Transfer Case noise

[shopclod]

Hello, I have a 1996 Yukon with 104k. I am looking for some assistance in diagnosing a transfer case noise. On normal acceleration there is a loud whirring noise. The trans does not appear to be slipping and shifts fine. It almost sounds like a partially engaged gear. The noise disappears when 4 wheel drive is engaged. ( dash push-button ). Cruising at a slow speed in 2 wd you won't hear it, however when I went over a slight bump in the road, it made the noise momentarily. Is it possible that the electric actuator at the transfer case has failed somewhat and the gear is not being held in the right position? I would appreciate any thoughts you may have!

[shopclod]

Well thanks to a friend of a friend who happens to be a GM mechanic at the local Chevy dealer the problem has been found. A broken snap-ring on the output shaft of the transfer case for the rear drive shaft was causing the problem. Its a fairly easy repair. Remove the drive shaft and 4 bolts on the tailshaft housing and your there. Be sure to retrieve all of the broken pieces of the old snap-ring. I wonder how many transfer cases have been condemed because of this $5.60 snap-ring.