Stripped threads on transfer filler hole (1 Viewer)

Aloha Jen

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The previous owner left us a nice little surprise that we discovered last night. When we got the 60, the PO said he just changed all the oil in the transfer, transmission, and diffs....so it was lower on our priority list of things to check. Mike had noticed some very minor weeping of oil around the bottom of the transfer for a while. So we decided to change all the gear oil last night. When unscrewing the transfer filler plug, it was barely screwed down. Turns out the filler hole threads were completely stripped and not sealing it properly....and barely holding the filler plug in place!
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Seems pretty serious, like defiantly something you would want to be on there tight! This is pretty uncharted territory for us, so we are open to any and all suggestions on how to fix this. I really appreciate any advice on how to proceed.
 
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If you have a large enough drill and tap, you can drill and tap to the next size up and get a new plug. That would be the ideal fix. Helicoil is another option, i don't have experience with such large ones though. Thread insert or Helicoil

Creative Fix 1: drill and tap your current plug with a smaller hole. Then JB weld the old plug in place. Gives you a smaller plug though.
Creative Fix 2: JB weld a nut with the same threads over the current hole and re-use the current plug.
Creative Fix 3: JB weld is drill-able and tap-able. So you could JB weld the broken threads and then tap the hole back to the original size.
 
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You could temporarily plug with one of those universal rubber expand-o plugs used for stripped out oil pan drain plugs, or use an expanding plumbing plug of the correct size. This would buy you time until you can properly re-tap it, or find a more permanent solution. You could also clean up all the boogered threads, and wrap the fill plug heavily with US-made/quality Teflon tape, and thread it in the hole. The tape will bridge the gap and seal it, and may hold the plug securely enough.
 
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Options in order of preference:

1. Disassemble case, have hole professionally welded, re-machine and tap. (Cheaper/easier to source a new case.)
2. Helicoil repair as suggested (will likely put aluminum shavings in the case - I wouldn't lose sleep over it though.)
3. Tap to a tapered pipe thread.
4. Sorry but JB Weld is simply not an option.

If it were mine I would go Helicoil but the kits especially in the larger sizes are pricey.

Looks like you're in luck. Looks like the plug is straight 18mm thread - which is 0.708 inches. The tap drill to be used for preparation in tapping a 1/2" tapered pipe plug is 0.703" (45/64".) Close enough - don't even need to drill. Just need to tap the hole for 1/2 NPT. Be warned though that tapping for pipe plugs is a bitch as you're removing a lot of metal. Then you just use a pipe plug with Teflon tape when you need to service it. If you're feeling crafty with the right fittings this also gives you an option to extend the vent breather up wherever you want.

If you decide to go this route please re-check all my measurements and math.
 
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If you look at the hole you will see that the threads are cut out inside by the shape of the case, not leaving a whole lot of room for a proper number of threads. I had mine welded to build up the area around the filler hole and retapped to provide a nice meaty thread depth.
Transfer case fill plug repair.JPG
 
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I think the fix I had done is the most solid fix you can do, but I also agree with dinosaur that a rubber expandable plug will probably also work just fine. I had the Transfer out for some other fixes, and it was easy and relatively inexpensive to get it sent out for a welding and machining repair at that time.
 
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Yeah your's is a nice fix I just can't see welding a threaded collar on there while laying under the trick - and getting it leak free.
 

Aloha Jen

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Thank you all so much for all the suggestions and advice!! This is certainly and education for me since I know nothing about the re-tapping of threads, so I appreciate the knowledge you guys have.

You could temporarily plug with one of those universal rubber expand-o plugs used for stripped out oil pan drain plugs, or use an expanding plumbing plug of the correct size. This would buy you time until you can properly re-tap it, or find a more permanent solution. You could also clean up all the boogered threads, and wrap the fill plug heavily with US-made/quality Teflon tape, and thread it in the hole. The tape will bridge the gap and seal it, and may hold the plug securely enough.

The is no oil pressure in this location and the sitting oil level is below the filler. An expandable rubber plug is an accepable fix for this location

143-2 Series T-Handle Expandable Rubber Plugs

Dyno

I really like the sound of this option you guys mention, as we would prefer to not have to disassemble and remove the transfer to get this fixed (especially since everything is finally running so good after being down for so long!). So would something like this work:
Shaw Plugs 52098 Turn-Tite Expandable Neoprene Rubber Plug with Brass Handle and Zinc Plated Steel Hardware, 3/4" x 11/16": Industrial Expansion Plugs: Amazon.com: Industrial & Scientific
It says its 3/4" x 11/16", which should fit the hole opening ok right? But how about he depth? Also, please pardon my ignorance on this subject, but when you turn that T handle it expands? If so, it doesn't say what it expands to. What would be the ideal range for an expandable rubber plug for a stripped 18mm hole?
 

CaptClose

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Just pound in a wine cork.

This made me chuckle haha

Seriously though, there's two paths you can go down for this fix.

1. The right way
2. The good enough way

I've followed your thread. I haven't seen you guys do anything the "good enough" way so far. I get the temptation to just patch it with a bandaid because you're finally able to drive it. So, go ahead and cork it using any of the above methods. Then, start sourcing a new cover in the part out section.

When you get one, make sure all your threads are clean and retapped while it's off the case. You don't need any more metal shavings floating around your t-case. Then get a new gasket and swap covers. If you haven't already rebuilt your t-case, here is a good opportunity to do so.

You can leave it corked as long as you want, but eventually you should do it the right way. It would be a shame if you started cutting corners on that beautiful Cruiser.
 

mattressking

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This made me chuckle haha

Seriously though, there's two paths you can go down for this fix.

1. The right way
2. The good enough way

I've followed your thread. I haven't seen you guys do anything the "good enough" way so far. I get the temptation to just patch it with a bandaid because you're finally able to drive it. So, go ahead and cork it using any of the above methods. Then, start sourcing a new cover in the part out section.

When you get one, make sure all your threads are clean and retapped while it's off the case. You don't need any more metal shavings floating around your t-case. Then get a new gasket and swap covers. If you haven't already rebuilt your t-case, here is a good opportunity to do so.

You can leave it corked as long as you want, but eventually you should do it the right way. It would be a shame if you started cutting corners on that beautiful Cruiser.

Imagine the flavor after uncorking in a couple years. Definitely full-bodied, hopefully not too dry. Should have a good nose.
 
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drill and spiral flute tap (which will draw the chips out as it taps) That should do it. If need be, use a vacuum while drilling, just go slow.
 

hj 60

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Never trust the previous owner :hillbilly: just drive it, even a small leak wont damage it.
The thread size is M18 X 1.5 and there is plenty left if you get a longer bolt, only splash oil there so no need to hulktorque it.
The original plug seems oke but it is missing the copper ring (probably to make it use the deeper left thread) even some rtv paste should fix it for now.

Since I am lazy I would not retap the case now and the missing thread shavings hopefully washed out when drained.
It is just a filler / level hole and maybe a solid mounted adapter can be used for years:
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I am using these plastic plugs but these don't have enough thread for your case:


These are long enough and I have them for if the inner seal breaks:
file.php
 
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chit! i have the same exact problem. I went to check the oil in the t-case and the plug was barely sitting there. The po or his mechanic buggered it up badly. I have since (2 years ago) found a longer plug and made use of the remaining 2 or 3 threads to secure the plug. I also need to come up with a proper fix. I like the 1/2 npt tap best because it doesn't necessarily require taking the case off and it's probably the best fix.
 

MANUCHAO

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If you haven't rebuilt the TC along with the rest of the rig.. this would be a good time/ reason to do so....
I have a half housing (smaller idler shaft) of a TC with perfect treads that you can have...

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With that said..i ran the TC with a messed up fill plug for years... without any issues...
 

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