Onan Oil Drain Plug Issue

[Craig P.]

I normally do my own routine generator maintenance. Last year my generator was due for it's five year service, so I opted to have it serviced by an authorized Onan service center. That turned out to be a big mistake. They improperly installed the fuel filter which resulted in diesel fuel squirting out all over my RV pad, and an immediate return trip to the service center. Here I am one year later, and that visit still haunts me. The generator is now due for an oil change, so I gathered the appropriate supplies to perform what has always been an easy job. One grunt with my ratchet and I discovered that the idiots re-installed the oil drain plug with an air impact. I couldn't get it to budge. Repeated attempts left me with a rounded drain plug head. See below photo.





I tried everything in my tool arsenal to remove the plug, but I only made things worse. I did a little Internet research and found that Sears sells a damaged bolt removal kit, so I drove to my local Sears and picked one up. Luckily for me, they were on sale for $18. I then drove to my local RV parts store, and to my surprise, they had a replacement drain plug in stock.





I was able to finally remove the damaged drain plug with the Sears removal kit. It required the use of a breaker bar, which had mr worried that I would snap off the head of the plug, but with some praying and finesse, I finally got it out.

Onan obviously re-designed the drain plug. As you can see in the below photo, the original drain plug had a small 3/8" head, while the new plug has a 9/16" head. The larger new head should prevent this from happening again, as long as another "authorized" Onan service center doesn't get a hold of it!





My Onan is a 7.5, model HDAKJ. If you have the same or similar model Onan, take a look at your drain plug. If it has a small 3/8" head, it might be worth the trouble to replace it during your next oil change. The new plug was only $2.98, so it would definitely be worth the investment.

Craig

[jfran304]

Better yet replace your drain plug with the Fumoto valve. That way you don't have to unscrew it anymore. If you get the Fumoto valve with the nipple you can attach a hose to it when you drain the oil and it won't get all over everything. Call them with the size of the drain plug and they will match you up with a Fumoto if you can't find it on their website.

Lubrication Specialist: Engine oil drain valve made by Fumoto: The best way to change the oil quickly and easily!

Jon

[Craig P.]

Quote:

Originally Posted by jfran304 Better yet replace your drain plug with the Fumoto valve.

I agree with you in theory. I say that, because I ordered a Fumoto for my Cat engine, only to find that the threads didn't match, even though the distributor insisted it was the correct valve. I was out the money so it turned me off on them, so I didn't consider it for the genny.

Craig

[dons2346]

Quote:

Originally Posted by Craig P. I agree with you in theory. I say that, because I ordered a Fumoto for my Cat engine, only to find that the threads didn't match, even though the distributor insisted it was the correct valve. I was out the money so it turned me off on them, so I didn't consider it for the genny. Craig

Why didn't you go back to Fumoto and get the correct plug?

[Craig P.]

Quote:

Originally Posted by dons2346 Why didn't you go back to Fumoto and get the correct plug?

I didn't buy it directly from Fumoto, I bought it from an online dealer.

[Monacoach]

Went through the exact same situation ( stripped plug, pried it off with that special socket and a long pipe for leverage), except RV dealer did not have the plug in stock so I reinstalled the stripped plug. I didn't tighten it to much so hopefully it will come off easy next year.

[Bob and Inga]

Who did the hack job? Should also post them on:

RV Service Review

Bob

[Craig P.]

Quote:

Originally Posted by Bob and Inga Who did the hack job? Should also post them on: RV Service Review

McBride's RV in Chino CA. I love RV Service Reviews. I posted my review on them already.

[Iron Man]

Every Onan I have changed the oil on has had a tight drain plug. On 2 12.5 kw I did the first oil change and had to use a 24 inch breaker bar to get the plugs out. They seem to tighten on their own! Use a six point socket and make sure it is on square.

[RVThere]

Thanks Craig.

You showed a picture of a tool I didn't have so Sunday morning DW and I went to Sears to buy a set (you never know when you'll need it...)

But of course there is the $59.99 set that goes up to a 3/4" nut and you can put on your impact wrench!

Last time I took the wheels off my truck I had to cut a notch in the nut and beat three of them off with a chisel. Hopefully this tool will work better than that solution.

[Harm]

Craig:
Thanks for the heads-up.
Do you happen to have the Onan part number for the new plug?

[Mr_D]

Quote:

Originally Posted by Harm Craig: Thanks for the heads-up. Do you happen to have the Onan part number for the new plug?

Looks to me to be a common brass pipe plug. The threads appear to have a taper to them. Should be able to match it at any good hardware or plumbing store.
I've thought about the Fumoto valve, but the MH engine pan is already pretty low and the Fumoto would hang down another ince or so with no protection. The only thing that would be easier would be getting an oil sample, but I've never done that yet.

[fla tom]

Did my first ( 5ohr )oil change oil plug had blue locktight on it

[toneumanns]

The same gorilla that installed your drain plug must have installed my oil filter! Thought I would never get it off & the case was so twisted that I was afraid it would tear apart.