Our local Cummins/Onan dealer told me they routinely see the bigger Onan QD gensets go up to around 20k hours before any major work/repairs are needed.
That said, there are some service procedures that should be performed around the 3k hour mark.
When we purchased our 03 Dynasty it had approx. 2700 hours on the Onan 10k Quiet Diesel genset, I thought it was a lot but relaxed after talking to our Onan dealer. Upon doing most of the preventive maintenance on our coach upon taking ownership of it I tore into the genset and noticed that the belt was on its way out. It had a couple of nasty chunks taken out of it. I removed all of the covers and performed the 3k hour service a little premature but I am glad I did. I also changed oil, coolant, all of the filters, flushed cooling system, washed the radiator off and adjusted the valves. The valves actually didn't need adjusting as they were fine but the FSM recommended adjusting them. The tech at the Onan dealer also told me to not worry about the valves as he has never seen them out of adjustment until closer to 10k hours, however, I am a stickler for following the factory recommendations.
Ours currently has just over 3k hours and runs like a top. We have only put a few hundred hours on it in the six years of ownership.
Mike.
