Transfer Case Problems

Gozer · January 16, 2009

Truck is 2007 GMC Sierra NBS crew cab with max trailering package (6.0L, 4.10's, etc) and Autotrac transfer case.

I was having issues with slow engagement of Auto and 4Hi (20-30 sec). Dealership and GMC Customer service told me this is "normal". Then one snowy day, the 4Hi wouldn't engage at all (light flashed but went back to 2Hi). Thankfully the locker got me up the hill I was travelling at low speed. At top of hill, I hit the 4Hi again, and it went in after ~30 sec. Then there was a "clunk" from underneath when starting to drive. Ever since then I heard a grinding noise from underneath when in 2Hi. No noise in Auto or 4Hi, both of which still took 20~30 seconds to engage. This all happened between Christmas and New Years, and dealership didn't want to tear the transfer case apart since no parts could be ordered then (GM shutdown?). They told me it was OK to drive, but I only drove it sparingly

Anyway, finally got torn apart this past Monday. On Tuesday they tell me they can't find anything wrong. On Wednesday they tell me they did find a cracked plastic "shoe" which act as guides on shift fork. Also, the output shaft bearing had excessive roughness which they think led to noise. They ordered parts which are "factory", so it may take 1~2 weeks to come in. At least I have a rental (though a Cobalt with crank windows!)

Needless to say this whole thing is concerning. Anybody else had any issues like this with Autotrac transfer case? I have to wonder if it's anything related to the 6.0L power/torque and towing that I do with ~6500# travel trailer (well within the 10,500# rating for this truck).

chrisbmo2000 · January 16, 2009

Truck is 2007 GMC Sierra NBS crew cab with max trailering package (6.0L, 4.10's, etc) and Autotrac transfer case.

I was having issues with slow engagement of Auto and 4Hi (20-30 sec). Dealership and GMC Customer service told me this is "normal". Then one snowy day, the 4Hi wouldn't engage at all (light flashed but went back to 2Hi). Thankfully the locker got me up the hill I was travelling at low speed. At top of hill, I hit the 4Hi again, and it went in after ~30 sec. Then there was a "clunk" from underneath when starting to drive. Ever since then I heard a grinding noise from underneath when in 2Hi. No noise in Auto or 4Hi, both of which still took 20~30 seconds to engage. This all happened between Christmas and New Years, and dealership didn't want to tear the transfer case apart since no parts could be ordered then (GM shutdown?). They told me it was OK to drive, but I only drove it sparingly

Anyway, finally got torn apart this past Monday. On Tuesday they tell me they can't find anything wrong. On Wednesday they tell me they did find a cracked plastic "shoe" which act as guides on shift fork. Also, the output shaft bearing had excessive roughness which they think led to noise. They ordered parts which are "factory", so it may take 1~2 weeks to come in. At least I have a rental (though a Cobalt with crank windows!)

Needless to say this whole thing is concerning. Anybody else had any issues like this with Autotrac transfer case? I have to wonder if it's anything related to the 6.0L power/torque and towing that I do with ~6500# travel trailer (well within the 10,500# rating for this truck).

Slow engagement in an electronic t-case is not normal....did they say if they fornud anything in the fluid when the "cracked" the case? sounds like a solinoid problem. Ive not been "into" a newer style t-case yet but it sounds like the dealer only "found" part of the problem.....just doesnt set right with me, as far as the power/torque from the 6.0 I think you would see that more in the tranny and not the t-case and the trailer like you said is well within towing limits..................is this another case like dodge when the cummins came out and they were breaking bellhousings................maybe but I doubt it, sounds like premature worn parts to me caused by a solinoid "failure"

Good Luck

Chris