Sounds exactly like a spent driveshaft to me. Just replaced one in a buddy's ride and it sounded just like that especially while turning! Hope this helps!

 

thanks i will try it maybe this weekend! did it make that sound while in 2wd as well?

 

It was suggested that I share this info by someone wiser than I:

Regarding the front drive shaft - per GM service info in TSB 02-04-21-005A ( not applicable to this problem - but there is language in there that describes the proper operation of the tcase )

"Vehicles with a NVG 236 or 246 transfer case (RPO NP8) have a preload in the clutch pack of the transfer case that supplies torque to the front driveshaft at all times. The front and rear driveshafts should be rotating at approximately the same speed (the front driveshaft display on the Tech 2® may be slightly higher but never less than the rear)."

and

"For vehicles with the NP8 transfer case option (Autotrak with push-button selections for 2HI. Auto 4WD, 4HI, 4LO and Neutral) only, when a vehicle comes in for issues with the front axle, the transfer case should also be inspected for overheating by inspecting for burned fluid or a free rotating front driveshaft. In addition to correcting front axle concerns, necessary repairs should be made to the transfer case."

Also, by following and reading swartlkk's rsgear.com references, some other auto 4wd cases modulate the actual torque amount to the front axle from 5% to maybe 50% depending on sensed conditions.

From this collection of info, it would seem that the front driveshaft ( on this particular model tcase ) is NOT free to rotate in any mode, so be careful what conclusions are drawn by removing the driveshaft.

It may still be related since the amount of torque transmitted varies, but it is not just on or off.

 

Yes, the above information states that the clutch pack in the transfer case is preloaded. Due to the information I have found in numerous other places, I have been undecided about whether the clutch was preloaded. Many more references state that it is not than those that state that it is and that includes people that have the Auto4wd model, but that does not mean that there were not other problems.

Thank you for the information. Reading the rest of that TSB, it does appear that the clutch pack in the NP8 (NV236) transfer case is preloaded which would mean that it should turn even in 2WD. Up until reading that TSB, information has been very unclear, most of which has come from this and other forums. Due to the lack of properly detailed information on these transfer cases, it is aweful difficult to diagnose them, especially from hundreds if not thousands of miles away.

 

so what am i looking for to replace? and how much roughly is all this? arg stupid IFS