Transfer Case Clunk in 4HI

WARNING: This page is about a different car, the 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Problem	Action
DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer case while in the 4HI range only. Review the Symptoms - Transfer Case and perform the necessary inspections.
Incorrect fluid level or incorrect fluid	Inspect the transfer case for the correct fluid level. Refer to Transfer Case Fluid Replacement (TrailBlazer, Envoy, Rainier, Bravada) or Transfer Case Fluid Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV) . Fill the transfer case to the correct fluid level, if required. Inspect the transfer case for the correct type of fluid. Flush the transfer case and fill with the correct fluid, if required.
Worn high speed teeth on the range collar	Inspect for worn high speed teeth on the range collar. Refer to Cleaning and Inspection in Transfer Case - NVG 226-NP8 Unit Repair.
Worn or missing input gear thrust washers	Inspect for worn or missing input gear thrust washers. Refer to Cleaning and Inspection in Transfer Case - NVG 226-NP8 Unit Repair.