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Joe, Marine Mechanic
Category: Small Engine
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine inboards and electronics, automotive drivability, all around repair tech,
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I'm looking at buying a motorhome that has a diesel Onan

Customer Question

I'm looking at buying a motorhome that has a diesel Onan 7500 generator on it and wondering how many more hours I can expect to get from it before needing an overhaul. It starts and runs fine now...
Submitted: 1 year ago.
Category: Small Engine
Expert:  Joe replied 1 year ago.


Thank you for allowing me to assist you, my name is Joe and I will be happy to assist you with your concern today.

When these are correctly maintained and well taken care of they can go for many hours, so much so that there is really no way to put a number on it. With that said you would want to check things like overall visual condition, compression test, just look at how it has been taken care of and it will show.

Again there's absolutely no way to say how many more hours you may or may not get out of it.

Thank you!

- Joe

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I'd be happy to answer any other questions you have even if not related.

Customer: replied 1 year ago.
The generator has 5000 hours on it. I would just like to know what is the average life of a well maintained diesel generator.
Expert:  Joe replied 1 year ago.

That is what I was trying to explain, there is no average life span.... any given are usually given on speculation, this is based on what that person has heard or seen other engines last until, this however generally changes person to person and you could go to 5 different shops and have each one give a different figure. This is because it is all in how well something is taken care of and maintained, the average gas engine will last 5-8000 hrs, diesel will be up around 20,000 and non natural aspiration will reduce life as it is harder wear and tear. Again with that said it's not to say you could not double or triple those hours if it has and continues to be well taken care of. I have also seen perfect maintained engines bad almost new, there are too many variables.