Why is my transfer case fill plug leaking? Picture

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I have a 1997 GMC Sierra 1500 and keep my transfer case filled up to the bottom of the fill hole to the point it will leak out when you unscrew the fill plug. I have done it this way since it was new. I just flushed the fluid and filled it back up with fresh ATF and now the fluid is seeping out the fill plug. It leaks just enough that a new drop will form in a few days. The plug is tight and I dont know how it is leaking/seeping??? It has never done this before. Any ideas? Would plumbers tape stop it from leaking out? Here is a picture of how much seeps out in a day and eventually it will start running down and dripping.
tO2SOJt.jpg
 
You could swap the fill and drain plugs to see if its the plug or hole. I believe those are tapered threads so the thread clearance reduces as it gets tighter.
 
Wrap some yellow Teflon tape around it. The yellow tape is a bit thicker than the white, its used for gas pipes and works great.
 
Ignore it. Doesn't appear to be enough to worry about. Probably was over torqued. Usually 2-3 threads should be showing when properly fitted and torqued.
 
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May have have cross threaded or there was debris that got in the threads. Unfortunately you have a leak there get a thread sealant with PTFE.
 
Lots of good suggestions here. If it is not dripping a few drops overnight I would flush with brake cleaner, dry thoughtlessly then apply a ring of RTV or make-a-gasket / Make-a-seal (goop) around the outside of the threads. Don't get it in the square hole, just a ring around the threads to seal the weep path.

Next time you service the fluid, put some thread sealer on the threads before reinstalling the screw.


Also check to see that the oil is not coming from somewhere above the screw port and running down the body and only collecting there. The threads may be sealing fine but it is the lowest point on the part so any leaks above it will collect there.
 
Originally Posted By: demarpaint
Wrap some yellow Teflon tape around it. The yellow tape is a bit thicker than the white, its used for gas pipes and works great.


This ^^^^^^^^^^^^^^^^^
 
Originally Posted By: demarpaint
Wrap some yellow Teflon tape around it. The yellow tape is a bit thicker than the white, its used for gas pipes and works great.


^^^^ This. Its hard to goop oily threads, tighten firmly but don't over tighten tapered threads you can split the case, the tapers acts as a wedge.
 
teflon tape it..

Goop is too messy

just take out the plug inspect threads clean it (brake clean or whatever)

let dry tape it the correct direction for the threads and it will be fine.
 
Originally Posted By: dlundblad
Transmission output shaft seal leak and causing it to overfill?


I did just replace the output shaft seal as it was leaking. Maybe it is over full? Is that bad for the transfer case?
 
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