Transfer Case Clunk in 4HI

WARNING: This page is about a different car, the 2006 GMC Yukon XL, 2006 GMC Yukon, 2006 Chevrolet Tahoe, 2006 Chevrolet Suburban, and 2006 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Cause	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 . Inspect the transfer case for the correct type of fluid. Flush the transfer case and fill with the correct fluid, if required. Refer to Transfer Case Fluid Replacement .
Worn high speed teeth on the range sleeve	Inspect for worn high speed teeth on the range sleeve. Refer to Cleaning and Inspection in Transfer Case - NVG 246-NP8 Unit Repair. Replace the range collar if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 246-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 246-NP8 Unit Repair.
Rear output shaft bearing outer retaining ring	Inspect for the following conditions: Properly installed rear output shaft bearing retaining ring Excessive wear or damage to the retaining ring groove in the rear case half Refer to Cleaning and Inspection in Transfer Case - NVG 246-NP8 Unit Repair. Repair or replace the following components if found faulty: Replace the rear output shaft bearing outer retaining ring. Replace the rear case half if the retaining ring groove is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble in Transfer Case - NVG 246-NP8 Unit Repair.