50Dn Alternator

[Gary W]

The alternator is not charging all the time now, when I first start up it seems okay for a while then the not charging lite comes on and the volt meter drops from about 28 volts to 24. Could it be the voltage regulator or is it the alternator . I have 6v92 in 1986MCI 102A3.

Gary

[richard5933]

The alternator is not charging all the time now, when I first start up it seems okay for a while then the not charging lite comes on and the volt meter drops from about 28 volts to 24. Could it be the voltage regulator or is it the alternator . I have 6v92 in 1986MCI 102A3.

Gary

Have you double checked all the cables and wiring to make sure there are no loose or corroded terminals? Don't forget about the ground connections. If you have a problem here your troubleshooting will be difficult.

[Ed Hackenbruch]

Gary, the not charging light will come on when your batteries are fully charged.....if you turn on your headlights and a few other things to draw the batteries down some, that light should go off as the alt. starts charging again.  I always ran with my head lights on for safety and so the not charging light would stay off and not distract me going down the road.  

[lvmci]

There is a problem with 102C3s and other 102s that has to do with the tripple 7 safety  switches, that was corrected on later numbered chassis, with a 2 part kit, and new regulator part, expensive.
My not gen light flashed on and off, sometimes the check starter light came on with it,  causing no alternator charging, killing of my tachometer,  which is run off the back of the alternator. It did this for awhile, just lasting seconds, my mechanic couldn't find it, till it stayed on and exposed this factory design fault, there's a by pass for just a short time, but it can cause issues, if you leave the batteries on while engine is not running, according to Stewart and Stevenson knowledgable mechanics.
The drop from 28 volts to 24 volts is the alternator not charging and just batteries supplying power to whatever 24 volt electric draw is going on...lvmci...

[lvmci]

Heres the Dual function replacement service bulletin of the Triple function causing the "no gen" light and no 24 volt charging issue, lvmci...

[windtrader]

The 8v71 maintenance manual shows a special alignment tool (20-157)when servicing the 50DN. Can the bearings be replaced and alternator reassembled without this tool? How many of you have one? Is there a busnut tool lending library?
There is a reference to 100-300k as an inspection interval. I could not find the reference to pulling it out and replacing bearings.

[chessie4905]

Heres some info on the belt driven version.
https://www.elreg.com/blog/delco-50dn-alternator-is-dependent-upon-proper-oil-flow/