I hosed my NP231 transfer case fill plug

rocknxj · Dec 16, 2007

After a bit of research on this forum, I went to Autozone and purchased a 10mm allen socket to remove my transfer case drain and fill plugs. I positioned my drain tub beneath my transfer case and skid plate, and began removing the drain plug.

The drain plug came right out, but when I tried to remove the fill plug, it would not budge. That was an entirely new experience that I was not expecting. As many people have said on this forum, the plug felt as if it were welded in place. I tried again with my breaker bar, but all I did was round out the 10mm hexagonal hole with the allen wrench.

I felt my world sinking around me. I made another trip to Autozone and purchased a 7/16-9/16" easy out. I drilled a hole in the soft plug, popped in the easy out, and still could not remove the plug.

I now have a rounded out fill plug with a hole in it. Today I will try the next size up easy out and make the hole larger. If that does not work, I will tap a hole in the plug for a threaded bolt, replace the drained oil, and screw in a grade 8 bolt.

Perhaps in the future I can have a guy weld in the bolt and will remove it with that. In this process, I busted my garage door and now I cannot get to my tools easily. My Jeep is down until I fix it, and it will start to rain later today. Crap.

lazarus · Dec 16, 2007

next time your out at a p&p yard, or at the dealership, look for drain plugs from an older np231. I swapped mine with eth same allen to use the older style that is a 1 and 3/16 socket. no worries ever with stripping that thing. you may also try a lil propane heat on it, that will help relax the grip that case has on that plug.

falcon556 · Dec 16, 2007

rocknxj said:
After a bit of research on this forum, I went to Autozone and purchased a 10mm allen socket to remove my transfer case drain and fill plugs. I positioned my drain tub beneath my transfer case and skid plate, and began removing the drain plug.

The drain plug came right out, but when I tried to remove the fill plug, it would not budge. That was an entirely new experience that I was not expecting. As many people have said on this forum, the plug felt as if it were welded in place. I tried again with my breaker bar, but all I did was round out the 10mm hexagonal hole with the allen wrench.

I felt my world sinking around me. I made another trip to Autozone and purchased a 7/16-9/16" easy out. I drilled a hole in the soft plug, popped in the easy out, and still could not remove the plug.

I now have a rounded out fill plug with a hole in it. Today I will try the next size up easy out and make the hole larger. If that does not work, I will tap a hole in the plug for a threaded bolt, replace the drained oil, and screw in a grade 8 bolt.

Perhaps in the future I can have a guy weld in the bolt and will remove it with that. In this process, I busted my garage door and now I cannot get to my tools easily. My Jeep is down until I fix it, and it will start to rain later today. Crap.

Don't let it drag your spirit down, you know what scientists say "$hit happens"
If it was something that would compromise the structural integrity of the TC you would be right to be concerned. Just a filling plug.
Sears has been advertising some easy outs that looked good. It might be worth checking them out.
If you end up drilling and tapping the hole you will need to make sure that no filings fall inside the case. Coat the drill and the tap with some heavy grease to get any filings to stick to the grease.
If you use a bolt you will need a gasket also. Nothing fancy, there is no pressure there.

RichP · Dec 16, 2007

Also consider that the case is aluminum, the plugs are steel, they interact with each other over time and you end up with an almost welded plug in there

One of the reasons we say over and over again, remove the fill plug first. Also when I remove mine I use a 1/2" ratchet with a 3/8" adapter or a 1/2 breaker bar, you get more initial torque which tends to break it free.
Personally I would drop the TC and do this on a bench with the cover removed, only way to be SURE you get all the filings out. Whatever you do, do not break that easy out off. if you do it might be a good idea to just go by a trashed case with a good cover.

8Mud · Dec 16, 2007

Get a brass punch, set it on the filler cap and whack it with a hammer. Fairly hard, but not too hard. If that doesn't work, try just the hammer on the filler cap. The idea is to break the bond.
If it comes out hard at all, I don't even mess with it much and go straight to the hammer.
Wrap the plug threads in a layer or two of Teflon plumbers tape. People say there is a possibility that some tape will get into the transfer (motor, Diff, tranny or whatever). I've been doing this since 1977 (FSJ etc.) or so, with no problems yet. I use a pick and wire brush to remove any leftovers when I take the plug out.

falcon556 · Dec 16, 2007

RichP said:
Whatever you do, do not break that easy out off. if you do it might be a good idea to just go by a trashed case with a good cover.

If you do, you can drill it out using a carbide drill bit. It is slow but works.
Would an air hammer with a chisel be able to loosen it up?

rocknxj · Dec 16, 2007

Just a quick update for anyone interested. I ended up tapping 12x1.75 threads and installed a short bolt to seal the hole. I was careful not to get any filing in the case, or so I hope.

So far, no leaks. It's a cheese ball method, but I will have a buddy weld the bolt in place and will use that to remove the original fill plug. So far there are no leaks and I might just leave it for 30k miles. It's a Jeep, right?

Thanks to all for the advice.

I hosed my NP231 transfer case fill plug

rocknxj

NAXJA Forum User

lazarus

NAXJA Forum User

falcon556

NAXJA Forum User

RichP

NAXJA Forum User

8Mud

NAXJA Forum User

falcon556

NAXJA Forum User

rocknxj

NAXJA Forum User

Similar threads