TROUBLE: Stripped fill hole inlet threads on Transfer Case (1 Viewer)

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I was changing my transfer case fluid. All was well until i put the fill plug back in and torqued it down to hard. I didn't have a torque wrench so i was free handing it with a ratchet. It spun loose after some pressure, i knew what had happened.

I was hoping that it was the plug that stripped and not the inlet threads of the transfer case. My hopes came up short. I'm pretty sure I stripped out the threads to the inlet of the T-case.

When i pulled the plug out, it had what looked to be a spring around the plug. It turns out they are metal shavings from the T-Case that i apparently dug in when torquing too hard on the ratchet? See pic

Thoughts? Advice?

I put the fill plug back in and have it softly contacted/tightened as much as it will go again before it slips loose again.

Should i put lock tight on the washer where it will meet the side of the inlet of the fill plug hole and tighten it as best as i can and hope the lock tight holds? ...........and then just never plan on changing the transfer case fluid again? Anything a mechanic can do?

I guess it's a small win that i stripped out the fill plug and not the drain plug? Maybe the leaking will be minimal?

stripped.jpg
 
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Kind of a rough and crude solution but it can work:
Find a slightly larger plug (1 or 2 mm if it exists) or an SAE size that is very slightly larger, and force it to tap new threads in the aluminum case. This is how I ended up with an SAE fill plug on my 80 :D
 
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In the meantime you might try a rubber expanding plug bolt rather than the loosely-fitting threads you've got now.
 
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Would the rubber be able to stand up to the temps of the hot transfer case gear oil?

Would tapping it with a larger bolt result in me not being able to pull the plug out ever again?
 

Mike6158

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It's too late for something like this:

https://www.marlincrawler.com/hardware-tools/tools/18mm-tap-drain-or-fill-plug

But "someone" should be able to tap the hole to the next size. The problem with tapping the hole is that cut metal shavings end up inside the transfer case. Not good. You would need to drain the fluid to make it easier to get the shavings out (vs being suspended in a viscous fluid).
 
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Would the rubber be able to stand up to the temps of the hot transfer case gear oil?

Would tapping it with a larger bolt result in me not being able to pull the plug out ever again?

I wouldn't use the rubber plug as a long term solution.
Taping a new hole--either with the proper tools or by the method I described--should make everything good again. BUT, you can screw up the tap and end up in the same place you're in now, albeit with an even bigger hole.
I'd also do a couple drains and fills to get out any cuttings, as suggested.
 
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I would bite the bullet and gladly drain the fresh mobil 1 out if it meant getting the metal shavings out that will come from tapping it.

My question is would the fill plug that they tap to the next size up be a functional plug for the long term or would it need to stay screwed in once it is tapped in? Would i be able to fill the transfer case back up with gear oil?
 
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I would bite the bullet and gladly drain the fresh mobil 1 out if it meant getting the metal shavings out that will come from tapping it.

My question is would the fill plug that they tap to the next size up be a functional plug for the long term or would it need to stay screwed in once it is tapped in? Would i be able to fill the transfer case back up with gear oil?

Mine worked fine. I figure as long as the plug is harder than the aluminum case (they generally are), then it will cut threads and work as a functional plug, meaning it will screw in and out. However, a proper thread tap with a tool designed for cutting is the best solution. Just wanted to offer a fix that worked for me. Your results may vary.
 

Mike6158

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I think it would be usable if it's done right.

Way back in the day I screwed the oil drain plug up on a Moroso oil pan (aftermarket and expensive) on the 402 in my /69 Camaro. The local auto supply had an over sized, self-tapping, drain plug. It was still in the car when I sold it a few years later. Idk if auto parts stores carry things like that anymore.
 
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Google revealed a plethora of "self tapping oil drain plugs," so you might very well be able to find an oversized self-tapping fill plug.
 
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anyone happen to know the size of the fill plug on a 99 Land Cruiser? Would need that info in order to determine the next size up.
 
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If you choose to tap without draining the case, you can slather the tap with grease. That will catch the majority of the shavings.
 

hankinid

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OUbobcat...this is in response to your personal message.

I did similar damage to my last Suburban...trans case drain was a tapered stainless pipe plug threading into an aluminum transfer case...stuck a ratchet on that biatch and kept tightening it. Noticed a drip the next morning from a crack in the case. :( :censor::flipoff2:

You've got a short term fix as well as a permanent fix...


In the meantime you might try a rubber expanding plug bolt rather than the loosely-fitting threads you've got now.

That's the short term fix, and I think it will give you plenty of breathing time...find a hardware (not HD or Lowes) store with a good selection of hardware...2 kinds you can use. First has a flip over tab to expand the rubber stopper and it's adjustable to fit various holes...second has a t-handle to expand the plug. I use them as fill plugs for tractor hydraulic tanks, oil baths, etc. Check plug tightness weekly and I'd suggest it for around town type driving.

The permanent fix, while you're driving around with a rubber stopper...

Find a repair shop or machine shop that can heli-coil the drain hole to fit a standard drain plug. That will involve tapping the hole oversize, adding a stainless thread insert, and that's it. You could diy it, assuming cost of the tool will be less than shop labor. Time involved should be 10-15 minutes. Greasing the tap as was posted before will keep 99% of the shavings out of the case...what's left will be aluminum particles which won't cause wear on the case internals.


I would bite the bullet and gladly drain the fresh mobil 1 out if it meant getting the metal shavings out that will come from tapping it.

My question is would the fill plug that they tap to the next size up be a functional plug for the long term or would it need to stay screwed in once it is tapped in? Would i be able to fill the transfer case back up with gear oil?
An oversized plug in a tapped hole or a helicoil repair would both be removable, just like oem.

I'd recommend the heli-coil v. an oversized plug, but either would be permanent.

Measure your existing plug...next oversize should be 2mm larger. Helicoil will be the same diameter as your factory plug when finished.

Your homework...USE YOUR EFFIN TORQUE WRENCH ON BOTH DRAIN AND FILL PLUGS...FSM SAYS 27 FT.-LB. :)

If you can't find an adjustable temporary stopper, pm me.

eta...I think, but I'm not positive, the plug is 18mm, but I don't have any washers in my stash to verify. You'll need a new one anyway, and I would buy a new plug.

hth

Steve
 
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Great information, guys. This community/forum is beyond valuable.


Just to clarify, the fill plug does have some bite left to it. It's on there now, and I can't bust it loose by hand (if i put a socket or wrench on it will strip/bust loose pretty easily though). I put a wad of paper towels over the fill plug to give my hand/fingers more torque and it still won't tighten any further or strip loose by hand. It's not just spinning freely.


I do want to avoid a catostrophic failure. Will the CEL throw a code if it loses to much gear oil from the transfer case? I will be actively monitoring it and checking around the fill plug for leaks. How much does a new transfer case run? Cost to rebuild a transfer case? Any guesstimates?


I'm thinking i'll leave it like it is and see if it will hold the fluid. I'll get some rubber expanding fill plugs to have handy just in case.

I'll look for a permanent fix before next March where I have a 4500 mile - 12 day road trip planned (Indy ---> Steamboat, yosemite, ouray, telluride, Moab, Grand Canyon, Flagstaff, Sedona, Scottsdale ----> Indy).
 
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The helicoil advise is the best. I'd try that before anything else and it should be a long term solution.
 

hankinid

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Just to clarify, the fill plug does have some bite left to it. It's on there now, and I can't bust it loose by hand (if i put a socket or wrench on it will strip/bust loose pretty easily though). I put a wad of paper towels over the fill plug to give my hand/fingers more torque and it still won't tighten any further or strip loose by hand. It's not just spinning freely.

I do want to avoid a catostrophic failure. Will the CEL throw a code if it loses to much gear oil from the transfer case? I will be actively monitoring it and checking around the fill plug for leaks. How much does a new transfer case run? Cost to rebuild a transfer case? Any guesstimates?

I'm thinking i'll leave it like it is and see if it will hold the fluid. I'll get some rubber expanding fill plugs to have handy just in case.
If it will take 27 ft-lb without turning, I'd say you're OK.

I would bet it won't throw a code if empty, until / unless some function of the trans case that would throw a code would not work.

I would guess a new trans case would run well north of $1000...you could call a dealer and ask. You don't need a rebuilt case...all you need is a thread repair for the fill plug, and a new plug and washer. Plus more fluid. I'm thinking $100-ish, assuming you can find a shop with the right tool. A dealer could give you pricing on new v. repair, I would think.

Steve
 
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I don't have a measurable torque wrench................which is why im in this mess to start with.

How much torque you think I'm putting out with my hands and cloth over the bolt/plug haha?

Is this heli-coil kit something i could perform from under the truck. Last thing i want to do is screw it up even more. Is it generally something that shops are familiar with? My first call to an independent shop i mentioned heli-coil and he thought i was speaking french.
 
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I don't have a measurable torque wrench................which is why im in this mess to start with.

How much torque you think I'm putting out with my hands and cloth over the bolt/plug haha?

Is this heli-coil kit something i could perform from under the truck. Last thing i want to do is screw it up even more. Is it generally something that shops are familiar with? My first call to an independent shop i mentioned heli-coil and he thought i was speaking french.
Keep trying to find a place that is experienced in industrial/auto/trucking repairs and not just remove and replace. Heli coil inserts certainly used to be very common and approved repair method, as a young military hydraulics/electrical fitter mechanic apprentice we were trained and tested on correct prep and instal of Heli coils to meet or exceed OE strength and durability and I'm sure those sorts of skills are out there, trouble is the 20 something year old concierge service writers at big dealers etc just don't know about this sort of stuff. Keep calling around places like truck repair specialist, Indy garages, hydraulic service mechanics and you'll get lucky. If you attempt it yourself you need the correct tap and insertion tool, heli coil and plug with matching thread.
 

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