92GA said:
I agree. What I'd do is get a stainless nipple about 1 inch long, measure how many threads are showing when inserted. Then take it back out cut the end off so it doesn't go in too far. Clean all the oil from the threaded area and insert the nipple using red locktite . Let it dry and install a brass valve on the nipple with a plug to remove to change the oil. The locktite will bond the aluminum case and stainless together. It can be removed if needed with a little heat on the nipple.
My oil pan is not cracked (yet), but, yes, I think that I get what you are saying here...and it would work even better if Onan hadn't designed the drain hole with 2/3 of the threads above the bottom of the oil pan, necessitating the "cut-outs". UNFORTUNATELY, because of Onan's design, ANYTHING that is going to remain in the drain hole during oil draining can only occupy the bottom 3 threads if a complete oil drain is desired...otherwise you'd leave approx. 1/3" of oil in the pan because the "cut-outs" would be blocked. 3 threads might be enough, especially if sealant/Loctite is used, and it might be worth trying just to avoid having to ever remove/replace anything from that drain hole again, risking stripping the aluminum threads and/or spreading the upper cut-out 2/3 of the threads apart to the point that they might even break off in the oil pan...I don't know how well attached they are in there.
If Rene T's drain cock has enough threads on it to achieve the same tight fit as the nipple above would, without bottoming out on the hex head on the drain cock, the ideal setup would then be the drain cock, cut down so that only 3 threads are being engaged into the oil pan hole, semi-permanently "glued" into place with sealant AND using a washer/gasket combination (as insurance against leakage). I'll have to spend some time at hardware and/or auto supply stores this week to see if I can find a drain cock or anything else made of brass (or steel???) in 1/4"-14 NPT that has enough threads and/or space near the bolt head to allow for 3 tight fitting threads AND a washer/gasket under the bolt head, keeping in mind what Rene T had mentioned: "you would want the flange to make contact with the gasket at the same time you ended up with 100% thread engagement." Hopefully, if I spend enough time in stores I can find something that will satisfy all of the above requirements and I won't have to worry about damaging my oil pan ever again. If nothing else can be found that is more convenient, then I'll go with the nipple method. I've even thought about getting a suction device to just remove the oil out through the dipstick/fill hole, but I'd still want to have a workable drain option because the next owner might want to go that route and I wouldn't want to have to tell him that if he removes the drain plug he might have headaches trying to replace it without causing damage or having it leak. Something that is installed semi-permanently into those 3 good available threads will prevent those potential problems and still allow for complete draining of the oil in the oil pan, if/when a suction device is not used.
I was wondering about the choice of stainless steel vs. brass for the nipple...you had stated "The Loctite will bond the aluminum case and stainless together"...is the Loctite able to bond better to steel than to brass, and if so, would it matter if it was stainless steel or just steel? I'm also wondering if I could use blue Loctite instead of red, to make possible future removal easier? Or is there a sealant out there that both seals and bonds that would do those two jobs better than Loctite?
Thanks to everyone for your help with all of this. My ALL CAPS comment to Brad (who said "sorry for derailing..." and then proceeded to derail) was just frustration with constantly having to wade through off-topic posts to find the on-topic posts that might actually help with the problem being researched. Yes, off-topic posts can be educational, too, and if I had unlimited time I would love to read all of them, but I'm trying to get my MH ready for a 1000 mile trip with my 91 year old frail mother aboard to move us to where my brother moved to, and need to get my MH quickly into great, safe condition...and I'm having to do this while serving as a nearly full-time caregiver to my mother, who lives with me. I haven't really had a day off in over a year, and so my patience is pretty thin. Perhaps I could have not used ALL CAPS, but I still believe that if everyone just stuck to the topic of the thread, it would make for a more efficient forum. Yeah, I know...I'm not on topic here...hypocrite, right?...but since this can was already opened, I thought I should explain, and also I wanted to make sure that no one thought I was addressing Gary with my ALL CAPS comment. I quoted Brad's derailing post, but since my ALL CAPS comment appeared right after Gary's post some people might have thought that I was addressing Gary's comment instead of Brad's. Part of the problem is that, in this forum, posts seem to appear chronologically regardless of whose comment you are replying to and quoting, as opposed to some other forums where your reply to a person's post appears as a sub-post to their post. There are good things to be said for both styles, though.