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1G I Stripped the transmission drain plug

SnowmanFD

Proven Member
136
7
Dec 11, 2021
North Seattle, Washington
I Stripped the drain plug to my transmission like an idiot. Any ideas on how to get it out?

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curt-s

Proven Member
1,547
312
Dec 21, 2008
Winnipeg, MB_Canada
you could always try to cut new facets with a dremel and cutoff wheel, make it a smaller one. but that would be crazy.
sometimes you can just pound a socket onto it but it would have to have little to no taper given how shallow the bolt heads are.
 

luv2rallye

DSM Wiseman
8,303
1,094
Jun 7, 2003
Minneapolis, Minnesota
Happened to me. I put a 6 point socket on and braced the socket/wrench with a block of wood and crow bar forcing it (a lot of force) to stay on while turning (filler plug has same problem: https://www.dsmtuners.com/threads/transmission-help.488183/#post-153482868). After this happened to me multiple times I finally put a normal bolt in with a normal head on it (no taper or shallow bolt heads like the original plug has). {Plug specs: https://www.dsmtuners.com/threads/n...in-and-fill-plug-sizes.532142/#post-153785818}.

Or try this one (although I like and have the cheaper Harbor Freight Pittsburg Pro one even though the largest socket is only 19mm {https://www.harborfreight.com/38-in-drive-metric-bolt-extractor-socket-set-9-pc-67894.html}) :
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Or last resort (although I wouldn't heat up the aluminum tranny case method):
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Last edited:

SnowmanFD

Proven Member
136
7
Dec 11, 2021
North Seattle, Washington
funny enough I had just finished fighting a stuck fill bolt, come to find out the drain bolt is also stuck. the bolts came off surprisingly easy on the diff and transfer case but idk why the diff bolts are so dam harm

Happened to me. I put a 6 point socket on and braced the socket/wrench with a block of wood and crow bar forcing it (a lot of force) to stay on while turning (filler plug has same problem: https://www.dsmtuners.com/threads/transmission-help.488183/#post-153482868). After this happened to me multiple times I finally put a normal bolt in with a normal head on it (no taper or shallow the bolt heads like the original plug has). {Plug specs: https://www.dsmtuners.com/threads/n...in-and-fill-plug-sizes.532142/#post-153785818}.

Or try this (my favorite works really well - note Harbor Freight has a cheaper Pittsburg Pro one) :
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Or last resort (although I wouldn't heat up the aluminum tranny case method):
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MD728088
is this something i could buy/use a universal bolt from Oriley's?
 

Mech Addict

Supporting Member
989
427
Jun 9, 2019
Jackson, Wyoming
Normally a pipe wrench would be in order, but that skinny head gives no purchase, and virtually no easy access anyway. Do you have access to a welder? I would weld a slightly smaller but regular height nut onto that plug, and try that. Be careful not to overheat the aluminum case.
Otherwise they do make special gripping extractors, although again, such small corners to grab. Ultimately you might have to start drilling it out for an internal extractor. That might get metal shavings in the trans, though a magnet would like work for getting them all out.
Good luck.

Looking at the photo one more thing comes to mind: grind off the cast aluminum “eyebrow” that obstructs the side of the plug. Would make it easier to get an open-end wrench from the side.
Main point: why did they make these so low-profile!!?!??
 

waltah

Proven Member
369
153
Mar 2, 2011
fairfield, Virginia
Some very good ideas here. Some more to think about, in the order I'd try them:

1. Smack the face of the plug a time or two with a hammer -- not hard enough to damage the transmission case. Get a 6 point socket, grind the face square so you don't have a bevel eating up your working surface and grind the outside diameter slightly if necessary to fit all the way down on that plug.

(As a rule of thumb don't use 12 point tools except on Mitsubishi head bolts which are designed for them or in the few situations where a 12 point box is your only choice. 12 point are fast but they damage fasteners that are now sometimes almost unobtainium.)

2. Use about a 1/4" drift and a ball peen hammer whacking the plug 'in' near the edge. You don't want to flatten it any, just break the stiction of the threads/flange all the way around. Move the place you hit CCW so that you encourage it to unscrew. Do maybe 6 places around the edge, go around a couple of times. Then try your 6 point socket again.

This is a more pursuasive version of #1 and will almost always work for a plug in aluminum but not so reliable in cast iron.

3. Use a cold chisel at an angle and hit hard enough to raise a chip a half dozen or more places around the edge, driving in the 'unscrew' direction. This too is a pretty powerful technique but you'll likely need to replace the plug afterward.

4. Get a left hand twist drill and drill the center of the plug. Drill a small pilot hole mostly through then go with one that's maybe 3/4 the diameter of the plug threads -- you don't want to hit those threads. Left hand drills because often the drill winds up just backing the screw/plug out and you are done.

If the drill didn't take the plug out, go at it with the 'easy out' Use one of the square ones that cut into the plug, not the spiral kind that wedge -- I have never been able to make the spiral ones work.

If the eazy out doesn't do it, take a hacksaw blade that'll fit the hole (grind the back if necessary), wrap one end with tape to protect your hand, then cut slots from the inside out, but not deep enough to damage the threads in the case. Cut 4-5 of them along one half of the circumference. Use your drift or a cold chisel from the side at the middle of your cuts to collapse the remainder of the plug out of the hole. Once it starts to loosen you can unscrew it with needlenose pliers.

There are self-tapping oversize drain plugs for many applications. Also I think there are heli-coil type inserts where you use a special tap, screw in an insert, and you have new threads fitting the original plug.

I'll bet these near flush drain plugs are a defense against a road hazard smacking your drain plug out and spilling transmission fluid or oil back on your cat/exhaust pipe.
 
Last edited:

danl

Proven Member
683
93
Apr 8, 2002
Severn, Maryland
Some very good ideas here. Some more to think about, in the order I'd try them:

1. Smack the face of the plug a time or two with a hammer -- not hard enough to damage the transmission case. Get a 6 point socket, grind the face square so you don't have a bevel eating up your working surface and grind the outside diameter slightly if necessary to fit all the way down on that plug.

(As a rule of thumb don't use 12 point tools except on Mitsubishi head bolts which are designed for them or in the few situations where a 12 point box is your only choice. 12 point are fast but they damage fasteners that are now sometimes almost unobtainium.)

2. Use about a 1/4" drift and a ball peen hammer whacking the plug 'in' near the edge. You don't want to flatten it any, just break the stiction of the threads/flange all the way around. Move the place you hit CCW so that you encourage it to unscrew. Do maybe 6 places around the edge, go around a couple of times. Then try your 6 point socket again.

This is a more pursuasive version of #1 and will almost always work for a plug in aluminum but not so reliable in cast iron.

3. Use a cold chisel at an angle and hit hard enough to raise a chip a half dozen or more places around the edge, driving in the 'unscrew' direction. This too is a pretty powerful technique but you'll likely need to replace the plug afterward.

4. Get a left hand twist drill and drill the center of the plug. Drill a small pilot hole mostly through then go with one that's maybe 3/4 the diameter of the plug threads -- you don't want to hit those threads. Left hand drills because often the drill winds up just backing the screw/plug out and you are done.

If the drill didn't take the plug out, go at it with the 'easy out' Use one of the square ones that cut into the plug, not the spiral kind that wedge -- I have never been able to make the spiral ones work.

If the eazy out doesn't do it, take a hacksaw blade that'll fit the hole (grind the back if necessary), wrap one end with tape to protect your hand, then cut slots from the inside out, but not deep enough to damage the threads in the case. Cut 4-5 of them along one half of the circumference. Use your drift or a cold chisel from the side at the middle of your cuts to collapse the remainder of the plug out of the hole. Once it starts to loosen you can unscrew it with needlenose pliers.

There are self-tapping oversize drain plugs for many applications. Also I think there are heli-coil type inserts where you use a special tap, screw in an insert, and you have new threads fitting the original plug.

I'll bet these near flush drain plugs are a defense against a road hazard smacking your drain plug out and spilling transmission fluid or oil back on your cat/exhaust pipe.
This is the methods and order in which I use them. I’ve never really had any problems, but I use only one socket in particular for these drain plugs. It’s is both uniquely low profile and 1/2” drive, allowing me to provide good pressure and good alignment when breaking free. I’m not sure if it matters but it is standard size, which may be slightly tighter fitting.
 

waltah

Proven Member
369
153
Mar 2, 2011
fairfield, Virginia
This is the methods and order in which I use them. I’ve never really had any problems, but I use only one socket in particular for these drain plugs. It’s is both uniquely low profile and 1/2” drive, allowing me to provide good pressure and good alignment when breaking free. I’m not sure if it matters but it is standard size, which may be slightly tighter fitting.
Ding-ding-ding! Low profile is good because it's not so easy to tip it off the plug.

I'll add that to the mental toolkit. Just slice that sucker down to about 1/4" deep with a cut off wheel and square it up if necessary. Also if the socket is never used for anything else it gets no wear so will always fit like new.

Yeah it's rarely a problem because there just aren't that many drain plugs on my cars that I'd let anyone else touch.
 

waltah

Proven Member
369
153
Mar 2, 2011
fairfield, Virginia
Tack weld a 17mm nut on it. You're welcome!
This is excellent with three footnotes:
1. Unless you then replace the plug you've raised the profile making it more subject to being knocked out by road junk -- possibly spectacular (fire) if it happens at speed so hot oil sprays back on your exhaust.

Remember the warnings about grass fires caused by catalytic converters?

2. The temperature in the arc while welding is way above the melting point of aluminum. If it's done by someone who knows exactly what he's doing the too-hot area won't spread enough to cause trouble. So ... how well do you know your welder guy?

On the other hand ...

3. The extreme heat will almost always break the frozen plug loose due to differential expansion, especially if it's rusted/corroded in place.
 
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