Chevrolet Silverado / GMC Sierra. Service manual — part 2804

Fig. 1: Case Components
Courtesy of GENERAL MOTORS CORP.

Callout

Component Name

1

Adapter Stud

2

Front Case Half

3

Location Pin

3

Location Pin

4

Rear Output Shaft Bushing

5

Rear Output Shaft Seal

6

Shipping Seal

7

Fill Plug

8

Case Half Bolt

9

Wiring Harness Bracket

10

Drain Plug

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 2: Internal Components
Courtesy of GENERAL MOTORS CORP.

11

Rear Case Half

12

Front Output Shaft Seal

13

Vent

14

Input Shaft Seal

Callout

Component Name

1

Input Gear Bearing

2

Input Shaft

3

Drive Sprocket Bushing

4

Drive Sprocket

5

Drive Chain

6

Front Sun Gear

7

Planetary Differential Assembly

8

Rear Sun Gear Thrust Washer

9

Rear Sun Gear

10

Input Shaft Rear Support Bushing

11

Rear Output Shaft

12

Rear Output Shaft Bearing Outer Retaining Ring

13

Rear Output Shaft Bearing

14

Rear Output Shaft Bearing Retaining Ring

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

DIAGNOSTIC INFORMATION AND PROCEDURES

DIAGNOSTIC STARTING POINT - TRANSFER CASE

Begin the system diagnosis by reviewing the Symptoms - Transfer Case. The Symptoms -
Transfer Case will provide the following information:

The required visual/physical inspections

The list of symptoms

Use the Strategy Based Diagnosis in order to identify the correct procedure for diagnosing the
system.

SYMPTOMS - TRANSFER CASE

Strategy Based Diagnostics

Review the system operation in order to familiarize yourself with the system functions. Refer to
Transfer Case Description and Operation.

Visual/Physical Inspection

Inspect the easily accessible or visible system components for obvious damage, or for
conditions which could cause the symptom.

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

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:

Transfer Case Popping Noise

Transfer Case Whine or Rumble Noise

Transfer Case Growl or Grinding Noise

15

Front Output Shaft Rear Bearing

16

Driven Sprocket

17

Front Output Shaft Cup Plug

18

Front Output Shaft

19

Front Output Shaft Front Bearing

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Transfer Case Shudder or Binding

Transfer Case Clunk during Acceleration and Deceleration

Transfer Case Leak Diagnosis

TRANSFER CASE POPPING NOISE

TRANSFER CASE WHINE OR RUMBLE NOISE

TRANSFER CASE GROWL OR GRINDING NOISE

Cause

Correction

DEFINITION: A faulty internal transfer case component that causes a popping noise in the
transfer case.
Review the Symptoms - Transfer Case and perform the necessary inspections.
Chain jump

Replace the chain and sprockets. Refer to Transfer Case
Disassemble and Transfer Case Assemble.

Replace the shaft bearings. Refer to Transfer Case
Disassemble and Transfer Case Assemble.

Inspect for damaged components caused by metal debris.
Refer to Transfer Case Disassemble and Transfer
Case Assemble.

Cause

Correction

DEFINITION: A faulty internal transfer case component that causes a whine noise in the
transfer case.
Review the Symptoms - Transfer Case and perform the necessary inspections.
Faulty bearings

1. Inspect all of the bearings and journals. Refer to

Transfer Case Cleaning and Inspection.

2. Replace any faulty bearings, and any components with

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

Cause

Correction

DEFINITION: A faulty internal transfer case component that causes a growl or grinding
noise in the transfer case while the vehicle is turning.
Review the Symptoms - Transfer Case and perform the necessary inspections.
Planetary differential

1. Inspect the planetary differential pinion gears for the

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado