Gen Hours

We are interested in buying a used RV. They often tell us how many hours are on the generator. What is the life of a generator? What would be considered low hours vs. high hours?
This info would be so helpful to know if what we are looking at is "very used" or a good sale.
Janet, (Worcester, MA)

Janet, RV-approved generators are sturdy units, but extended use without proper maintenance can take its toll over time. This toll is somewhat predictable, however, and manufacturers usually specify maintenance and inspection intervals based on the number of operational running hours such as every 50, 100, 200 and 500 hours. It's impossible to determine just how many hours per year would be an average. And keep in mind, a well maintained generator will last indefinitely. 

With all the amenities found in the typical campground today it would probably be rare for the casual RVer to rack up more than 150 hours or so per year. Unless of course, they spend a lot of time off the beaten path or at tailgate parties, (many do both).

A generator load bank test can be performed to determine how well it responds to varying loads. This will provide some indication to its general state of well-being. Many proactive RV shops will offer this service. If you have a serious concern about too many hours based on the year of manufacture, the only true way to determine how hard the generator has been operated is to remove and inspect the cylinder heads. A close internal inspection of the heads will reveal to what extent the unit has been pushed (see photo). Carbon buildup and cylinder wall scoring, etc., all provide clues. But even if it has a ton of hours and the owner can verify that the manufacturer-recommended maintenance interval checks were performed, I wouldn't be overly concerned. It wouldn't be a deal breaker, but perhaps a negotiating chip!