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Darryl · 08-23-2009, 03:34 PM

I went to change oil in my Onan 6500 Marquis today and the nylon oil plug just sheared off. I changed it last year with no problems. Maybe the heat has weakened the plug. It seems crazy to put a nylon plug in an oil pan to begin with (to me).

If you remove the small cover underneath (where the oil normally drains out) , you can see the big plug threads. It is the part outside of the generator that sheared off. I don't know why it was so hard to remove. I'll bet I'm not the first to have this happen though.

Any advice from anyone on getting this out? Whatever I do will pretty much need to be done from underneath. The "thumb" part that sheared off is very close to the frame rails and you really can't get anything into the hollow plug from the end. I'm guessing here. Maybe it isn't hollow at all. I had thought abut putting something like an easy-out into the end of it if it's hollow. Can't really tell because of where it's located.

AFChap · 08-23-2009, 10:28 PM

I haven't seen a nylon plug in a generator, but I have had this problem in an Atwood water heater. I flush my WH 3 or 4 times a year and NEVER re-use a nylon plug more than once as they do get hard/brittle from the heat. The WH plugs are hollow, and when they break the contents of the WH drain. Then the threads still in the heater can be removed with anything that will grip them. I have used a hunting knife that I can push into the nylon and then turn with the help of a pair of pliers.

If the plug sheared off and the contents have NOT drained, I would drill hole into the plug to drain the oil out, then use an easy-out, knife, or anything else that would grip the nylon.

J Walker · 08-24-2009, 09:07 AM

Ditto AFChap. It will be a nasty job. Let it drain from the hole you drill overnight and maybe you won't get oil on your face. A hacksaw blade might cut the plug enough to get it out.

Darryl · 08-24-2009, 11:30 PM

I finally called a local generator repairman about this problem. He let me in on a secret for this oil plug. The plug is hollow and at the end of it is a square fitting that fits a 3/8 extension. We were able to insert an extension into it and backed out the plug. In addition, the frame of the genset has a hole made into it that allows the extension to fit through to the plug. Hope this helps someone else.