Questions on removing stripped rear diff. fill plug with air chisel.

loondog33

Original poster
Member
Jun 25, 2014
84
Good evening everyone,

So I've been doing maintenance on the truck and had planned on changing differential fluids along with replacing trannie filter. First was the front differential, but couldn't budge the bolt even with 18" breaker bar. I moved to the rear differential and noticed the fill plug was stripped already, but I still tried to get it out with 1/2" breaker and 3/8 adapter. No luck. I finished up the trannie filter no problems. I did the transfer case no problem because Grease Monkey, who stripped the rear diff plug, also left the TC plug so loose it was leaking. Will never go to another oil change place like Grease monkey again, I had a darn coupon and thought I was saving 10 bucks.

Here's my questions:

I've read on here and other forums that I can try to use an air chisel to hit rear plug in a counter clockwise direction to break it loose. I understand the concept but I'm curious as to the proper technique. What chisel bit would work best? A narrower flat head or the fattest flathead that will fit in the plug? Any certain air pressure setting to start at, ie. full pressure or turn the pressure down? Should I gently tap the plug's sides or really go at it? I figure I should slowly tap while trying to work it left, as not to damage differential housing. Where to find a new replacement plug, and which metal to get brass, steel or aluminum?

Are harbor freight air hammers and chisels capable to do this job? What are the dangers of trying this method?

I don't have access to any welding equipment nor do I possess any welding skills, so I would have to pay a shop to weld an extension on or do anything like that. Honestly, I'd rather buy a new cover for $159 before paying $ 60-80 to have bolt removed.

Also, would a impact wrench work to get the front differential plug out if my next attempt with breaker bar and longer extension fails? I'm going to try to get better leverage outside the wheel well area with a couple of borrowed longer extensions and my breaker bar, but curious if a pneumatic torque wrench would work or just strip it out. I'll be using a six sided 18mm socket.

Edit:
I've also heard of heating up a bolt and then applying wax to get out a stuck bolt. Could a propane torch heat up rear plug enough to use the wax trick? I really do not want to try getting under truck on ramps and using a torch at all, but if it comes to that I might.
 

loondog33

Original poster
Member
Jun 25, 2014
84
Well I dug around a bit more and found this video on youtube from wolf auto parts:

https://www.youtube.com/watch?v=POkYiizpE0Q

It shows how to remove a stripped hex head. I think I'll run to Farm and Fleet and grab their $15 air hammer and give it a go. Any input is still welcomed. Thanks.
 

DAlastDON

Member
Apr 6, 2014
5,550
Kentucky
ATF and Acetone. It is the best concoction i have ever used on a rusty bolt. Mix some up in a container that is not plastic. About 50/50 ratio. Use that as a penetrating fluid. Got the idea from http://gmtnation.com/forums/topic/11496-what-is-your-favorite-penetrating-oil/?hl=acetone#entry287608 .

I have broken my fair share of bolts on exhaust components. I used this to free up the original header bolts on a 1997 taurus. I was expecting to break at least one and for them to be a pain in the ass. I poured it over the bolts and let it sit ten minutes. The bolts broke free with much less effort then i was expecting to exert. Did not break a single one and finished the job in half the time i guesstimated.
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
How are you going to put a notch in a recessed bolt (the fill plug) and use the same method he did? I don't think that'll work.. That's the only input I have though, sorry. I'd definitely wait a day (for all of the mid-day guys to come around) before buying tools just so you can get as many ideas from the guys here as possible.
 

loondog33

Original poster
Member
Jun 25, 2014
84
Mounce said:
How are you going to put a notch in a recessed bolt (the fill plug) and use the same method he did? I don't think that'll work.. That's the only input I have though, sorry. I'd definitely wait a day (for all of the mid-day guys to come around) before buying tools just so you can get as many ideas from the guys here as possible.
I thought about that after watching video. But I've read post where people suggest hitting to the left with an air chisel, no further instructions. I'm not sure but I think I would just put a notch in one of the walls of the 3/8 recess and chisel there leftwards.

BlazingTrails said:
Why not just loosen the cover to drain it and fill it from the top plug opening?
Do you mean the vent on top of the housing? Because my issue is the fill plug, I can't get it out. No drain plug so I will have to remove the cover to drain fluid for sure. Plus I would have no way to check differential fluid if I filled through the vent.
 

kickass audio

Member
Aug 25, 2012
955
Just to chime in, I don't think using the chisel method will work for your fill plug as is is recessed. It very well could but I can't say I have ever tried to use an impact tool on to hammer recessed plugs free.

Question for you though, when you say it is stripped how bad are we talking about? So bad that when you put a decent amount of torque on it that it will slip out of the plug? Or is it horrible so the point that any torque will make it slip out? If you can get it so it can be torqued on with a decent amount of torque from your breaker bar I would suggest just heating it up with something hotter than propane like an acetylene torch if you can get your hands on one. They burn hotter than propane and it is what you need to get the sucker hot enough to where you can then spray it with some ice cold water and break it free. Trust me, I have done that trick on so many of the seized bolts and fasteners on my truck after my neighbor taught me that. Propane gets it warm but nowhere hot enough for it to fully penetrate into the casting of the axle so it can get the whole hole warm enough for the water to get sucked into the threads. Even if you use MAPP gas that is not hot enough to where you can fully heat the metal on the axle all the way through.

I vote for first getting an acetylene torch whether it be from a buddy or taking it to a local auto shop to help and heating up the area around the plug, do NOT put direct heat on the plug, ONLY the axle where it is around the fill plug! Once they get it so its hot enough give it a few sprays with some very cold water and keep doing that until it stops hissing when the water hits it. Next try to use your breaker bar to get the plug free, be careful as the axle and plug are going to be very hot so do not touch them with your hands and as a precaution wear nice and thick gloves not coated in oil, gas, etc for this. You should be able to get the plug out without damaging the threads unless someone cross threaded it when putting it in.

Should that not work then you can try to get an impact hammer that with the chisel I would use a flat head chisel that is just big enough so you can get the blade of it into the plug. The trick here is to first go at a direct angle and then start to angle the hammer so you will back off the plug. To explain this, you would take the sharp blade of the chisel and position it into the plug so it is facing to the outer edge of the plug where the threads are. (DO NOT put the chisel so it is straight into the middle of the plug! You need to put it so you are going to chisel an indentation into the side wall of the plug, not the center of the plug) Once you have it positioned on the inner side of the plug make it so your impact hammer is in a straight position, do not angle it at all. Next start pulling the trigger on the hammer and keep it on there until you get a nice indentation, do not go all the way through the plug and start to chisel the axle threads! Once you get a nice indentation start to angle your impact hammer so you will be turning it into a counter clockwise position all the while keeping the blade of the chisel in the slot you indented in the plug, You should see the plug slowly spinning counter clockwise as you do this. After a bit of movement you should then be able to get it pulled out with your breaker bar.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I thought mine was stripped, but I tried an impact and there was enough left to grab and the vibration knocked it loose. I also did it after driving so the metal was warm.
 

shrek77

Member
Mar 30, 2012
252
My mechanic tried to get mine off it stripped and was rusted pretty bad. He welded a bolt to it and the bolt broke off close to the base like filling the original drain plug head making it stick out some. He then used the air hammer with a large flat head like bit on it and slowly walked it out.
 

budwich

Member
Jun 16, 2013
2,027
kanata
on my 96 ford, I was able to get enough access to drill a hole into the existing plug ( you have the cover off so you can stop any metal contamination. I then drill a hole large enough to thread a bolt to use as a "second" plug. If you are lucky, you can basically drill out the old plug and clean the threads before replacing with new plug.
 

meerschm

Member
Aug 26, 2012
1,079
you can also purchase a cover with a plug installed, or put a plug in your cover.

or do what I did and sell it.
 

loondog33

Original poster
Member
Jun 25, 2014
84
Well, I could of sworn I read someone's post stating they used a air hammer on the rear diff on the other site. But here I've found the opposite to be more likely.

Here is a quote from Roadie on this topic:

"... I tried those exact nipple extractors, and they chewed up the recess and then started spinning. Then I got uncharacteristically angry and went to town with an air chisel and started doing damage to the aluminum housing. Then I quit."

So if a more seasoned gear head found no success with an air chisel, then I fear I'll fare much worse. Looks like I'll have to cough up dough for either a new PML cover or have a nut welded on the front of rear cover at the fill level.

Anyone know of an aftermarket cover with fill/drain plug for the torson 10 bolt, that's how PML describes my diff cover, that is cheaper than $170? I looked but TA, Dorman and others don't seem to make a cover that fits the trailblazer/envoy. I think the Mag covers are over $200, but I'm looking for one under $100 if possible.

I think since I have to go through this ordeal of cover swapping I might pick up a impact wrench as a last ditch effort, but what kind of ft/lbs would I need to knock this bitch loose if I can actually get a bite on it. 300ft/lbs or more?
 

meerschm

Member
Aug 26, 2012
1,079
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The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Indeed. I destroyed my fill plug, and now my cover has a welded in bung at the proper height for a level check and fill.

Filling the diff through the vent tube is a multi-hour mess of misery, as anybody's who's done it in an emergency knows. I was about to go to my plan B, which was to freeze the proper amount of diff oil in cubes using dry ice, pack them all into the diff, and then slap the cover on before they melted.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
For the removal of the plug, try making your own removal tool, as per this page:
http://mgaguru.com/mgtech/tools/ts204.htm

What you have to be sure is that it is flat on the end so it goes in as deep as possible, with square edges (not rounded like an extension) and exactly 3/8" so it fits tight. Hammer it into the plug. I would use an impact wrench on it first try as the vibrations will help break it free as will the hammer hits.

If all fails, then there are add-on drain plug kits for tranny pans but I believe that the exterior has to be rust free and flat to seal properly. I think a new diff cover and drain plug kit would work.

http://www.summitracing.com/int/search/part-type/drain-plug-kits
 
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loondog33

Original poster
Member
Jun 25, 2014
84
Got my front differential plug out and changed the fluid today. The fluid was dark and smelt like sulfur/rotten eggs. What's weird is I tried breaking the front fill plug loose last week with 2 ft of 1/2" drive ext and a universal ext so I could get at it outside the wheel well. Well I thought the socket slipped off the bolt head when I tried breaking the last time. Being worried I'd strip it out I gave up for the night. I decided I'd have to take the wheel off so I could bungee strap the wrench in a way to keep it from slipping off the bolt head so I could use a 5ft breaker bar to break the bolt loose.

Well I get the darn tire off and as soon as I touched the bolt head with the 18mm socket, the darn thing turned, didn't even get to use the breaker. The plug was dry before I sprayed it with pb.blaster, so no oil was leaking. I guess I must have actually broken the fill plug free last week when I thought the socket just slipped off the bolt head. Either way, I was glad to get the front done, but sad because I kind of wanted to use the 5ft breaker bar as well.

I still gotta get at the rear but still not sure how I'll get it out. Gonna see how much bite is left on it with an ext from harbor freight, harbor freight ext's seem to have much less of a hump on them than my 3/8 wrench or 1/2-3/8 ext does. Hopefully I can still get a bite on it, but I'm not sure how long of a breaker bar I'll be able to fit under there because my 18" isn't cutting it.

If that don't work I guess I'll find a used cover from junk yard and find someone to weld on a bung hole.
 
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loondog33

Original poster
Member
Jun 25, 2014
84
Today must have been my day. First, my front fill plug just came out like butter. Then I decided to give it a go with the rear, so I got a new 1/2 to 3/8 adaptor from harbor freight because it looked less round on the end than my husky ext.

But the adaptor fit loosely, so I decided to go for it with my 3/8 husky ratchet wrench. I first tried a 6" ext with the wrench but it was loose as well, so I just stuck the 3/8 wrench in the hole. Low and behold the 3/8 husky wrench fit it nice and snug. Actually so snug I couldn't pull the wrench out easily once in place. Since I had a good bite, I lightly tapped wrench with a hammer but quickly decided to grab my jack handle to use as a breaker bar, and BAM! The plug finally cracked. Also, I soaked the plug with PB blaster before running to harbor freight and again right before trying to go at the plug. If I would have kept trying with the 1/2 to 3/8 adaptor and my breaker bar I would have never gotten that plug out!

Now I can run grab two quarts of oil and hit the rear differential in the morning. One less thing to worry about.
 

loondog33

Original poster
Member
Jun 25, 2014
84
Thanks. After seeing how nasty my front diff. oil was, I had to get that rear plug out one way or the other. It's nice not having to go to a shop over a darn fill plug. :thumbsup:
 
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loondog33

Original poster
Member
Jun 25, 2014
84
Mounce said:
Yeah that woulda sucked! Are you gonna put a new plug in it since this one is messed up a little?
That's what I want to do but I don't know if I'll be able to find a suitable replacement.

I read one thread where a fellow said he scored a new brass plug at oreilly's so I think I'll start there. But I think the amount of bite I can get with my wrench, I should be good as long as I check oil every month or so until I find a suitable replacement.
 

loondog33

Original poster
Member
Jun 25, 2014
84
Well I did the rear diff. today. The fluid was black and there was a layer of metal mud on the magnet, not to happy to see that. Hopefully it's not a big deal. There were no metal chunks or shards, just a lot of stuff on magnet. I can see why people on the forum are so adamant about fluid changes ie. transfer and differentials.

I didn't end up finding a new plug but I have enough of a bite left with my 3/8 wrench I should be good to go next time.
 

kkeo211

Member
Apr 14, 2014
87
Glad to hear you go the bolt out. I had the same issue with my rear diff, I even put my SnapOn 18v impact on it and it didn't budge. I finally put a 18" breaker bar on it, and it came out.
 
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