Forum Discussion

AH_AK's avatar
AH_AK
Explorer
May 02, 2021

Built-in generator oil change

The built-in generator (Onan 2500 LP) in my Bigfoot needs an oil change, but you can’t access the drain plug from below (battery compartment). Anyone done this? Do you just unbolt and slide it out far enough to access the drain plug.
  • jimh425 wrote:
    I suck mine out the fill port.



    Thats what she said..

    Quote the Office
  • On my old AF1150 the hole in the "shield" didn't line up with the drain plug. I took a Dremel and made opened the hole to an oval shape to allow me to access the plot
  • AH_AK wrote:
    Great idea. I think pumping it out of the fill tube is far preferable to removing or drilling holes.


    Yes and I agree to the three above. That's how I did it before I took it out and threw it in a ditch.
  • Great idea. I think pumping it out of the fill tube is far preferable to removing or drilling holes.
  • I would probably just suck it out the fill port. There are vacuum pumps made for this. They are most often used to change the oil on inboard boat engines. A look thru a marine website for oil change pump should get you there.
  • If you do get it out, maybe a Fumoto valve would work, Instead of drilling a hole, you can attach a hose to drain.

    I have used them in my trucks for many years.
  • Slymer wrote:
    Our AF811 has the same generator. I was able to access the drain plug but just barely. Once I found the correct socket & extension bar I had to get it ALMOST on the bolt, on quite an angle & whack with a hammer a couple of times. The bottom cover plate finally shifted over a bit to get the socket dead on. Not easy,....even harder to replace the bolt. You may have to drill an access hole through the bottom cover plate in your set up.

    So yours had a hole drilled for the drain plug when you bought it? That would make sense but it doesn’t look like mine has such a hole. There is an angled hole to the battery compartment (below) but that appear to be an access for the spark plug (per onan manual).
  • Our AF811 has the same generator. I was able to access the drain plug but just barely. Once I found the correct socket & extension bar I had to get it ALMOST on the bolt, on quite an angle & whack with a hammer a couple of times. The bottom cover plate finally shifted over a bit to get the socket dead on. Not easy,....even harder to replace the bolt. You may have to drill an access hole through the bottom cover plate in your set up.