soyjer said:Onan changed the drain plug thread from 1/4"-18 NPT tapered thread to a 3/8" standard (NON-tapered) course thread, in conjunction with adding the plug flange and the sealing washer,
92GA said:If that were mine I'd still get a stainless pipe nipple and screw it in, mark it then take it back out, notch the nipple to match the notches in the pan, then use a thread locker for sealant. Then install a brass ball valve with a stainless plug. That way you won't just have 3 threads to seal it with. That is a poor deal in my opinion, can't believe onan would engineer something like that. Don't see how they could ever keep that from leaking.
soyjer said:Yeah...I can't think of a scenario where having the drain hole extend below the bottom of the oil pan would be a problem, so I don't know why they would have gone with this "cut-out volcano" design. Your fix would be the way to go if draining out of the drain hole were required, but thankfully this thing only holds 1.6 quarts of oil and so I'll just use a suction device once I get the drain plug to stop leaking.
I was actually hoping to hear from people with experience with aluminum oil pans telling me that the factory specified 21 lbs-ft is just fine, but instead I only heard from people telling me just the opposite, including an Onan engineer with decades of Onan experience, who told me that 21 lbs-ft was too high and that 5-8 lbs-ft sounded about right. The factory specified 21 lbs-ft may, indeed, be just fine, but even 15 lbs-ft was feeling very risky to me as I tightened the plug, and a new oil base is about $150, and so I wanted to be as cautious as possible to avoid cracking or stripping the oil base, if possible. I have no way of knowing how many of these 1/4-18 NPT thread oil bases have been stripped or cracked over the years by oil changers using the factory specified 21 lbs-ft, but Onan DID redesign the oil base hole and plug with SPEC L to an M12-1.5 NON-tapered thread hole and a plug with a flange and sealing washer, and so there MUST have been a REASON for that change being made...such as leaking drain plugs or stripped or cracked oil bases?
srs713 said:From my experience with aluminum motorcycle engines and their oil drain plugs I'd believe 21 inch/lbs before I'd crank a plug to 21 ft/lbs.
Those things go on just a bit past finger tight! Old mechanic taught me to twist it on, then give it a light tug with a wrench, no more.
soyjer said:Regarding my other question about slow oil refilling, I learned today that the problem is that the air above the oil in the oil pan must pass through a tight restriction to reach the valve cover area, and for that reason you must "pump" out the air as you are adding oil in order to be able to quickly refill the oil pan with 1.6 quarts of oil. Fortunately, the breather valve that allows air out of the valve cover area into the atmosphere is a one-way valve, and so you just need to remove the rubber hose from the fitting on the top of the valve cover, then connect a 1/2" I.D. tube connected to a syringe or turkey baster to the fitting on the valve cover, and then pump the syringe or turkey baster to draw air from the oil pan through the "tight restriction" and pass it out the breather valve as you are adding oil to the oil pan. Be careful not to add more than 1.6 quarts, and I'd advise pausing at about 1.3 quarts and maybe turning over the engine before proceeding further, because I'm not sure that the oil pan will hold the full 1.6 quarts without doing so.
I also tried an alternate method of inserting a curved tube into the filler hole until its far end surfaced above the oil level, to see if this "drain" would allow air to escape fast enough to speed up the oil filling process, but it didn't help unless I used a syringe to actively suck air out while filling the oil pan with oil, and that is a lot more trouble and mess than just doing it the above way.