I do power maintenance for AT&T and we use Onans as well as many others from 10kw to 1mw. 10k hours is a lot of use. One shouldn't worry about the alternator
(generator portion) so much as the engine itself. The only problematic item for the alternator
are the diodes breaking down from heat and use. These can be near impossible to find for older units if there aren't generic replacements
We have several Cummins powered gensets that are 40 years old but have only 2-3k hours on them, but even so, a regular maintenance program and logging what and when it's done becomes critical at this age to keep track of changes in the set. Good oil pressure is absolutely critical to the life of the engine. More frequent oil changes and maybe a change in the grade of oil used (i.e. 15w-40 change to SAE 40). Consult a Cummins certified engine shop (NOT ONAN) for the best way to keep up with the high hours. Does she use any oil? A preventative rebuild
should be planned for in the future to change out rings, bearings, and seals
and have the head
worked over. The block should last near forever if the "wearable" parts
are replaced in a timely fashion.
Don't wait til it dies mid-passage.
"Behind every great man there is a woman, rolling her eyes."
But not for long! Now she's gone!
and peace and tranquility reign forever!
1969 Morgan 40 Cruising Ketch