4x4 Rattle: Transmission, Transfer Case, Neither, or Both.
 

I have a 2004 S-Blazer 4x4, 4.3L, Auto, w/94K miles. The transfer case is the NP8 / 236C with the 4 buttons on the dash.

There is no drive line noise when cold but after driving about 2 miles there is a rattle that sounds like it is comming from the transfer case. I had the lubricant changed in the transfer case (Auto-Trak II) but still have the rattle. It sounds like a skid plate vibration but I don't think so. I can duplicate the rattle by putting the transmission in Drive and giving it a little gas while apply the brakes. It will not do this when the vehicle is cold / parked for several hours.

Could it be a transmission bearing noise? Last month I had to have the bearings in the G80 rear end replaced. They were self destructing probable due to water intrusion.

Also, I brought 3 quarts of Auto-Trak II transfer case lube to the shop and they had the "oil-change guy" drain and refill. Without even knowing the capacity of the case, he dumped all 3 quarts of fluid in. Is that a potential problem?

Thanks in advance,

cuda

Could be an exhaust shield making noise. As far as the t-case fluid, just get under there and check it.

Is that a problem??? It should not be possible to put that much in there unless you directly connect the bottle to the fill port so as to prevent the fluid from coming out... I believe the capacity of the 236 is just under 2 qts.

As far as the sound, if you are not moving, nothing inside the transfer case is moving either. I too would suspect a heat shield or skid plate.