Chevrolet Silverado / GMC Sierra. Service manual — part 2838

TRANSFER CASE CLUNK IN 2HI ONLY

Input shaft

Excessive wear

Chipped teeth

Metal embedded in the root of the teeth

Refer to Front Output Shaft and Input Shaft
Cleaning and Inspection

3. Replace the input shaft if faulty. Refer to Transfer Case

Disassemble and Transfer Case Assemble.

Thrust washers

1. Inspect for missing or damaged thrust washers for the

input shaft.

2. Inspect the thrust washers for galling.

3. Replace the thrust washers if faulty and the mating

component if damaged. Refer to Transfer Case
Disassemble and Transfer Case Assemble.

High/low internal gear

1. Inspect the high/low internal gear teeth for the following

conditions:

Damage

Chipped teeth

Excessive wear

Metal embedded in the root of the teeth

Refer to Transfer Case Front Half Cleaning and
Inspection .

2. Replace the front case half if the high/low internal gear is

faulty. Refer to Transfer Case Disassemble and
Transfer Case Assemble.

Cause

Correction

DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer
case.
Review the Symptoms - Transfer Case and perform the necessary inspections.

1. Inspect the transfer case for the correct fluid level.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Incorrect fluid level or
incorrect fluid

2. Inspect the transfer case for the correct type of fluid.

Refer to Approximate Fluid Capacities.

3. Flush the transfer case and fill with the correct fluid, if

required. Refer to Transfer Case Fluid Replacement.

Excessive clearance
between the slip yoke and
the rear output shaft

1. Inspect for the following conditions:

Worn slip yoke splines

Worn rear output shaft splines

2. Repair or replace the following components, if faulty:

Replace the slip yoke. Refer to One-Piece
Propeller Shaft Replacement and Two-Piece
Propeller Shaft Replacement .

Replace the rear output shaft. Refer to Transfer
Case Disassemble and Transfer Case Assemble .

Excessive clearance
between the slip yoke and
the rear bushing

1. Inspect for the following conditions:

Worn rear bushing

Worn slip yoke bushing journal

2. Repair or replace the following components, if faulty:

Replace the slip yoke, if required. Refer to One-
Piece Propeller Shaft Replacement or Two-
Piece Propeller Shaft Replacement .

Replace the rear bushing if worn. Refer to
Transfer Case Rear Extension Bushing
Replacement .

Input shaft thrust washers

1. Inspect for worn or missing input shaft thrust washers.

2. Replace the thrust washers as required. Refer to

Transfer Case Disassemble and Transfer Case
Assemble.

Worn high speed teeth on
the high/low clutch

1. Inspect for worn high speed teeth on the high/low clutch.

Refer to High/Low Shift Components Cleaning and
Inspection.

2. Replace the high/low clutch if worn. Refer to Transfer

Case Disassemble and Transfer Case Assemble.

1. Inspect for the following conditions:

Properly installed rear output shaft rear bearing

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

TRANSFER CASE CLUNK IN 4HI

Rear output shaft rear
bearing outer retaining ring

outer retaining ring

Excessive wear or damaged retaining ring groove in
the rear case half

2. Repair or replace the following components if found

faulty:

Properly install a new rear output shaft rear bearing
outer retaining ring.

Replace the rear case half if the retaining ring
groove is excessively worn. Refer to Transfer
Case Disassemble and Transfer Case Assemble .

Cause

Correction

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

1. Inspect the transfer case for the correct fluid level.

2. Inspect the transfer case for the correct type of fluid.

Refer to Approximate Fluid Capacities.

3. Flush the transfer case and fill with the correct fluid, if

required. Refer to Transfer Case Fluid Replacement.

Input shaft thrust washers

1. Inspect for worn or missing input shaft thrust washers.

2. Replace the thrust washers as required. Refer to

Transfer Case Disassemble and Transfer Case
Assemble.

2/4 wheel drive
synchronizer assembly

1. Inspect the synchronizer for the following conditions:

The synchronizer hub internal teeth to rear output
shaft splines for excessive looseness caused by wear

The synchronizer sleeve engagement teeth to the
drive sprocket for wear

Refer to Two/Four Wheel Drive Shift
Components Cleaning and Inspection .

2. Replace the synchronizer assembly if faulty. Refer to

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

TRANSFER CASE CLUNK IN 4LO

Transfer Case Disassemble and Transfer Case
Assemble.

Rear output shaft rear
bearing outer retaining ring

1. Inspect for the following conditions:

Properly installed rear output shaft rear bearing
outer retaining ring

Excessive wear or damaged retaining ring groove in
the rear case half

2. Repair or replace the following components if faulty:

Properly install a new rear output shaft rear bearing
outer retaining ring.

Replace the rear case half if the retaining ring
groove is excessively worn. Refer to Transfer
Case Disassemble and Transfer Case Assemble .

Worn high speed teeth on
the high/low clutch

1. Inspect for worn high speed teeth on the high/low clutch.

Refer to High/Low Shift Components Cleaning and
Inspection.

2. Replace the high/low clutch if worn. Refer to Transfer

Case Disassemble and Transfer Case Assemble.

Cause

Correction

DEFINITION: During acceleration or deceleration, a clunk is heard or felt in the transfer
case while in the 4LO range only.
Review the Symptoms - Transfer Case and perform the necessary inspections.

High/low planetary carrier
assembly

1. Inspect for the following conditions:

Excessively worn planetary gears

The planetary gears loose in the planetary carrier

Excessively worn high/low clutch engagement teeth
on the carrier

Refer to High/Low Planetary Carrier Cleaning
and Inspection .

2. Replace the high/low planetary if any of the above

conditions are found.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado