Stuck Generator Oil Filter

The problem on the ONAN, at least the 5500, is that the filter is recessed into the gen set and only protrudes maybe an inch or two. This makes it hard to get most strap wrenches onto the filter. Onan makes a cup wrench just for it's filter but the filter is now probably distorted too must to use a cup wrench. There also is not room to drive a large screwdriver through the filter but that is probably the answer. Good luck and if you get it off, I would suggest you buy a ONAN cup wrench for next time.

You might try to tighten with good strap wrench an than try to loosen holding all tension you can for period of time an it might let loose.Might just have to get madder for a minute or two!We always had that trouble on a Lycoming aircraft engine an we installed them!

My last resort is an oil filter wrench where the "strap" is a chain. It may crush the oil filter canister, but it has never failed to remove it.

Big Katuna wrote:


Onan has a Gorilla at the factory putting those on. Drain plug too.

Maybe there is a Fumoto valve available to replace the OEM drain plug ???

I 3rd (or 4th?) the screwdriver suggestion. Ram a BFS through it and it will come out no problem. Great way to alleviate you frustration with it, too. Put the new one in hand-tight with a bit of fresh oil on the seal.

Have you tried a metal strap wrench? The plastic/rubber ones dont grip. Metal ones come with chain type or flat strap. Get as close to the base as possible.

Onan has a Gorilla at the factory putting those on. Drain plug too.

Drive a couple of scewdrivers into the end of the filter and use a pry bar between the scewdrivers

I,ve poked a hole in them and used a long screw driver, the closer to the front the better , and right at the very front the casing has a lip on it if you can get the pliers on it.

Not sure you have room but -

As a LAST resort, I have in the past taken a hammer and screwdriver and pounded the screwdriver completely through a filter so it sticks out both sides. You then can grab the screwdriver and twist it to loosen the filter. As you might expect, it makes a big mess. You will want to insert the screwdriver nearer the genny as opposed to the end of the filter.

* Or you could drill holes on both sides and then insert a screwdriver.

And no disrespect intended, but make sure you're twisting in the correct direction.