Onan Generator drain plug

[gprapim]

Can anyone tell me the drain plug size and thread pitch for a Jayco Class C Onan 4000 generator? I want to replace it with a Fumoto drain plug and don’t want to have to drain the oil now, until I need to, in order to measure the plug. Anyone?

[GMA385]

I have the Onan 5500 in my Precept and there is no drain plug but a petcock with a rubber tube that drains the oil. Not sure if yours is like that.

[gprapim]

Originally Posted by GMA385

I have the Onan 5500 in my Precept and there is no drain plug but a petcock with a rubber tube that drains the oil. Not sure if yours is like that.

No, mine has a drain plug under the cover plate, but thanks.

[GMA385]

OK sorry I was no help. Good luck

[MikeThompson]

I had a 4 kw a few years ago and put in a new drain. If I remember correctly, it was a 1\4" NPT.

[Les7h]

On the QD 8000 there is 2 possibilities - mine is 1/4 npt and requires an adapter to extend it enough to use the drain - ONAN can tell you if you have the serial number

[gprapim]

Originally Posted by MikeThompson

I had a 4 kw a few years ago and put in a new drain. If I remember correctly, it was a 1\4" NPT.

Mike, it is actually a 12mm x 1.5 thread.

[che57vy]

I tried to put one of the Fumoto drains on my Onan 4000 it also took a adapter, after I got it installed it was hanging down below the generator so far I was afraid something on the road would knock it off, like a truck recap laying on the road. I removed it.