Differential Plug Stuck, Stripped

[AutoMechanic]

Take the cover off and drill it out then rethread it or get a new cover. Eventually when you drill it out as it gets bigger the sides will just bust and it will all fall out. Get a new plug and maybe a new cover and do it that way.

 

[Chuck61]

Rock auto may have one. Anyway, yes to the propane, let cool and spray it with liquid wrench. Put some vise grips on it. Hate to ask you but are your turning it to the left? I've seen guys get confused when they are lying on their side underneath the car. Also, do you have a pic?

No pics as of now, I’ll try to take some tomorrow. I was turning to the left, that much I am sure of. As for vise grips, it’s an internal hex drive bolt, so there really isn’t anything to grab on to. People keep suggesting propane so I may have to look into that.

 

[TurboTravis]

Inspect the OD of the plug to determine the correct size NPT plug to use and drill/tap thru the center of the existing plug with greased bits/taps (in an effort to collect shavings), thus creating a new plug. Any shavings that may be left behind aren't going to hurt anything, however I would do a fill/drain with a low viscosity oil to help remove them for peace of mind.

 

[Chuck61]

Inspect the OD of the plug to determine the correct size NPT plug to use and drill/tap thru the center of the existing plug with greased bits/taps (in an effort to collect shavings), thus creating a new plug. Any shavings that may be left behind aren't going to hurt anything, however I would do a fill/drain with a low viscosity oil to help remove them for peace of mind.

This is an interesting idea.if I were to do this, would I use a liquid gasket product to seal the plug? Or is that not really necessary on a fill plug?
I picked up some bolt extractors today to try it that way, but in an effort to save time (and make the wife happy) I’m going to swing by the shop tomorrow to see if they’ll break them loose for me. If not, I’m going to try applying some heat and letting it cool a few times, and then take the bolt extractor to it. If that doesn’t work, I’ll either try tapping a new plug hole, or take the cover off and get them loose in my workshop,

 

[RyanY]

Just a thought...does the 10mm hex or Torx bit fit all the way into the bolt head? If not, try a 9mm or 3/8” bit.

My Cadillac diff bolt calls for a 10mm bit, but it is too big and only goes in about 1/4", stripping the head when I turn it. A 3/8" hex fits perfectly and inserts all the way, allowing me to easily get enough grip to remove it.

 

[Greasymechtech]

When there is no problem with clearance, I replace 'allen' head bolts with normal ones.

Verify thread.... M18x1.5????
https://drainplugmagnets.com/cars/subaru/
https://goldplug.com/shop/
https://www.powerslutracing.com/c-1071480-magnetic-drain-plugs-by-thread-size.html

https://www.irwin.com/tools/screw-b...screw-extractors-532-series-plastic-case-sets
Multi spline screw simply screws in and grabs, then lefty loosey and I've never need to drill it out, as I recommended earlier. Just use the biggest one that screws in. If it slips, step up to the next size.

Problem with 'external' grabbing extractors is that the extractor socket will push into the pan cover and might not get enough of a grip. As it slips, it moves forward into pan, transmission cover, differential cover..... Needs to be a pretty good match and works better on thicker nuts/boltheads and not rounds.

Both internal/external Irwin sets have served me for years. Never needed torches.

For 10mm Allen/hexhead drain bolts, only use genuine Allen wrenches or quality hexhead sockets(like snap-on etc). I find the Asian generics/lesser brands strip every time.

And, brute force doesn't work. Invest in impact wrenches. Breaker bars break/strip. Vibration loosens.

An HF 3/8" wrench would've knocked it out easily.
https://www.harborfreight.com/12v-m...s-xtreme-torque-ratchet-wrench-kit-64196.html

If not, the 1/2" would definitely.
https://www.harborfreight.com/20v-m...ss-xtreme-torque-impact-wrench-kit-64195.html

Obviously, you can use whatever brand 3/8" or 1/2" impact driver/wrench that you want... Ryobi, Milwauki, Dewalt, Kobalt... I find them priceless.
Torque the new drain plugs with new washers.

 

[Number_35]

OP, good job trying to loosen the fill plug first!

Whichever route you go, as others have said, consider using a bit of anti-seize compound on the new plug.

There are lots of good ideas here, any number which should work.

 

[meep]

I did the rear diff on my 97 legacy years ago. It was clean and in mint condition. I recall both of those plugs being on there as tight as balls! I couldn’t muster the strength by hand, and ended up raising the car with the jack, positioning a block beneath the wrench handle, and then lowering the jack to use the vehicles weight to do the work. It didn’t “break“ free... but took half a dozen repetitions (maybe 1 full turn?) to ease it enough that I could finish it. There’s lots of good ideas about notches, chisels and heat, but with what I went through before, I like the new cover route the best, especially at that price. hang the old one on the wall.

 

[Chuck61]

When there is no problem with clearance, I replace 'allen' head bolts with normal ones.

Verify thread.... M18x1.5????
https://drainplugmagnets.com/cars/subaru/
https://goldplug.com/shop/
https://www.powerslutracing.com/c-1071480-magnetic-drain-plugs-by-thread-size.html

https://www.irwin.com/tools/screw-b...screw-extractors-532-series-plastic-case-sets
Multi spline screw simply screws in and grabs, then lefty loosey and I've never need to drill it out, as I recommended earlier. Just use the biggest one that screws in. If it slips, step up to the next size.

Problem with 'external' grabbing extractors is that the extractor socket will push into the pan cover and might not get enough of a grip. As it slips, it moves forward into pan, transmission cover, differential cover..... Needs to be a pretty good match and works better on thicker nuts/boltheads and not rounds.

Both internal/external Irwin sets have served me for years. Never needed torches.

For 10mm Allen/hexhead drain bolts, only use genuine Allen wrenches or quality hexhead sockets(like snap-on etc). I find the Asian generics/lesser brands strip every time.

And, brute force doesn't work. Invest in impact wrenches. Breaker bars break/strip. Vibration loosens.

An HF 3/8" wrench would've knocked it out easily.
https://www.harborfreight.com/12v-m...s-xtreme-torque-ratchet-wrench-kit-64196.html

If not, the 1/2" would definitely.
https://www.harborfreight.com/20v-m...ss-xtreme-torque-impact-wrench-kit-64195.html

Obviously, you can use whatever brand 3/8" or 1/2" impact driver/wrench that you want... Ryobi, Milwauki, Dewalt, Kobalt... I find them priceless.
Torque the new drain plugs with new washers.

Would an impact driver with the hex bit do it? That I have.

 

[Greasymechtech]

As long as the hex bit is quality. The drainplug should've been torqued to hopefully extensions needed to reach it. Its worth a try with the tools and penetrating oil you already have.

Specialist. Penetro, or Kroil worth keeping on the shelf:
https://www.wd40.com/products/penetrating-oil/
http://www.kanolabs.com/penLub.html
https://www.schaefferoil.com/penetro.html

Diy'r rule of thumb is to spray all drainplugs a couple times prior to the intended service, like a week, a day, and then just before you service them. PBblaster/Liquidwrench/.... work well enough too.

For 10mm hex, I use either a genuine Allen L-shaped wrench or a Snap-on socket. Other quality name brand tools will work well. I've stripped/broken enough drainplugs and sockets and limit some tools within certain brands. No chicom generics for that 10mm hex!!!!

 

[TurboTravis]

This is an interesting idea.if I were to do this, would I use a liquid gasket product to seal the plug? Or is that not really necessary on a fill plug?
I picked up some bolt extractors today to try it that way, but in an effort to save time (and make the wife happy) I’m going to swing by the shop tomorrow to see if they’ll break them loose for me. If not, I’m going to try applying some heat and letting it cool a few times, and then take the bolt extractor to it. If that doesn’t work, I’ll either try tapping a new plug hole, or take the cover off and get them loose in my workshop,

I would use this product or something similar (many brands make something basically identical) https://www.amazon.com/Permatex-80631-Thread-Sealant-PTFE/dp/B000BKEBT0

 

[Chuck61]

So I’ve decided to got the patient route for now. Picked up some liquid wrench and I spray that on there a couple of times a day. I also picked up a heat gun at harbor freight and I’ll try hitting the plugs with that a few times over over the next few days. Then I’ll see if I can use the bolt extractors I picked up to get it out. Here are some pics of the plug.

 

[AutoMechanic]

If heat doesn’t work try freezing it off or out. Hopefully the bolt extractors will work. Usually I end up rounding off the hex bit instead of the plug lol .

 

[Rand]

hammer in a slightly oversize bit?

my first change on my 2011 it wouldnt budge with me hanging on the 25" breaker bar.
ended up putting a floor jack under the breaker bar and lifting.. that got it ;p

Next one(2015) I had a recently broken shattered wrist so i decided to use the impact wrench on it
(bad idea being aluminum) but it worked.. so no harm done.

note: thats from memory.. one of them might have been the 2013 outback.. but both were subaru.

Footnote: wrist is back to ~~ 80%+ after almost 5 years.. pretty amazing really.. being in 7 pieces.

 

[spasm3]

Probably need a propane torch. Heat it good and try while it's hot in case there is a threadlocker there.
As wide as the flange on the head is, I doubt much penetrant is getting to the threads.

 

[Chuck61]

If heat doesn’t work try freezing it off or out. Hopefully the bolt extractors will work. Usually I end up rounding off the hex bit instead of the plug lol .

I figured the 20 degree weather we’ve been having at nights would do the job, but apparently not.

 

[Chuck61]

hammer in a slightly oversize bit?

my first change on my 2011 it wouldnt budge with me hanging on the 25" breaker bar.
ended up putting a floor jack under the breaker bar and lifting.. that got it ;p

Next one(2015) I had a recently broken shattered wrist so i decided to use the impact wrench on it
(bad idea being aluminum) but it worked.. so no harm done.

note: thats from memory.. one of them might have been the 2013 outback.. but both were subaru.

Footnote: wrist is back to ~~ 80%+ after almost 5 years.. pretty amazing really.. being in 7 pieces.

I’m glad the wrist is feeling good. Sounds like a heck of a journey.

I would like to hammer in an oversize bit but the chassis is in the way and I really can’t get a good swing on the fill plug, especially laying on the ground.
If I can get it out, I’m not even messing around with the drain plug. I’m throwing the breaker bar on and putting the floor jack under it right away, and try to get it off that way.

 

[Chuck61]

Probably need a propane torch. Heat it good and try while it's hot in case there is a threadlocker there.
As wide as the flange on the head is, I doubt much penetrant is getting to the threads.

Yeah, I’m not sure how much of the liquid wrench is getting in there. Probably not much. But it couldn’t hurt, I guess.
Would you recommend drilling into the plug while it’s hot? I have a little butane torch that probably isn’t as hot as a proper propane torch. Would that do the job?

 

[AutoMechanic]

I figured the 20 degree weather we’ve been having at nights would do the job, but apparently not.

They make a spray called Freeze Off made by CRC it’s good stuff lol.

 

[spasm3]

Yeah, I’m not sure how much of the liquid wrench is getting in there. Probably not much. But it couldn’t hurt, I guess.
Would you recommend drilling into the plug while it’s hot? I have a little butane torch that probably isn’t as hot as a proper propane torch. Would that do the joi would

I would try the torch. I would try cutting a slot at the 3:00 position and use a hammer and chisel before drilling. See I'd you can get it to rotate that way. While hot is even better. Last resort would be drilling the center , tapping in a splined extractor and attempting to remove the plug. Doing that would still mean you need to remove the cover to get any drill fragments out.