Yes, I'm an idiot; turned the drain plug on my transfer case the wrong way and stripped all the threads out of the case and buggered the threads on the bolt somewhat as well.

I was hoping to find an easy fix, but this is proving to be somewhat elusive. I haven't calipered the bolt but the front diff fill plug is 20mm x 12mm and looks similar. As one would expect, though, I can't find any metric parts in the local market.

Any idea if a 3/4" self-tapping drain plug would work? I think 3/4" is smaller than 20mm but maybe with the threads etc. it's somewhat oversized.

How about heili-coil? Again, I can't find metric, but I'm wondering if a 3/4" tap and heili-coil might allow me to use my 20mm bolt or I should be able to pick-up a 3/4" drain plug.

Any other ideas? Right now the drain plug is being held in with plumbers tape and blue locktite <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

TIA

I don't know if its the best solution.... but check out THIS very recent thread from Isuzu Talk.

Sounds like an interesting temporary solution (I'll have to pick some of those up) unless someone has some long-term experience using those as a drain plug.

Any other fixes?

"Any idea if a 3/4" self-tapping drain plug would work? I think 3/4" is smaller than 20mm but maybe with the threads etc. it's somewhat oversized."

I asked a mechanic friend of mine, he said the only way to go is a self tapping over sized plug. Also be VERY careful it goes in straight. Heili coils do not work on old drain plugs. Good luck. <img src="/forums/images/graemlins/patriot.gif" alt="" />

this kinda sucks Jim. If you cant find a solution sometime soon I may be able to hook you up with a whole rear cover to the case. I think the plug is on the rear half of the case.

Troy

Yep, plugs are on the rear half of the case, but ... Tonka ain't bein' parted out ... now, if you had a spare t-case lying around .... say an auto t-case ... <img src="/forums/images/graemlins/pfft.gif" alt="" /> ... I'd still need a fix cause I'd be using that auto t-case for something different ... <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

Has anyone calipered their t-case drain bolt? I have to come clean and admit, my measurements above came from my front diff bolt (Hey they both have a 24mm hex nut on top, they could be the same ???) ... but, I'll be honest, I did that because I really didn't want to drain and place that plug again in case it wouldn't take, so ... maybe ... the t-case drain plug is smaller in diameter than 20mm and a 3/4" self tapper or 3/4" tap and bolt would work?

FWIW I found out today that a 3/4" "pipe-thread" is WAY larger than 3/4". What were those guys smoking when they came up with that??? <img src="/forums/images/graemlins/drunk.gif" alt="" /> [Hey Bob ... see that pipe over there that's about as large as your head ... what say we call that one 3/4" ....]

FWIW (2) I did also find that I can get "over-sized" drain plugs (oil not t-case but similar(?) ), so if I can get an accurate measurement, perhaps I can get one of these ... still have to tap the t-case though cause the threads are gone ....

FWIW (3) the thread pitch on our t-case drain plugs (OK oil drain plugs - but I'm assuming now that they're similar) are 1.50 if anybody cares....

Any other ideas??

Tonka is quite safe for now. I decided to just finish up the dual case project and then get a new rear drive shaft made.


I do have a spare rear case cover at my brothers place in castle dale though. I am sure we could work out some kind of a deal the gears are all out of it, meaning you would have to install yours into it. I am pretty sure it would fit yours. I believe it is the rear of an amigo t case, but I believe it is the same as the rodeo's.

Troy

The BEST fix is a new case.

The second best fix is to pull the rear case and have a machine shop fix it. Yes, Heli-Coil does make repair kits that big and metric, but...they don't actually stock them. But, for about $4 each, you can get the insert. But, you have to buy about a hundred of them.

I had a machinist mill out the threaded area and install a press fit steel insert that was threaded for a new plug. But, it also cost me about $150 bucks. I had my reasons and the work was so beautiful that it would make you cry.

Barring that, the rubber plug is your next best bet, followed by a stick wittled into a point and jammed in there.

I would stay away from the self tapping plug. The case is aluminum, and Al does not take self tapping things installed and removed again and again and again, very well.

Good Luck,
Michael

PS, this should all be followed up by laying off the anabolic steroids and having tattooed on the back of your hand, "Righty Tighty, Lefty Loosey". <img src="/forums/images/graemlins/smile.gif" alt="" />

Hmmmmmmmmmmmmmm ... a stick wittled into a point and jammed in there you say ... sounds promising .... <img src="/forums/images/graemlins/shiner.gif" alt="" />

I did drain the t-case (again) tonight and calipered the plug. It is 20mm (19.8mm to be exact) or .77" and obviously too big for a 3/4".

Troy, based on Michael's input ... how 'bout $149.95 for that spare t-case?

Regardless though, I think I'll still order a 13/16" or 21mm tap and plug and get one of those rubber plugs as an additional back up. I never know when dyslexia will strike again.

Thanks all for your insight.

Seriously, I would just go with the rubber expansion plug. If it fits correctly, it is impossible for it to fall out. Hell, it may be hard to just remove it. I have spent hours on my back prying them out of engine blocks because they get hard, form a ridge on the inside and do not shrink when they are unbolted. I don't think you will have this problem with the transfer case.

Worst case, glob some sealant on there and be happy with it. To drill and tap, you are going to have to split the case anyway and by the time you buy a bit and tap, you are going to be into it for some $$. Trust me, I spent a long time looking at this problem. Like, a year and a half, while my truck was apart. Now that I think about that, that $150 price was for both plugs. So, it was just down to a minor whimpering over the cost. And if you think about it, that is still only 2 hours of shop time.

If you can find another case, anywhere, do it. The other reason I went the machine shop route was to solve the galvanic corrosion problem. Other that Isuzu having a brain fart and putting a threaded plug into an Al case, they also put a steel plug into an Al case. Outside of the brute force failure mode(i.e, what you did), these puppies just weld themselves into the case, even in the constant oil bath.

As I said, the best is a new case, other than that, don't screw with tapping it. Just plug it and go on your merry way.

Michael