Transfer case issues

[Silverado2910]

I bought a 2004 Silverado 2500 HD and within a month I notice a slight grinding in the floor while driving.  A month later I throw it in reverse and she just sits and grinds.  Doesnt do this every time you drive it.  No codes are being thrown and the issue is intermittent.  I pulled with it two weeks ago and had issues once I dropped the trailer and drove home.  Wouldnt go in reverse, TC did a high pitched grind while driving down the interstate.  I bought the truck to pull with and I don't want to pull with it until this is fixed so she sits.   Is it possible to rebuild the TC?  Or should I just replace it?  Price difference is quite a bit so I'm hoping we can just rebuild and be done with it.  Its not leaking and for now it still shifts into 4l and 4h.  Its a 4 speed automatic, 6.0, 4l80e, floor shift, option MT1.  A refurbed TC is anywhere from 750 - over 1k.  

[davester]

First, is it full of fluid?

Second, is there any sign of fluid coming out of the rear of the transfer case.  Google "gm pump rub", and look through the results to find where the hole appears and then see if fluid is coming out there (it's higher than the "full" fluid level, so it doesn't come out and make a puddle when parked, it normally just comes out while the truck is in motion)?

 

Anyway, you can rebuild the transfer case, your truck should have the NP261HD model transfer case (vs NP261 and NP261XHD).  Bearings, bushing and seals aren't took expensive, but you need pullers and drivers to get them out & in (and some of the seals can be tricky to get in as they are 2-piece seals that you have to drive the inside and outside at the same time).  I also generally replace the graphite synchronizer disc (wrong name, it's a cone shaped friction disc used to make shifting in/out of 4wd smoother).  But other internal parts start getting more expensive, shift forks aren't too bad, but the chain, various gears, start getting expensive.  And you don't know what you need to get until you get it out of the truck, then you can start ordering parts.

 

From the sounds of it, your tc probably needs more expensive bits to get working right again.  I would suggest pulling the same tc from a junkyard truck, rebuild that with bearings, seals (there are bearing/seal kits available), output shaft bushing(don't know why these aren't in the kits), perhaps that disc, and a pressed-metal pump rub plate, anaerobic sealant (I used Permatex Anaerobic Flange Sealant, works well), and rebuild  that used tc, then swap tc's to minimize truck downtime.

 

Now, not going into reverse is a separate thing, as it sounds like you are primarily driving around in 2hi, and if you can drive forward, the transfer case is at least minimally working properly, and reverse will work just as well.  This sounds like the reverse band in the transmission is worn (happens with time & use).  Again, google something like "4l80e reverse doesn't work", for more info.  You can temporarily get reverse working (until it wears more) by installing a longer reverse pin (this can last quite some time), but the real fix is to replace the reverse band, and at that point, you might as well just rebuild the transmission.

[Silverado2910]

the reverse issue is very intermittent. In the last month I've drove it maybe 5 times, the only time the reverse didn't work was right after I pulled with it.  I could park the trailer but after I started heading home I stopped and went to back up and the gears just ground.  But I drove it this week without any issues whatsoever.  If it were a belt it would do it all the time, right?

 

We have not checked the fluid levels, we are doing that this weekend or next.  Probably should have done that when I first bought it, honestly,  

I cant seem to find a transfer case we can pull and rebuild.  So far the only thing we've found is a TC already pulled for 950-1100.  C grade is still at least 750.