Possible transfer case issues?

TCasey · March 12, 2015

Hello all,

I'm new to the forums and can't believe the amount of info that is available to research problems for gm trucks. I have an 04' Z71 Tahoe w/195k miles (NP8 246 transfer case.) I think I have some transfer case issues due to a slight growling noise coming from the center of my vehicle. It occurs when accelerating but slowly goes away to a faint growl as I let off the accelerator. The noise is consistent whether the truck is in 2wd or 4wd. It can't be the tires due to the growl's response to the application of the accelerator. I have stock suspension. I just replaced both front hub assemblies about 4 months ago and it was obvious they were going bad. I replaced both front and rear brakes (pads and rotors) about 8 months ago. I have also replaced the fluid in both the front and rear differentials about 6 months ago as well. Two months ago I did replace the transfer case fluid with Auto TrakII fluid. The fluid did appear to be dark with a slight burned smell. However, the transfer case shifts fine from 2wd to 4wd vice versa with no clunks or noises. The 4wd still works great here in the Colorado snow and mountain trails. I did get under the vehicle and noticed there was play in the INPUT drive shaft to the transfer case, right where it attaches to the transfer case. Could it be the bearing going bad? The driveshaft connected to the output has no play whatsoever. Any advice? I'm thinking about replacing the case with a remanufactured one because it looks like a PITA to get to the input bearing.

Thanks everybody!!!

gmtech4 · March 13, 2015

Hello all,

I'm new to the forums and can't believe the amount of info that is available to research problems for gm trucks. I have an 04' Z71 Tahoe w/195k miles (NP8 246 transfer case.) I think I have some transfer case issues due to a slight growling noise coming from the center of my vehicle. It occurs when accelerating but slowly goes away to a faint growl as I let off the accelerator. The noise is consistent whether the truck is in 2wd or 4wd. It can't be the tires due to the growl's response to the application of the accelerator. I have stock suspension. I just replaced both front hub assemblies about 4 months ago and it was obvious they were going bad. I replaced both front and rear brakes (pads and rotors) about 8 months ago. I have also replaced the fluid in both the front and rear differentials about 6 months ago as well. Two months ago I did replace the transfer case fluid with Auto TrakII fluid. The fluid did appear to be dark with a slight burned smell. However, the transfer case shifts fine from 2wd to 4wd vice versa with no clunks or noises. The 4wd still works great here in the Colorado snow and mountain trails. I did get under the vehicle and noticed there was play in the INPUT drive shaft to the transfer case, right where it attaches to the transfer case. Could it be the bearing going bad? The driveshaft connected to the output has no play whatsoever. Any advice? I'm thinking about replacing the case with a remanufactured one because it looks like a PITA to get to the input bearing.

Thanks everybody!!!

If you check a front output of any tcase you'll find the same movement so stop jumping to replace it or the whole case ,,,,,

These things arnt diagnosed by guessing in the real garage world .... Say a dealer ,,

A tcase that is suspect is removed and comes apart ,a parts list is made out and an estimate is presented to you ....

Having said that ,,if the cost to repair is higher than an aftermarket rebuilt assembly costs ., then that estimate will be presented to you for authorization,,,

This is for diffs , engines, transmissions and t cases at the dealer level as they have techs that do this every single day ... I know this for a fact cuzz I've done this a few bazillion times lol

TCasey · March 13, 2015

^{Govtech, thanks for the input! Yea, I'm just torn because I know how much a dealer can cost vs. me attempting this myself. I know if I go to a dealer I could get the problem solved and fixed in a day or two, but at what cost, ~$1000-2000 or more..? I figure my cost would be the cost of a remanufactured tcase, 2 qts of AutoTrakII, beer (say $750-850 (expensive beer!! haha!), and a Saturday in the garage (my getaway from the weekly grind) Plus my Tahoe is an 04' that is easy to tinker on (especially just removing/replacing the tcase) and if I screw up it's not that hard or costly to fix.}

^{From your professional opinion and experience (or anybodys) is dark AutoTrakII fluid with a burned smell a good indicator of case on the fritz? The last time the fluid was changed was at 136,256 (now 195,300). Obviously I know you have limited information due to you not being able to inspect the case, but from your experience what do you or anybody think? Thanks!!!!}

Mckenzie · March 13, 2015

U joints?

TCasey · March 13, 2015

GrapeSoda- Nice Silverado w/230k miles! Gotta love these Chevys man. My ujoints were replaced at about 185k w/Moogs on both driveshafts.

Mckenzie · March 13, 2015

GrapeSoda- Nice Silverado w/230k miles! Gotta love these Chevys man. My ujoints were replaced at about 185k w/Moogs on both driveshafts.

Thank you sir! She's been good to me! My truck was doing almost the exact same thing as your Tahoe with the exact same circumstances. Noise around T-case, moog u joints less than a year old. Had a clicking popping noise around t case and i thought aint no way its those relatively brand new u joints but sure enough it was! Just some food for thought

TCasey · March 14, 2015

GrapeSoda- I'll have to get under the truck sometime this weekend and check those ujoints out again. From my last inspection it seemed as if the input drive shaft to the tcase had noticeable movement. I'll have to keep you updated

rudyb · March 22, 2015

Definitely don't rule out the u joints. I started getting a horrible squeak noise while accelorating and would go away when I take my foot off the gas. I couldn't get any play or movement out of the rear u joint on the front drive shaft, but after a closer look I could see some shiney metal in places. I assumed this was the result of wear. Once I finally pulled the shaft it was obvious that the U joint was toast. I replaced it and the squeak has gotten quieter but still exists. Not sure what my problem is, but I learned that u joints can still be bad even if they don't appear to have play. Good luck.

gmtech4 · March 24, 2015

^{Govtech, thanks for the input! Yea, I'm just torn because I know how much a dealer can cost vs. me attempting this myself. I know if I go to a dealer I could get the problem solved and fixed in a day or two, but at what cost, ~$1000-2000 or more..? I figure my cost would be the cost of a remanufactured tcase, 2 qts of AutoTrakII, beer (say $750-850 (expensive beer!! haha!), and a Saturday in the garage (my getaway from the weekly grind) Plus my Tahoe is an 04' that is easy to tinker on (especially just removing/replacing the tcase) and if I screw up it's not that hard or costly to fix.}

^{From your professional opinion and experience (or anybodys) is dark AutoTrakII fluid with a burned smell a}

((((((((good indicator of case on the fritz? )))))))))))

The last time the fluid was changed was at 136,256 (now 195,300). Obviously I know you have limited information due to you not being able to inspect the case, but from your experience what do you or anybody think? Thanks!!!!

Please refer to post #2 on estimate explanation .... Again

TCasey · March 25, 2015

Thanks for the input everybody! Still waiting to get under the truck, possibly this weekend. I hope it's the u-joints. If it is I owe you all some brewskis.

gmtech4 · March 26, 2015

Thanks for the input everybody! Still waiting to get under the truck, possibly this weekend. I hope it's the u-joints. If it is I owe you all some brewskis.[/quo

Post an audio/video to end this

TCasey · March 28, 2015

GT-Time stamp scheduled to be punched @ 0900hrs... Getting antsy? Us yanks are almost thawed out and would rather be playing than working on the weekends. You crazy canucks must still be snowed in suffering from some cabin fever. haha! j/k The noise is getting louder so I'll definitely get under the car this weekend so I can go play next weekend.

TCasey · March 30, 2015

Update and resolution: I owe you all! It was a failing (new) ujoint! Lesson learned. Never assume a new part is good to go just because it is new. Thanks again everybody!!

Mckenzie · April 6, 2015

Update and resolution: I owe you all! It was a failing (new) ujoint! Lesson learned. Never assume a new part is good to go just because it is new. Thanks again everybody!!

glad you got it fixed man!!! New parts fail a lot more than people would think ! I had a brand new alternator that was bad and I believe the new master cylinder I put on my 78 jimmy is bad as well !

Sent from my iPhone using Tapatalk