Differential Plug Stuck, Stripped

Joined
Nov 20, 2006
Messages
26,683
Location
MA, Mittelfranken.de
I think what Trav and others are saying is that if the diff cover bolts break off then you have to get those out and it's a bigger mess. You are already having issues accessing the drain plug and without welder etc, you may get into larger problems.

What are you comfortable with? Maybe it's best to get the new cover and drain bolts and get a shop to remove the old stuff and install the new and make sure they put antisieze etc on the new ones and don't over torque anything.
In the salt belt aluminum parts under the car can sometimes be trouble when it comes to corroded fasteners. When I do a job like this I always figure in my head what will I have to do if this or that happens, I always have a plan for the worst case scenario.
In this case it would be a bolt broken I cant get a drill into because it is obstructed. These would probably be the upper cover bolts and those are the ones I break loose first, If one snaps it can still be driven to a place with a lift.
 
Joined
May 30, 2010
Messages
13,656
Location
North Carolina
It's probably a 5 minute fix with one of these.
IMG_20201108_154031226.jpg
 

Chuck61

Thread starter
Joined
Jan 5, 2021
Messages
34
So I figured that I’d just buy a new cover and gasket at this point, and go that route. But the rear Diff cover on Subarus has mounting bolts that go through the crossmember, which means I’d have to drop the diff a bit to remove the cover, which could be a huge pita. So I figured I’d give it a go the old fashioned way one more time.
I put it up on stands this time, for more clearance. I’d been hitting it with liquid wrench for a week. Maybe it would help? I was able to get a much better swing with a hammer to drive the hex bit into the plug, and I was surprised at how much further it went in than the first time. This was part of the problem the first time, I’m sure.
Threw the breaker on the bit, gave it a few max effort pushes, and it started to go-very slowly at first. Gave it a few more pushes to get it to move just a little, but it finally broke! At that point I was able to spin it out with my fingers. Success!!! I did the drain plug same as the fill, and it broke much easier, like bolts usually do. I’m not sure why the drain broke much easier than the fill, but I have a couple of theories. First, maybe it’s because the hex insert on the drain plug wasn’t rounded like the fill, and allowed a lot more force to transfer. Or maybe because the drain plug is always surrounded by oil, preventing corrosion, while the fill isn’t. Maybe the liquid wrench helped?
Whatever the reason, I’m glad it’s over! I’m pretty strong, and it took everything I had to get that **** fill plug out. Picked up some anti seize for the reinstall, and a new (external head) fill plug. Kept the drain plug because it wasn’t rounded, it actually came loose like a normal plug, and it’s magnetic to colllect debris metal (which there was plenty of).
 

Chuck61

Thread starter
Joined
Jan 5, 2021
Messages
34
It's probably a 5 minute fix with one of these.
View attachment 40787
Probably would’ve been, with much less day-after shoulder pain. I bought screw extractors, a propane torch, a can of liquid wrench, some anti-seize, some socket adapters, and I’m sure more that I can’t think of, for what should’ve been a simple job. At least I have that stuff now. I’ll save the welder for the next mishap🤪
 

Chuck61

Thread starter
Joined
Jan 5, 2021
Messages
34
Glad you got it out.

FWIW, Ive found WD4o to be a terrible penetrating oil. My personal preference is PB Blaster.

Agree, shock from the hammer was probably a factor...
Hadn’t really considered the hammer blows, but yeah, those probably helped quite a bit.
 

JC1

Joined
Nov 29, 2008
Messages
6,391
Location
Oshawa, Ontario Canada
I'm glad you got it done. Kudos to you.

Persistence and determination are key factors. I've been there many times and some times it's good to take a brake from the garage watch a few videos and chat to the folks on here while you collect your thoughts and regroup.

Did you take any pics of the open diff and the damaged bolts?
 
Joined
Nov 13, 2020
Messages
218
I'm glad somebody's having success working on their old stuff. I rounded off the drain plug of my GM 4L60E transmission and haven't figured out a way to get it off yet.
 
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