Chevrolet Silverado / GMC Sierra. Service manual — part 2930

High/low shift fork pads

High/Low Shift Components Cleaning and
Inspection.

2. Replace the fork pads if worn. Refer to Transfer Case

Disassemble and Transfer Case Assemble.

Faulty high/low shift fork

1. Inspect the high/low shift fork for being damaged. Refer

to High/Low Shift Components Cleaning and
Inspection.

2. Replace the high/low shift fork if faulty. Refer to

High/Low Shift Fork Replacement.

High/low shift fork spring
assembly

1. Inspect the high/low shift fork spring assembly for the

following conditions:

Worn high/low shift fork pin

Worn cam

Broken spring

Refer to High/Low Shift Components Cleaning
and Inspection .

2. Replace the following components if found faulty:

The high/low shift fork spring assembly

The high/low shift fork pin

Refer to High/Low Shift Fork Replacement .

Faulty high speed teeth on
the high/low clutch

1. Inspect for the following conditions:

The input shaft high speed engagement teeth for
wear or damage

The engagement teeth on the high/low clutch for
wear or damage

Refer to Front Output Shaft and Input Shaft
Cleaning and Inspection and High/Low Shift
Components Cleaning and Inspection .

2. Replace the high/low clutch if the teeth are faulty. Refer

to Transfer Case Disassemble and Transfer Case
Assemble.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

TRANSFER CASE LEAK DIAGNOSIS

3. Replace the input shaft if the engagement teeth are faulty.

Refer to Transfer Case Disassemble and Transfer
Case Assemble.

High/low planetary carrier
assembly

1. Inspect the high/low planetary carrier for the following

conditions:

Low speed engagement teeth worn or damaged

Cracked carrier housing

Planetary gear needle bearings worn

Planetary gears broken or damaged teeth

Planetary gears seized or binding

Refer to High/Low Planetary Carrier Cleaning
and Inspection .

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

above conditions exist. Refer to Transfer Case
Disassemble and Transfer Case Assemble.

Input shaft pilot bearing
assembly

1. Inspect the bearing in the input shaft and the rear output

shaft journal for excessive wear. Refer to Front Output
Shaft and Input Shaft Cleaning and Inspection and

Rear Output Shaft Cleaning and Inspection

.

2. Replace the bearing and the rear output shaft if faulty.

Refer to Input Shaft Pilot Bearing Replacement
(Light Duty) or Input Shaft Pilot Bearing
Replacement (Heavy Duty and Super Heavy Duty)
and Transfer Case Assemble.

Input shaft

1. Inspect the input shaft for broken or damaged teeth.

Refer to Front Output Shaft and Input Shaft
Cleaning and Inspection.

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

Disassemble and Transfer Case Assemble.

Cause

Correction

DEFINITION: A visible indication of an external fluid leak from the transfer case.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Review the Symptoms - Transfer Case and perform the necessary inspections.

Drain plug or fill plug leak

1. Inspect for the correct sealer and amount of sealer on the

plugs. Refer to Sealers, Adhesives, and Lubricants.

2. Correctly install the plugs. Refer to Transfer Case

Fluid Replacement.

Access hole plugs leaking

Replace the access hole plugs or seal with room temperature
vulcanizing (RTV) sealant.

Vehicle speed sensor (VSS)
leaking

1. Remove the VSS. Refer to Vehicle Speed Sensor

Replacement.

2. Inspect the VSS for the following conditions:

Cross threaded

Cut or damaged VSS O-ring seal

VSS over tightened causing deformation in the VSS

3. Replace the VSS O-ring seal if faulty.

4. Replace the VSS if faulty.

Rear output shaft seal
leaking

1. Inspect for the following conditions:

Overfilled or improper transfer case fluid

Blocked vent

Seal improperly installed, worn, or damaged

Seal bore damaged or cracked

Rear output shaft bushing for excessive wear

Slip yoke seal surface for wear or pitting

2. Repair or replace the following components if found

faulty:

Adjust or replace the transfer case fluid. Refer to
Transfer Case Fluid Replacement .

Clean or properly route the vent hose.

Replace the rear output shaft seal. Refer to Rear
Output Shaft Seal Replacement .

Replace the rear case half if the seal bore is
damaged. Refer to Transfer Case Disassemble
and Transfer Case Assemble .

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

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Replacement .

Replace the slip yoke if the surface could cause
leakage. Refer to One-Piece Propeller Shaft
Replacement or Two-Piece Propeller Shaft
Replacement .

Front output shaft seal
leaking

1. Inspect for the following conditions:

Overfilled or improper transfer case fluid

Blocked vent

Seal improperly installed, worn or damaged

Seal bore damaged or cracked

Leaking cup plug in the front output shaft

2. Repair or replace the following components if found

faulty:

Adjust or replace the transfer case fluid. Refer to
Transfer Case Fluid Replacement .

Clean or properly route the vent hose.

Replace the front output shaft seal. Refer to Front
Output Shaft Seal Replacement .

Replace the front case half if the seal bore is
damaged. Refer to Transfer Case Disassemble
and Transfer Case Assemble .

Replace the cup plug in the front output shaft if it is
leaking. Refer to Transfer Case Disassemble and
Transfer Case Assemble .

2/4 wheel drive actuator
seal leaking

Replace the actuator seal. Refer to Transfer Case Two/Four
Wheel Drive Actuator Replacement.

Leaking at the vent pipe

Transfer case overfilled

Inspect for the correct transfer case fluid level. Refer to
Transfer Case Fluid Replacement.

Inspect for a damaged or missing vent pipe.

Replace a damaged or missing vent and seal the vent pipe
with the correct sealer. Refer to Transfer Case
Assemble.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado