I don’t know about that specific transmission, but some drain and fill plugs are Allen key and not square. Usually heat will break them loose. If not, try heating the surrounding area and then use a squirt bottle to spray the plug itself. That cools and contracts the plug faster than the surrounding metal.
for the diff, I’d just grab a inexpensive aftermarket cover with a fill plug in it. If you weld or know someone, you can weld some flat stock to a new cover and then tap it for 1/2” NPT and put a pipe plug in it. The stock covers are too thin to be tapped. Summit Racing sells pre fab weld in drain bungs if you want to go that route.

 

Thx ! I'll double check the inside of the plug with a flashlight. My Olde eyes ain't near a sharp as they once were... And heating the housing & cooling the plug is a great tip. I may end up buying a new cover with a fill plug. Thx, again !

 

I have hammered impact rated torx heads into Allen/square fittings to get them out. Sometimes you can re-use but may be good time to scout out local junk yards to see if you can grab some spares. You learned the lesson many of us did. Make sure you can refill before you can drain....

You can always stack a couple of washer and a nut and jbweld/weld it to an equal height part on the rear dif cover. I swore 4wheel parts sold dif covers for like $99 for our trucks with drain and fill ports built in but i have to find the link.

 

It should be a 3/8" square. Someone could put in a hex pipe plug. I've found those to be a 3/8" fitting needing a 1/2" wrenches leverage. Rust can cause the square to be non-receptive, and you don't get full depth on the square. A small screwdriver acting like a chisel and a Dremmel end wire brush may get you some depth to retry if it's square. I never understand why people get randy on a pipe plug. I've got some big ones like that on my dozer, which are needed to come out so I can replace the brake bands.

I've often found the aftermarket rear covers with fill ports overfill the differentials.

The worst-case situation is to drill out the plug, smaller than the smallest taper thread. Then use an air saw to section the remains carefully, and you can punch the segments to the center.

 

G2 Axle and Gear has a rear cover with fill and drain ports for under $150. Check if one is available for your axle. They do have Sterling 10.25/ 10.5 for sure. If the fill plug is too high, just put in the specified amount and don't fill to the plug.

 

Thats the one a couple of my friends run and Im probably gonna get it. No issues in 100k+ miles with same rear seal/bearings, etc/

 

Lots of good info ! I did find a cover with the fill plug online. Going to try some more heat, an Allen head or large torx bit before buying the new cover. Thx !!!

 

I've been using the G2 cover for about 2 years now, it's good quality and holds a bit more oil than stock. There is also a 1/8 NPT port for temperature monitoring if you choose to install. The best part is you never have to muck with the stock gasket or use RTV ever again, it seals with a rubber oring and has it's own drain port too. As for why your fill plug is stuck, somebody else probably hammered down on it. I always check the fill can be loosened prior to draining the fluid, for that very reason you have just experienced.

 

I'm ordering a G2 cover. The axle needed new fluid and I just spaced on checking the fill plug first. Fortunately, I don't need the truck for a few days. The cover should be here by then. I'm guessing the plug is pipe thread, so it's easy to over tighten those tapered threads.... Again, Thx for all the info !!!

 

I just put a g2 on a month ago great product, plus it’s made in the USA.


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not pulling your cover to change fluid is less than ideal IMO the diff has a ring gear pocket that is a prime area for sediment to build up and large chunks to land

 

You got a point there. I did notice there was a decent bit of oil in the pit. It was dirty but not horrible. Drain on the cover or not, I always use a Lube Locker gasket. Easy of. Easy on. No RTV goop.

 

The muck pit.

 

I did clean out the "muck pit". Didn't find any metal, something to consider... However, I'm not going to spend much more time & effort removing that plug... I can always remove the G2 to drain the diff. & will probably change the fluid more often with an easy drain plug with the G2. THX

 

It is annoying that the use of a little antisieze & a little past "finger tight" on a fill plug is all that's needed. It's not as if they're going to come loose. Not to mention the over use of road salts and other diabolical rusting agents used on many of our Northern roadways.

I miss the days of studded snow tires... Blizzaks help. However, nothing beats studded tires on ice & chains in snow.

And I don't care about wearing down the highway... The cheap asphalt they use around here only lasts about 5 years before it starts going bad and needs re-done.... Rant over... for now. SMILE !

 

The much is all the iron wear particles. It's down there or on the tone wheel sensor for those trucks that have them. I believe the factory fill plugs have the sealer on the surface, too; they don't have to be that tight. The only time I've found them missing is after a tech has worked on a rear axle and the plug is left sitting on a cart or the back post of the in-ground twin post lift.

 

then again the service interval of a DIF is a lot of miles so pulling the cover every 6 years or more is no biggie lol

 

Diff plug update. I crawled back under the truck a few days ago. Took a flashlight & a screwdriver to clean out the inside of that stubborn fill plug. 3/8" square. Took the torch to heat up the case. Sprayed some cold water inside the plug. Tapped a new 3/8" impact extension into it. Applied ample pressure to said plug via long breaker bar. Hallelujah ! Eureka ! The plug is turning !!! Oh.... wait ... Nope... Just finished completely stripping it out ... Waiting for the G2 Axle & Gear cover to arrive.

Thx again for all the great info ! 7.3 Boomer

 

lol

 

haha, been there, done that.

 

 

Lol. Nice.
I'd do an eyeball test to see, but filling to the upper fill hole in the new cover looks close to factory level. Could just put the specified amount in if you cleaned out the pit and call it good. Helical gears aren't picky. Glad you got it back together!

 

First real road test this evening after doing the oil cooler seals and allowing the RTV to cure for 24 hours on the differential. First time in years with no leaks of any kind. Crawled under the entire truck, front-to-back... It feels good to have her back on the road ! All systems nominal.