Can't remove diff fill plug - Ideas?

[97 EB Mike]

Working on a 94 for a friend of mine. This truck has lived its entire life in the rust belt, and the rear diff plug simply isn't coming out with a 3/8 drive tool. I have a few ideas, and would like the opinion of someone with more experience.

Idea 1: drill out the fill plug and remove with an easy out/reverse drill bit/whatever works. The problem I see here is damaging the ring gear or getting a hole in the plug and still not being able to remove it.

Idea 2: Weld a small piece of steel in an open cavity on the back side of the cover, then drill and tap it to accept a plug/gasket combo similar to an oil pan plug. The problems I see here are: having to fill based only on the known capacity instead of filling until it drips out, the steel welded on the inside of the pan interfering with the gears/bearings in the diff, and burning holes in the cover when trying to weld a piece of steel in it.

Idea 3: Fill the diff through the vent tube based on known capacity. The problem I see here is potentially shoving a bunch of dirt/rust/other impurities into the diff oil, and having to fill based only on known capacity.

I know there are aftermarket covers available that have plugs in them, but I have not found one that is cost effective. If anyone has any better ideas, other potential problems with my ideas, or any thoughts in general, I'm all ears. Sorry for the long post, and I thank you for your time.

 

[99ex22]

Try heating it up a little bit

 

[lounge lizard]

then try tightening it a little first. some times just turning it in just a touch will break it loose for coming out

 

[97 EB Mike]

Thank you for the replies, but rust holding the plug in isn't the current problem. Rust has deteriorated the square recess beyond use. I've cleaned it with a screwdriver, a brass brush, and a wire wheel on a dremel. I'm down to bare steel in the recess, and it's only about 1/16 - 1/8" deep. I can't see how I could get it out with a 3/8" drive tool.

 

[unclemeat]

I have heard that you can put the fluid in a plastic bag and put it in the diff with the cover off. I dont know if i would do it to my axle.

 

[Ronin8002]

I have heard that you can put the fluid in a plastic bag and put it in the diff with the cover off. I dont know if i would do it to my axle.

:scratch:

 

[Ronin8002]

Thank you for the replies, but rust holding the plug in isn't the current problem. Rust has deteriorated the square recess beyond use. I've cleaned it with a screwdriver, a brass brush, and a wire wheel on a dremel. I'm down to bare steel in the recess, and it's only about 1/16 - 1/8" deep. I can't see how I could get it out with a 3/8" drive tool.

Maybe you can tack weld a piece of rebar to the plug and use the rebar as a wrench of sorts. then just replace the plug with a new one.

 

[97 EB Mike]

Maybe you can tack weld a piece of rebar to the plug and use the rebar as a wrench of sorts. then just replace the plug with a new one.

I like the idea, but I don't have a welder at home. I work in a steel fab shop, which is where I thought I'd have a piece welded into the cover to drill and tap.

The more I think about it, I believe my best solution with what I have at my disposal is going to be filling through the vent tube. I'll just pull the old rubber hose off and clean the area well. Will update in a couple days. Thank you all for your help.

 

[Facimeor]

Any muffler shop worth its salt should be able to weld the treaded end of a short bolt to the plug, then you would have the hex head of the bolt to put a good strong impact on and drive the plug out.

Or buy a 3/8 to 1/2 drive adapter and weld that to the plug. Something like JB weld may be enough to hold an adapter in there if there is any depth to the original plug hole at all.

 

[Maniak]

Many aftermarket diff covers have a fill hole. I know ruffstuff and the solid and rockcrusher ones do.

I'd be afraid that the old fill plug finally rots all the way out and you end up with a hole on the front of the diff letting dirt/water etc into it.


~Mark

 

[97 EB Mike]

Facimeor - The problem here is that the diff is empty. The closest shop is about 2 miles from my house, but even that is farther than I am willing to take an empty diff. I've never had any luck with JB weld in any capacity, probably because of my lack of proper preparation. But proper prep here is nearly impossible.

Maniak - I have found a couple covers with a fill hole, but they were in the $140 dollar range and up. That's more than the truck's owner wants to spend. I had the same concern about the stock fill plug at first too, but looking behind the ring gear, the plug looks like new (likely from spending it's whole life in gear oil) and there were no signs of leakage from the outside of the case. It feels like a pretty solid piece of steel below the surface, but I suppose one can never really be sure until it's too late.

Are there any real negatives to filling from the vent? I've never had to do it that way, but in theory it seems like it should work as long as it isn't overfilled. I've never paid any real attention to the vent hole, but it's just an opening straight into the axle tube isn't it? Is there some piece of info I'm missing?

Thank you all again for your time. This is becoming a little more of a learning experience than I had bargained for

 

[Maniak]

Yea, the stronger diff covers with fill holes are > $100.

You can find actual aluminum factory ford diff covers. You could braze in a fill hole/plug. Heck, you could drill a hole and use a rubber plug. The rubber plug is what the clear gearz clear diff cover uses.

As for putting it in through the vent hole. Yes, once the vent is off, its just a small hole. I can't remember where the "lip" is in the tube though. If its betwee the vent and the diff itself your gonna have a lot of diff fluid in that side of the tube. I guess you could tip the vehicle up some to get it to climb over the lip. If the lip is farther into the tube then thats not an issue.. Its just been too long since I looked down my axle tube.

~Mark

 

[97 EB Mike]

You can see the "lip" from the end of the axle tube? If that's the case, I'm really not far from pulling the axle again. That's the reason I drained the diff to begin with. Maybe I'll pull it back out and have a look. Shouldn't take more than a few minutes to do from this point, as long as I haven't broken the new lock bolt yet...

 

[Foxracin]

Fill it through the abs sensor hole on top of the diff. Take the little bolt out of the sensor and pull it out and you have a nice size hole to fill it. Then just put it back in.

 

[Maniak]

Thats a great solution.. and its right in the "diff"..

~Mark

 

[Facimeor]

Ahh yes I see the problem now. Yeah the sensor hole should work for a fill point. But once its full and driveable you should have options for the future to get the old plug out.

 

[97 EB Mike]

Fill it through the abs sensor hole on top of the diff. Take the little bolt out of the sensor and pull it out and you have a nice size hole to fill it. Then just put it back in.

And this is why I love this forum. After reading this post, I had that "WOW, why didn't I think of that" moment. I just pulled the sensor, and this method is going to work beautifully. Thank you so very much Foxracin! You have just saved me a HUGE headache. Just before I checked the forum, I was preparing to drill out the fill hole...

 

[Foxracin]

No problem. You will get the bill in the mail. lol

 

[97 EB Mike]

Just an update for anyone who may have been curious - The rear end is together. Filling through the ABS sensor hole worked beautifully. Thank you all again for your time and ideas!

 

[Fredness]

Necro!
How about the vent tube hole? I see it listed, but has anyone tried it?
I'm in the same position with a seized fill plug, fresh cover gasket install and no ABS (Early rear). Thx