Onan 4000

[katiedog]

I have a 2016 Jayco with Onan 4000.
At 790 hours it stopped making A/C
after all testing seems the brushes are worn down
past limits.
After checking with local Cummins dealer
on wait times , about 4 weeks.
We decided to do the job ourselves..
I have replaced brushes on several gen-sets
but the KY 4000 is different. Completely!!
Full removal and disassembly of Flywheel.
All done but wonder what this job would have cost
at a dealer. Anyone have this done on a KY 4000 spec p ?

[craigav]

I don't know the R&R costs, however I have a question, were the brushes worn out or were they damaged\dirty? I have seen other Onan 4000's with over ~2000 hours running fine with the original brushes. ~CA

[katiedog]

The brushes were worn to 50% on one and 75% on the other.
The shorter one was tapered on one edge badly.
Slip ring was was very dirty and a little rough on that side also.
This is my 3rd KY 4000 and never had to service the generator
side.
Maybe just bad luck

[craigav]

I have on a few occasions boondocked in dusty conditions where 4 wheelers were playing. I wonder if perhaps dusty conditions attributed to the wear? In any case, thanks for your information and I will give more thought into where I boondock in the future if dusty conditions exists as I never thought about the brushes and instead only thought about the air filter and the overall dust concerns. I suspect I could change out the brushes as well, but prefer not to have to do so... at least not for a very long time. Mine onan has ~350 hours.

[katiedog]

We boon dock all the time in Dusty areas.
Not sure if that contributed.The area under the flywheel and
Brush holder looked brand new.
Only Carbon from worn brushes was present.

[craigav]

Thanks for the additional information. I like to boondock when I can as well, dusty or not, and I enjoy 4 wheelers (:>). Anyway, with your last comment, I will not worry as much about the dust as I may would have had otherwise. Thanks, CA

[GeorgiaRV]

We boondock 98% of the time in ours. A lot of times in dusty areas. I have about 890 hours on mine, knock on wood, no issues so far. I know I shouldn't be typing this out...
:-O

[craigav]

FYI, If anyone wants the service manual for the Onan 4000 KY, I found it here. ~CA

https://www.manualslib.com/download/...00-Series.html

[Tgroves526]

Reading this posts, would you guys blow out the flywheel area? anything proactive to extend its life?

[craigav]

Originally Posted by Tgroves526

Reading this posts, would you guys blow out the flywheel area? anything proactive to extend its life?

While I haven't ever replaced the brushes in an Onan generator, I have replaced them in other things such as welders and alternators. My thought would be that blowing out that area with high pressure air could actually introduce dust into the areas where you don't want it and instead of prolonging the life of the generator could reduce the longevity of the generator. Keeping the entire area clean though certainly would be best and keeping up with all of the maintenance, especially the part about changing the oil often. I also would not recommend cleaning it with a pressure washer, same as for your engine and similar components. ~CA

[katiedog]

I agree , I would not blow out brush and armature area.
Other than a little carbon dust I have found that area clean.
Unfortunately there is no way to clean and polish the slip rings on this unit
that is only maintenance needed in this area on most Onans

[katiedog]

Our Onan is running fine after replacing the Brushes.
I did get a replacement control board from flight Systems.
Tom their tech was very helpful but
Turns out the Onan control board was fine.
Tom said he would not of thought the brushes would be worn so early.
I am going to sell the onan control board.
4 years old, seems fine $150.