Transfer Case started making noise

[Kwikkordead]

Hello everyone.  New guy here with an older truck. 2002 Silverado 4x4, 4.8 V8, stick shift, manual transfer case.  Everything was fine until last week when I was out in the truck and started noticing a scratching noise coming out of the transfer case in low range only.  Also can duplicate the same noise if I put the transfer case in neutral, and put the transmission in gear.  It sounds to me like there is a failure in the low range planetary or something like that.  I put new Dex III in it but that only quieted it down some, so I know I have a rebuild coming up in my future.  Looking for any tips and pitfalls that you may have experienced if you have done the same thing.  Thank you all for your time.

[richard wysong]

Loose chain wears a hole into the oil pump is the most common

[Kwikkordead]

Well that makes sense.  This symptom showed up pretty suddenly and it sounds exactly like it ran dry for some reason.  It also explains why so many rebuild kits come with a new chain and oil pump.  I've rebuilt only one other TC in my life and that was the one on my Ford F550 about 15 years ago now and it was a little different inside than this one. But it was pretty easy to get the job done and I'm hoping this time around it should be just as good.

[Kwikkordead]

Upon further reflection of the symptoms demonstrated by the TC, I'm pretty sure that the planetary gear has failed.  Only makes the noise in low range or TC in neutral with the transmission in 5th gear, parking brake applied.  I guess I'll just have to pull the unit and disassemble it before making any other conlusions.  Thank you all for your time.

[richard wysong]

what do you use low range for? I have had 4wd trucks all my life and almost never use low range.

[dna9656]

Check out https://www.merchant-automotive.com/ for your parts.