Noises from your Cherokee's transfer case are almost always indicative of a problem. Whining, clunking, popping or roaring can warn of issues such as low fluid, a broken chain or worn U-joints.
A frequent cause of transfer case whine is lack of fluid. The fluid in the transfer case is there to cool it and lubricate it. Low fluid levels cause friction, which creates heat and eventually destroys the transfer case.
Not all transfer cases use a chain, but all Jeep Cherokee units do. Some cases on heavy-duty trucks are gear-driven only. If the chain in your Jeep's transfer case stretches or breaks, it will definitely make noise and will need to be rebuilt.
A worn U-joint will cause vibrations in the drive line, and it may sound like they are coming from the transfer case. Inspect the U-joints on both front and rear drive shafts to ensure they are in good condition before making other costly repairs.
