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Dorman oversized drain plug

For those that have used Dorman self-taping oversized drain plugs (or other brand) on stripped threads on Aluminum drain pans like bottom of Allison tranny or M11 engine, are the oversize plugs a permanent solution ?

I also see there are double-oversized drain plugs and drain plugs with a 2nd center hole for draining.

I have never used these and they seem like they could be an alternative to drill/ream & tap with an new larger drain plug.

Re: Dorman oversized drain plug

Reply #1 –
I recently did the "drill and tap" on my M11.  Serious job, but completely successful.

I would be worried that a self-tap might tear out threads beyond the size acceptable for a proper repair.

I would use an expanding plug for longer term, IF I could wire it in place with safety wire.
Matt B
1998 u-320

Re: Dorman oversized drain plug

Reply #2 –
So yes they are sold as a fix, and they probably will work, but I would personally prefer to tap with the proper tap. In the ism I would go to a coarser thread. I couldn't be leave how tight mine was at removal 1st time and it's been in the back of my mind since I last installed and torqued up. I hope to never remove the quick drain.
Scott

Re: Dorman oversized drain plug

Reply #3 –
One small item I learned from the Allison shop in Longview is the drain plug comes in two different lengths for the transmission. The longer one utilizes all the threads in the pan. I changed to the longer one.... Don't know the exact length but appeared to be about 3/4 inch longer.
The selected media item is not currently available.
Lynn & Marilyn Sickel
Tollville, AR
1997  U320  40'
2021 Chevrolet Silverado pickup
Motorcader  17257

Re: Dorman oversized drain plug

Reply #4 –
I haven't run into stripped threads in the Allison drain plugs.

May be because it is removed on such infrequent intervals, or that people actually read the torque specs on the instruction sheet that comes with the filter kit.

Yes, engine oil changes by BUBBA can certainly strip the drain plug in aluminum pan engines.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Dorman oversized drain plug

Reply #5 –
A tip -

If your M-11 oil plug has a seep, just let it seep until you are ready to get serious about it.

Our plug had a three-a-week persistent drip.  I put a wrench to it, and it did not change.  Second time, months later, it kept spinning!  Uh-oh!

It would be my nature to give it a snug in a campground, Walmart parking lot, etc.  That could have been catastrophic.  Tell the host you just dumped 11-gallons of oil on the ground, UNDER your disabled coach.  Tell your insurance company you broke the RV.  Tell the shady-looking shop down the street shop you were dumb.  Tell your spouse you just changed an at-home $50 repair into a $2K, stay in a hotel, take a chance on an unknown shop debacle.

I was at home.  One of the millions of blessings I have received,
Matt B
1998 u-320

Re: Dorman oversized drain plug

Reply #6 –
Old Matt hits it exactly on the head. If you have an aluminum oil pan, put in a quick drain. The part number should be posted and also put in the media section. The really good aluminum pans are threaded in at least an inch and have a projection on the plug so it's difficult to damage anything by cross threading.

Matt just missed one thing. The shop mechanic that changes oil on an aluminum oil pan tightens the plug up feeling the torque with his many years of experience but just as it seems almost tight, it gets easier. No need to bring this to the owner's attention, especially if he/she is from out of town and certainly no need to tell the boss.

Pierce

Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Dorman oversized drain plug

Reply #7 –
Quote from: Pierce & Gaylie Stewart –
Old Matt hits it exactly on the head. If you have an aluminum oil pan, put in a quick drain. The part number should be posted and also put in the media section. The really good aluminum pans are threaded in at least an inch and have a projection on the plug so it's difficult to damage anything by cross threading.

Matt just missed one thing. The shop mechanic that changes oil on an aluminum oil pan tightens the plug up feeling the torque with his many years of experience but just as it seems almost tight, it gets easier. No need to bring this to the owner's attention, especially if he/she is from out of town and certainly no need to tell the boss.

Pierce


I am confident that this same mechanic you know of worked on our coach.  The POs were delightful people, very honest, and not the type to be changing their own oil.

I guess honesty would be the sign of the "keeper" mechanic.  "I over-torqued and stripped your oil pan.  I have already ordered the parts, That and the labor are on me, and we will get it back to you priority-quickly."

BTW  I did a write-up of my repair.  It is around the forum somewhere.
Matt B
1998 u-320
 

Re: Dorman oversized drain plug

Reply #8 –
I have changed oil many times over the years of working in dealerships and had never had any until about 2 years ago when I took the drain plug out of an m11 and as I took it out there were pieces of thread. When I screwed it back in just to check it found that the plug just would spin. I did the same repair as oldmat
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins