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JLDHELMS · 10-23-2015, 08:19 AM

I have succeeded in accomplishing every mechanics dreaded nightmare, rounding off the oil drain plug. This problem is on my Onan Gen Set, Model 7.5HDKAJ11451J. To make matters worse, I know better but used vise grips to try a second and third time. Now it is really rounded off. My oil pan material is aluminum.

(1) Can anybody confirm that my plug is a P/N 181-9227, that its specs are 3/8" NPT Plug ( so I can order a valve and never face this again).
(2) Any suggestions as how to extract this SEVERLY damaged plug.
(3) How much heat will my aluminum oil pan get if my last resort is to weld a nut over the steel plug nub with the oil still in the crank case? Danger?

Thanks for any suggestions.
Jim

okcnewbie · 10-23-2015, 01:11 PM

The first thing I would try is to take a dremel or cutoff wheel and make a sturdy slot across the bolt. Then take a custom flat blade ( maybe ground down an old wrench ) Then you can use that to remove the bolt.

I've also had success with the removal tools but you do have to be able to pound on them to get them to seat.

Sears.com ( nut and stud removal set )

dennis45 · 10-23-2015, 01:19 PM

If it were mine, I would weld a nut onto the stub while there is still material to weld to. You will not generate enough heat to damage the Aluminum since it will be cooled by the oil in the pan. Be sure to let it cool sufficiently before you attempt to turn.
If I recall correctly, the thread size on mine is 1/4" NPT.
Good Luck

Old Scout · 10-23-2015, 01:23 PM

Believe the oil plug is brass--pretty soft, as you have already found out. Not sure how the Sears tool listed above might do but think I would attempt to drill a hole an use an extractor tool. The oil pan will help to keep the oil plug in shape as the extractor tool continues to put more and more outward pressure on the hole in the plug--just dont drill all the way thru. If extractor doesnt work, as a last resort, you can drill larger and large holes in the plug until you can collapse the remaining thread wall--be very careful not to nick the threads in the oil pan......be patient--good luck...
PS--I have ecountered this alot with Onan oil plugs--must be a differential thing with the two metals....

Winepress · 10-23-2015, 01:25 PM

Might consider drilling it out in the center of the bolt and use an easyout. That must really be stuck. Sorry for your situation.

Try and live up to your dogs opinion of you.

MSHappyCampers · 10-24-2015, 06:55 AM

Quote:

Originally Posted by Winepress

Might consider drilling it out in the center of the bolt and use an easyout. That must really be stuck. Sorry for your situation.

Try and live up to your dogs opinion of you.

This sounds like the best solution to me! Good luck!

AFChap · 10-24-2015, 09:19 AM

Best solution is a stud extractor. I bought a set at an auto parts store after a service shop ruined my plug ...discovered a year later when I went to change the oil. No drilling involved. You tap the size extractor called for over the rounded plug and turn it out with a socket wrench. I ordered a new plug first, and noted the new plug has a larger head than the original. .."Plug-hex pipe” 502-0153, Cummins Onan, Elkhart IN, 574-262-4611, $2.29, shipping $10.38, TOTAL $12.67

JLDHELMS · 10-24-2015, 03:19 PM

Thanks "okcnewbie". As usual, I get many ideas on this website that lead me to a solution path. Based on the above advice, I think my safest course of action is to cut a slot across the remaining piece of the plug (as deep as I can cut with a Dremel tool) and use an impact driver to drive a straight blade head counterclockwise. If that should shear off one side of the slot, I still have the welding option. My plug is steel, looks like 3/8NPT. Thanks for your ideas. I will report my success hopefully. Jim

FIRE UP · 10-28-2015, 09:23 PM

Quote:

Originally Posted by JLDHELMS

Thanks "okcnewbie". As usual, I get many ideas on this website that lead me to a solution path. Based on the above advice, I think my safest course of action is to cut a slot across the remaining piece of the plug (as deep as I can cut with a Dremel tool) and use an impact driver to drive a straight blade head counterclockwise. If that should shear off one side of the slot, I still have the welding option. My plug is steel, looks like 3/8NPT. Thanks for your ideas. I will report my success hopefully. Jim

JLD,
Good luck on that "straight slot" maneuver. I had a buddy with the same exact generator and, the SAME EXACT PROBLEM recently. He, we, and others used every tool imaginable to remove that stuck plug. AIN'T HAPPENING! So, he drilled it, let the oil run out, then kept drilling larger and larger 'till he was just under the size of the threads. Then used what he needed to remove the remainder of the torchered plug.

It came out actually quite clean. He ran a pipe thread tap into it just for assurances. He used some bent wire with tiny pieces of rag attached to it to clean out any possible filings that might have remained at the exit area of the drain hole.

Then, he simply threaded in a new plug, that purchased at a local auto parts store. There's simply NOTHING fancy about an oil drain plug. You can go to Onan if you like or, head down to your local auto parts store and pick up a new brass or steel one. I'd put some anti-seize on it though, before installing it.
Scott

JLDHELMS · 10-29-2015, 07:14 PM

Thanks Fire Up. I appreciate the details. I have had other advise the drilling process and that is probably the direction I will go when I get back to this project (fell and have a shoulder separation). I've done the drilling before on other projects and the only problem I had was the centering consideration. I like to think of my alternative if what I try fails. I think I will order one of the valves offered for this application and dispense with the plug problem forever. Thanks again for the encouragement.

tmw188 · 10-29-2015, 07:30 PM

Centering can be a real issue especially if you try to keep drilling larger and larger holes. Can you grind a flat spot on the surface first? Take a socket that fits just over the plug so as to keep it centered and then the smallest funnel you can find set it into the socket and use it as a way to center your drill bit and use it as a guide. Good luck!

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mojoracing · 10-29-2015, 08:02 PM

Wow, I hate these problems. Had tons of them over the years and have used all the options mentioned plus a few. The hard part is looking at it and assessing the first method to use so that the second and third still have a chance. LOL. Patience and time. I think I spend more time staring at the problem with my mind whirring until I come up with the right solution than I do actually repairing it. The drill out method works well but even when you get the first hole centered, the follow up holes can go off center. The slot is risky but I've had it work. The slot has to be deep and whatever type of blade you use has to fit extremely snug. I would heat the pan a little as the aluminum will expand quicker than the steel.

KIX · 10-29-2015, 08:18 PM

You may want to suction the oil out using the dip stick tube before you start drilling on the plug, If you get most of it out you will at least limit your oil bath. Good luck.

gfs1943 · 10-29-2015, 08:37 PM

Something I've had work in similar situations: Drill two holes into, but not through, the drain plug -- each about 1/3 of the way in from the edge. Doesn't have to be precise. Tap those holes, with a bottoming tap, for a #10 screw. Insert two screws as tight as you can get them. Lay a large screwdriver horizontally between the screws and try to turn the plug out. You may have success if you try to tighten the plug a bit first, then loosen.

Please keep us posted on what works for you.