GEN Lights

[blackhueys]

Since alot of people seem to be encountering this I will tell you what finally did the fix for me and only cost 25.00. First I had the Alternators rebuilt helped some but problem still there fan on high etc. Well got bored yesterday and pulled them out and tore them down found out that the shop never replaced the diode trio or the voltage regulator, well went to the local parts place and picked up two of each and so far no lights at all. the voltage gauge stays put right in the middle of the green regardless of what I do all lights on fan on high or low rev it up and down nothing makes the gauge move anymore! Voltage test front battery running is at 14.50 volts rear battery running is at 14.45 volts and together about 28 volts constant! just thought I would share my fix and the alternators really are not that scary once you get them apart and see.

 

[OL AG '89]

what did you pay for the alt rebuilds. I've gotten some OUTRAGEOUS prices so far.....

 

[Warthog]

I pay about $85 locally or I can get a complete rebuild kit for $40

The alternator is just a 27SI type 100 GM alternator. Only special parts are for the isolated ground and they can be reused (nuts, bols, washers)

 

[Warthog]

....shop never replaced the diode trio or the voltage regulator, well went to the local parts place and picked up two of each and so far no lights at all.

The diode trio is one of the most common items to go out. And they just cost a few bucks to replace.

Good job....

 

[blackhueys]

well both alts rebuilt (ha ha right) was 125.00 considering that they where told to replace everything except the stator, case half's and the armature I was not happy to find out that they did not do that. i asked them to do this because of what I read on here about the diode trio causing gen light problems. I will be doing my own rebuilds now the only thing that I wont be able to do is test the stator and armature (I dont own a growler tester) these I would still take in and have tested. From start to finish both alts was about a hour rebuilt them on the pass seat!

 

[skysix]

Do you know what the part number or size/amp rating of the diodes are? Might be a good idea to get a set of 6 and swap them before I start digging any deeper into issues...

 

[blackhueys]

I just asked for the ones for a 27si alt 12 volt 100 amp

 

[Warthog]

The diode trio is a sealed unit of thre diodes in one unit. They cost just a few dollars. Here is pic of one being tested.

Download the TM 9-2320-289-34 and study the section on rebuilding the alternators. All the parts are illustrated