
Houston, TX
I used the 200 amp rebuild kit from these guys when I did mine a couple years ago. I was pleased with the bearing quality and increased size of the copper windings in the stator and it’s still running great. Yes this kit is for the ‘92 and newer style 3g but I believe it’s the same for the v-belt version. And if you’ve never done one before their how-to video is very detailed and shows every step clearly.

http://starteralternatorrebuildkits.com/product/7768/
 

Booyah45828

Full Access Member
Joined
May 2, 2017
Posts
879
Reaction score
671
Location
Ohio
Really appreciate your help in diagnosing the problem. If a replacement was $150 I would be tempted but with a name brand reman available for $90 shipped with tax, I'm just going to go that route.

Also if any oilburners want my old alternator, you can have it free local pickup in Raleigh, NC. Has a brand new regulator!

Not a problem.

If you have it off, you can take it to a napa or oreilly store and have it tested to see what they say, make sure they do a ripple test to. But with 30 volts of ac, you definitely have an issue.

You can also use the diode function on a multimeter and check the diodes in the rectifier.
 

typ4

Supporting Member
Supporting Member
Joined
Dec 24, 2005
Posts
9,093
Reaction score
1,372
Location
Newberg,OR
Hook the yellow sense wire to the battery instead of the alternator and see what it does
 

typ4

Supporting Member
Supporting Member
Joined
Dec 24, 2005
Posts
9,093
Reaction score
1,372
Location
Newberg,OR
Take alt to an electric shop, get it tested to see what the actual regulator set point is
 

Forum statistics

Threads
91,217
Posts
1,128,517
Members
24,045
Latest member
Ramtough01

Members online

Top