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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 20 (Manual Transmission - NV 3500 - Service) >> Diagnostic Information and Procedures >> Transmission Clunk on Acceleration or Deceleration >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The numbers below refer to step numbers on diagnostic table.

  1. 7:  This step inspects for transfer case causing clunk. Shift transfer case into another mode. If transmission is causing clunk, there will not be a change.
Transmission Clunk on Acceleration or Deceleration

Step Action Yes No
DEFINITION: A clunk is heard and/or felt on acceleration or deceleration.
1 Did you review the Symptoms - Manual Transmission, and perform the necessary inspections? Go to Step 2  Go to Symptoms - Manual Transmission 
2 Inspect the engine mounts for being loose or damaged. Refer to Engine Mount Inspection (4.3L) or Engine Mount Inspection (4.8L, 5.3L & 6.0L).
Did you find and repair the condition?
Go to Step 10  Go to Step 3 
3 Inspect the transmission mounts for being loose or damaged. Refer to Transmission Mount Replacement - Rear .
Did you find and repair the condition?
Go to Step 10  Go to Step 4 
4 Inspect the transmission to engine fasteners for being loose or missing. Refer to Fastener Tightening Specifications .
Did you find and repair the condition?
Go to Step 10  Go to Step 5 
5 Inspect the driveline for causing the clunk. Refer to Diagnostic Starting Point - Propeller Shaft .
Did you find and repair the condition?
Go to Step 10  Go to Step 6 
6 Is the vehicle equipped with a transfer case? Go to Step 7  Go to Step 9 
7 Shift the transfer case in 4HI.
Is the clunk still present?
Go to Step 9  Go to Step 8 
8 Inspect the transfer case for causing the clunk. Refer to Diagnostic Starting Point - Transfer Case .
Did you find and repair the condition?
Go to Step 10  Go to Step 9 
9
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Disassemble the transmission. Refer to TRANSMISSION DISASSEMBLE .
  3. Inspect the following transmission components that maybe causing the clunk:
    • The mainshaft bearing preload
    • The countershaft bearing preload
    • Worn speed gear teeth
    • Worn countershaft gear teeth
    • Worn synchronizer sleeve to hub
    • Worn thrust washers and thrust surfaces on the speed gears or mainshaft
Did you find and repair the condition?
Go to Step 10  Go to Diagnostic Aids 
10 Operate the system in order to verify the repair.
Did you correct the condition?
System OK Go to Step 1