diff fill plug stuck solution (1 Viewer)

[CaptKevman]

Hey guys, hopefully this might help someone else. I rebuilt my front axle seals this past weekend. I won't get into the process of a knuckle rebuild, plenty of threads out there on that.

I tried to get the filler plug out first, didn't have any luck and figured I'd just come back to it.

After a major struggle including trying to weld nuts onto the fill plug, heat, chisels, hammers, impact guns and breaker bars, liquid wrench and did I mention the failure of welding a nut onto the fill plug...nothing works and it was time to get creative.

I went to my local hardware store and picked up a conical rubber plug that would fit into the drain plug snugly. I ended up drilling a hole in the plug and put a 3/8 inch clear hose through it and running the hose up through the engine and filling the diff via the drain plug. It took hours to get all the oil in there, but I got enough in that when I pulled out the plug and swapped the drain plug in I lost very little in the process.

This sucked. Do whatever you can to get that fill plug out first. And if all else fails, you can fill from the drain plug.

 

[dallen341]

or fill from the breather vent hole. It's small and would take forever but is doable.

 

[ScratchedFJ]

Thank you for posting this! I've been battling my rear fill plug since I bought my 80 series a few weeks ago. My now looks like the image attached. I was going to see if anyone makes a sufficiently sized screw extractor. I've tried a breaker bar, soaking in PB blaster for 48 hours (re-soaking every few hrs), an impact gun. Next up is map gas.

 

[NMC_EXP]

I could not keep a socket or wrench on mine and was rounding it off.

Finally broke it loose by placing a cold chisel on the outer edge at one of the hex points and tapping the chisel with a hammer. This after several soakings with Kroil.

If its stuck too bad this might just remove more of the plug head.

 

[nickolai]

Apologies if you have done this already, but I made a drain/fill plug SST. Just cut the chamfered section off a socket, that helps the plug get more engagement on the socket. Might not help here but might help someone else.

 

[pnwcruiser]

I'd spray a lot of penetrating oil on that over and over and let it soak for a couple days. Then put a 6 point socket on it, use an air or electric impact. You rounded off the corners a bit but hopefully you can still get it off. I'd also replace that plug bolt after with a new one.

 

[Rifleman]

Do whatever you can to get that fill plug out first.

Just as an FYI, It's a common maintenance practice to always remove the fill plug first, before you drain any transmission, transfer case, or axle. That way, if you're unable to remove the fill plug, you're not stuck with a vehicle you can't drive.

 

[lazy]

Why can't you weld a nut to it?

 

[SpenserAK]

I’m stuck on the rear currently too. I’m pretty damn sure I cracked all three fill plugs loose a few weeks ago, but rear wants to round out today for whatever reason. Things “look” just fine.” Going to be patient and heat, soak, tap, repeat until it gives, but so annoying. Should be such an easy job. Last thing I need to baseline, though, so that’s nice.

 

[ZackR]

Soak with pb blaster days in advance, flatten impact socket so it has a solid connection, hit it with a half inch impact wrench (forward and reverse) until it comes free.

 

[AndrewInf]

Had my own run-in with this recently on my rear axle. The fill plug has been partially rounded off and mangled for years. I've never been in there, god only knows how long ago the PO did his thing. I tried nearly everything mentioned on the forums short of welding a nut on there which would have required a bunch of reassembly to make the drive and finding a willing shop.

Tonight I finally got it off with a new set of vise grips + going HAM with a propane torch. I got it as hot as I could 3 times (500F according to the IR thermo) and let it cool off, then clamped the vise grips on there. This is a new-to-me style of grips with curved jaws, having the extra points of contact I think really helped over regular grips. I still couldn't get it moving by hand so I used my floor jack which finally broke it loose.

I'd given it a few propane torch cycles a few nights back and still couldn't get it moving with the cold chisel and a BFH. The sharp chisel tip was just cleaving off material from the bolt head (you can see in the pic below) so I think the vise grips had an advantage with the lack of impact and cutting tip.

Pics below.

Really annoying being held up for so long because of a damn bolt some idiot probably blasted on with a rattle gun 15 years ago.

The smell coming out of the diff after all that heating was horrible, still stuck in my sinuses 2 hours later.

The drain plug isn't as mangled, hoping I don't have near as much trouble there.

 

[zapatius]

I would recommend to use the 15/16" 6-point impact socket (instead of the "correct" 24mm). I soaked the plugs for a week with Deep Creep and used a 3/4" 2' ratcheting breaker bar. Came right off on first try. I would bet the use of 12 point 24mm sockets repeatedly on these is causing the rounded corners. Of course, replace with a quality Wit's End hex plug.

 

[Grandlooser]

Air chisel. 5 second affair. Have not met a nut or plug yet that wont come off, and I live around salt.

 

[ScratchedFJ]

I ended up soaking mine in PB Blaster for 48 hours (re-applying every few hours) and then torched it for awhile. Then I used my massive pliers to get a good hold on it. It looks like you removed the sway bar already but I also removed the spare wheel and other items nearby to allow for better clearance.