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I have an 04 Envoy SLT 4 by 4. I have to replace the axle bearing and seal because of a leak. My fill plug on the axle is froze. So I need to replace my differential cover. With one that has a fill plug. But I don't know what kind of axle I have. Therefore I cannot find a cover that fits with a fill hole. Does anyone know? Of one out there that will fit. That has a fill hole.?
 

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2004 Trailblazer LS 4x4, 4.2L:, 2016 ATS-V, 2014 CTS-V Wagon, 2018 Audi A7
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IIRC, the cover doesn't have a fill plug, the cast housing does.
 

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The fill plug in the cast housing is froze. I don't want to ruin anything trying to get it out. I figured it would be easier to replace. The differential cover with one that has a fill plug. Man taking a chance of ruining the whole axle housing
 

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2004 Trailblazer LS 4x4, 4.2L:, 2016 ATS-V, 2014 CTS-V Wagon, 2018 Audi A7
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Have you cleaned out the fill plug hole? Used a good 3/8'' square male socket on a breaker bar? Mine came out easily last month. Give it a good try before 'Plan B'.
Do they even make a diff cover with a fill plug? Have you looked on YouTube for drain n fill videos?
 

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My fill plug on the axle is froze.
This is not hard to deal with. Cheap Chinese tools can make the problem worse, destroy the tools, or both.

1. Dig out the dirt, grease, filth, rust, etc. in the wrenching surface of the original plug. You'll find one of several different styles of wrenching surface. It will probably be female (internal, or recessed) but it could be male (sticking out of the plug.) If internal, it could be square, it could be hex (like for an Allen wrench) or it could be Torx. Pretty sure the one on my axle is internal square, set up for a 3/8 square.

2. If the internal square is the same size as a ratchet extension, (1/4, 3/8, 1/2) DO NOT USE AN EXTENSION directly in the female square of the plug. The extension will be weak where the tip is drilled for the spring-ball socket retainer. You put an extension into the recess of the plug, and the extension twists off right at the spring-ball. I've seen this over and over with new-hires; most of them wrecked their extension within a day or two of being told NOT to use them on pipe plugs like the one on your differential. There are "special tool" pipe-plug removal sockets that are hardened steel and DO NOT HAVE A SPRING BALL in the tip. If it's an Allen or Torx recess, get the proper-sized Allen or Torx bit that fits snugly.

3. Grab your long-handled ratchet, get angry, and spin the bitch out of there. You MUST support the ratchet head, so you aren't putting side-pressure on the plug wrenching surface. A universal-joint between the ratchet and the socket makes this easier.

4. If #3 doesn't work, stop before you wreck the wrenching surface of the plug. Use an oxy-propane or oxy-acetylene torch. Propane, and MAP-Pro without extra oxygen will not be hot enough. Heat the PLUG orange, and let it cool. Don't deliberately heat the housing, concentrate the flame on the PLUG. When it's cool again, spin the plug out.
 

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Number two is important. Theses are good instructions.
 

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Apply heat using a propane torch around the fill plug (not on plug), then use a good quality 3/8" square extension.
 

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2004 GMC Envoy SLT 4.2
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I'd use a breaker bar . Then , if needed , an extension on the breaker bar handle . A right size piece of pipe comes in real handy , at times . ;)

Archimedes — 'Give me a place to stand, and a lever long enough, and I will move the world. '
 

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If I could go back in time, the one person I would love to meet is Archimedes. I've said that all my life.
 

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Have you cleaned out the fill plug hole? Used a good 3/8'' square male socket on a breaker bar? Mine came out easily last month. Give it a good try before 'Plan B'.
Do they even make a diff cover with a fill plug? Have you looked on YouTube for drain n fill videos?
I agree although I had to put a cheater bar on my breaker. I would even try letting some PB Blaster sit and hopefully soak prior. Unfortunately the reaction of the 2 different metals can be almost like a well
 

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I have an 04 Envoy SLT 4 by 4. I have to replace the axle bearing and seal because of a leak. My fill plug on the axle is froze. So I need to replace my differential cover. With one that has a fill plug. But I don't know what kind of axle I have. Therefore I cannot find a cover that fits with a fill hole. Does anyone know? Of one out there that will fit. That has a fill hole.?
Dont think they make a cover with a full plug, a drain plug maybe. There's a difference. Drain plug up top fill plug on bottom.
Spray that plug with some penetrating fluid and let it soak overnight.
 

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try letting some PB Blaster sit and hopefully soak prior.
Spray that plug with some penetrating fluid and let it soak overnight.
The drain plug is pipe thread. Pipe thread seals liquid- or gas-tight via thread deformation. HOW is a liquid going to get between the threads that are intended to SEAL LIQUID IN?

Total waste of time, money, effort, and enthusiasm. But at least it'll leave a nice oil-spot on the driveway where it uselessly drips off.
Drain plug up top fill plug on bottom.
Fill plug on top, drain plug on the bottom. Otherwise your vehicle is rolled-over, on it's roof.
 

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Actually, pipe threads alone do not seal liquids. Hence the reason all pipe fitters use some type of thread sealant when installing threaded mechanical piping systems. Sure, torque anything down extremely tight and odds are you won't have leaks, but then you over stress those threads. Still, the possibility of leaks is there.
 

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I agree although I had to put a cheater bar on my breaker. I would even try letting some PB Blaster sit and hopefully soak prior. Unfortunately the reaction of the 2 different metals can be almost like a well
This. I have never had a recessed drain/fill plug fail to come out with sufficient torque applied...and if you could see some of the prehistoric junk I've used on the farm, you would realize that I'm not making an idle statement.

PB and soak, or if that fails heat the area AROUND the plug. Heating the plug itself and letting it cool may work, heating the area around it WILL work; heat will expand the female threads, reducing the tension against the male thread of the plug. Be careful and don't start a fire or damage your vehicle being under there with a torch. A rosebud tip will work best if you have an oxy-acetylene rig.
 

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I had the same problem on my '04 Trailblazer. PB Blaster soak over a couple of days and breaker bar did not work. I finally took it to my local Goodyear and paid them $25 to take it out for me.
 
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