2003 Avalanche NVG 246 Transfer Case issue?

[BigPapa]

This isn’t diesel related but I thought maybe one of you fellows could help me out. I have a 2003 Avalanche, 325K miles, well maintained, with the NVG 246 Transfer Case. My daughter drove it nonstop 300 miles to see a friend.

She had no problems until she got off the interstate and stopped at the light at the end of the ramp. When the light changed the truck wouldn’t move. She tried all the gears and it grabbed for a second in reverse. She tried 4-LO and 4-HI and it still wouldn’t pull. I forgot about the Auto 4X4 setting. A buddy told me to try that and it pulled itself off the road and into a parking lot.

It works for a little while but then stops pulling. It pulled itself up on a tilt trailer, but when I unloaded it I had to move it over a little on the trailer backing up then pulling up 3-4 times and then it wouldn’t back itself up enough for the trailer to tilt. I think it gets hot and stops. I got it on a lift today and drained and replaced the fluid with the proper GM fluid. I had hoped that maybe the fluid level was low, but it was full. The fluid was the right color of blue/green, so I’d say it had the correct fluid in it. It wasn’t overly dark, didn’t smell any different than the new stuff, and I didn’t see any trash in it.

Any ideas or do I just need to pull it apart?

 

[NIsaacs]

This might help.

https://r.search.yahoo.com/_ylt=Awr...7_10.pdf/RK=2/RS=zaVeyL9QmXBDmpCTOTrwsfXnAsQ-

 

[BigPapa]

I'll check it out.

Thanks.

 

[Ozymandias]

https://www.transmissiondigest.com/a-guide-to-the-nv-246-transfer-case/

Quite sophisticated unit you have.
Check for codes first.

My guess is it shifts/slips to Neutral as the rear shaft is a mechanical connection to the inputshaft, same as in our Ram TCs. Only the front shaft is activated from the clutch pack.

 

[NIsaacs]

What is steering you to suspect the t-case? What about the transmission?

 

[BigPapa]

What is steering you to suspect the t-case? What about the transmission?

It only moves in 4X4 Auto.

 

[DonFitzwater]

My transmission guy says to put a new transmission and transfer case in it (and he said to buy some lottery tickets if you are still running on the originals!)

 

[Tuesdak]

While you are there looking for trouble check for a oil seal leak on the driver side of the front diff. Then check the oil for being a "bad" silver color. Our 2002 Yukon ate the front diff a couple times: at least the second time was under the rebuild shop's warranty. (and they R&R'd it under warranty for free as I pulled it myself the first time. I'd have paid them regardless as some jobs you just don't do twice.) The lock for an adjustment nut came loose and the "new" gears and bearings grind up... The seals are a real PIA and redesigned a few times.

 

[BigPapa]

Well, finally got around to looking further into this. The truck’s been sitting for about a month. I started it up and pulled it into the shop. It pulled so well I decided to check all the TC gears. It acted the same in all of them this time and eventually lost reverse in all and then forward. I had taken a lot for granted instead of actually checking myself.

First, I had asked my daughter when it failed on her to check the transmission fluid and see if it was at the correct level, if it was red or dark, and if it smelled burnt. She’d told me all was good. I’m not blaming her, I should have checked it myself when I got there. She was distraught and in the dark.

Second, I guess it was just coincidental that it only pulled in Auto 4x4. The logic at the time that it only pulled in that TC setting pointed to the TC to me. If it was the trans, I figured it would not matter what the TC was in.

So, TODAY checked the transmission fluid. It black as my diesel oil and while it doesn’t exactly smell burnt, it definitely doesn’t smell right. So, now, we’re trying to decide on a reman, rebuilding it, or a used one.

I’m now in the position where I have to do something now, since my daughter ran her S10 off the road and caught a guy wire on a light pole. It’s going to be a longer repair than repairing the Avalanche and she has to have something to drive to work. And as usual, funds are tight from Christmas and missed work from COVID, and now I have two trucks to repair...

 

[Tuesdak]

Everyone is ok? That is all that matters.

Maybe use the rental coverage from your insurance and rent something short term.

Then @DonFitzwater mentioned, with 3x the design life miles on the powertrain, trans and transfercase both need to be refreshed. What's it worth? What shape is it in? And if the engine goes bang 60 miles after the trans work is it worth it?

Maybe look for something else?

 

[BigPapa]

Yes, she’s ok, and that WAS the most important thing.

The Avalanche is in good shape and I have next to nothing in it. I bought a used low mileage transfer case and, depending on the cost of the transmission, I’ll keep it and put it in, too. The motor is in good shape (knock on wood), doesn’t use much oil, no smoke, and it runs good. I do have a rear main leaking and I want to replace the seal on the oil pickup tube that’s known to fail.