GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2003 🢒 Yukon - 4WD 🢒 Driveline/Axle 🢒 Transfer Case - BW 4473-NP3 🢒 Transfer Case Cleaning and Inspection

Front Case Half

    Object Number: 823245 Size: SH
  1. Clean the front case half in cleaning solvent and air dry.
  2. Remove the metal shavings from the case half bolt holes.

    3. Notice: Refer to Machined Surface Damage Notice in the Preface section.

  3. Remove the sealer from the case sealing surfaces.
  4. Inspect the case for being broken or cracked.
  5. Inspect the front output shaft front bearing bore (5) for the following conditions:
    6. • Spun bearing
    • Cracks
  6. Replace the front case half if any of the above is found.
  7. Inspect the sealing surfaces (2) for damage.
  8. Repair small scratches or nicks with a soft stone.
  9. Inspect the front case to transmission case mounting surface for damage.
  10. Inspect the case threaded bolt holes (3) for damage.
  11. Repair any damaged threads.
  12. Inspect the transmission to transfer case studs (1) for damage.
  13. Replace any damaged studs. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  14. Inspect the location pins (4 and 7) for being loose or missing.
  15. Repair or replace any damaged location pins.
  16. Inspect the input shaft bushing (6) for the following conditions:
    17. • Excessive wear
    • Scoring
  17. Inspect the front output shaft front bearing for the following conditions:
    18. • Roughness
    • Brinelling
    • Pitting
  18. Replace the bearings if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Rear Case Half

    Object Number: 823246 Size: SH
  1. Clean the rear case half in cleaning solvent and air dry.

    2. Notice: Refer to Machined Surface Damage Notice in the Preface section.

  2. Remove the sealer from the case sealing surfaces.
  3. Inspect the case for being broken or cracked.
  4. Replace the case if it is broken or cracked.
  5. Inspect the sealing surfaces (1) for damage.
  6. Repair small scratches or nicks with a soft stone.
  7. Inspect the case threaded bolt holes for damage.
  8. Repair any damaged threads.
  9. Inspect the front output shaft rear bearing bore (2) for the following conditions:
    10. • Spun bearing
    • Cracks
  10. Inspect the rear output shaft rear bearing bore (5) for the following conditions:
    11. • Spun bearing
    • Cracks
  11. Replace the case if the bearing has spun. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  12. Inspect the retaining ring (4) for the rear output shaft rear bearing for being bent or twisted.
  13. Replace a faulty retaining ring.
  14. Inspect the rear output shaft bushing (3) for scoring or wear.
  15. Replace the case if the rear output shaft bushing is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Rear Output Shaft

    Object Number: 823248 Size: SH
  1. Clean the rear output shaft with the input shaft rear support bearing and the rear output shaft bearing in cleaning solvent.
  2. Air dry and ensure all solvent is removed from the bearings.
  3. Inspect the speed reluctor wheel (1) for damage.
  4. Replace the speed reluctor wheel if faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  5. Inspect the rear output shaft bearing (2) for the following conditions:
    6. • Scoring
    • Pitting
    • Brinelling
    • Excessive wear
  6. Replace the rear output shaft bearing (2) if it is faulty. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  7. Inspect the input shaft rear support bearing (3) for the following conditions:
    8. • Scoring
    • Pitting
    • Brinelling
    • Excessive wear
  8. Replace the input shaft rear support bearing (3) if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  9. Inspect the rear output shaft splines (4) for wear or damage.
  10. Inspect the rear output shaft bearing area for a spun bearing.
  11. Replace the rear output shaft if any of the above conditions are found.

Input Shaft

    Object Number: 823249 Size: SH
  1. Clean the input shaft in cleaning solvent.
  2. Clean the input shaft oil galleries (3) and air dry.
  3. Inspect the oil scoop (2) for damage.
  4. Replace the oil scoop if it is damaged.

    5. Important: Do not attempt to smooth any roughness in the bearing journals.

  5. Inspect the journals on the input shaft for the following conditions:
    6. • The input gear bushing journal (1)
    • The sun gear bushing journal (6)
    • The input gear rear support bearing journal (5)
       - Scoring
       - Pitting
       - Brinelling
       - Excessive wear
  6. Inspect the input shaft internal input splines (7) and the planetary carrier splines (4) for damage or excessive wear. Witness marks are normal.
  7. Replace the input shaft if any of the above conditions are found.

Front Output Shaft

    Object Number: 819682 Size: SH
  1. Clean the front output shaft in cleaning solvent and air dry.
  2. Inspect for spun bearings at the front output shaft bearing areas.
  3. Inspect the front output internal splines and driven gear splines for damage or excessive wear.
  4. Replace the front output shaft if it is damaged.
  5. Inspect the cup plug in the front output shaft for leaking.
  6. Replace the cup plug if it is leaking. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Planetary Carrier

    Object Number: 823250 Size: SH
  1. Clean the planetary carrier in cleaning solvent. Do not disassemble the planetary carrier.
  2. Air dry, and ensure all cleaning solvent is removed from the bushings in the pinion gears (3). Do not spin the pinion gears with compressed air.
  3. Inspect the pinion gears for excessive looseness because of wear at the bushings or the shafts.
  4. Inspect the pinion gears for chipped teeth.
  5. Inspect the pinion gears for debris embedded in the root of the teeth.
  6. Inspect the planetary assembly for cracks at the web (1) of the housing.
  7. Inspect the thrust washer surface (2) for scoring or excessive wear.
  8. Replace the planetary carrier if any of the above conditions are found.
  9. Inspect the planetary carrier thrust washers for excessive wear or scoring.
  10. Replace the thrust washers if they are faulty.

Viscous Coupling

    Object Number: 823251 Size: SH
  1. Inspect the viscous coupling for leaking at the ball (1) in the housing. A black liquid would be visible if it is leaking.
  2. Replace the viscous coupling if it is leaking.
  3. Inspect for excessive worn splines (2).
  4. Replace the viscous coupling if the splines are faulty.

Drive Chain and Sprockets

    Object Number: 823252 Size: SH
  1. Clean the drive chain (2), drive sprocket (3), and driven sprocket (1) in cleaning solvent and air dry.
  2. Inspect the drive chain (2) for the following conditions:
    3. • Loose link pins
    • Binding or stiff links
    • Debris embedded in the links
    • Worn teeth surfaces
  3. Replace the chain if any of the above conditions are found.
  4. Inspect the driven sprocket (1) and the drive sprocket (3) for the following conditions:
    5. • Chipped teeth
    • Excessive worn gear surfaces
    • Slight wear marks are normal.
    • Debris embedded in the root of the teeth
  5. Replace the sprockets if any of the above conditions are found. The chain and sprockets may be replaced separately.

Sun Gear

    Object Number: 823253 Size: SH
  1. Clean the sun gear in cleaning solvent and air dry.
  2. Inspect the teeth on sun gear (1) for the following conditions:
    3. • Chipped teeth
    • Excessive worn gear surfaces
    • Slight wear marks are normal.
    • Debris embedded in the root of the teeth
  3. Inspect the input shaft bushing (2) for excessive wear or scoring. The bushing is only serviced with the gear.
  4. Replace the sun gear if they are faulty.

Annulus Gear

    Object Number: 823254 Size: SH
  1. Clean the annulus gear in cleaning solvent and air dry.
  2. Inspect the annulus gear for the following conditions:
    3. • Chipped teeth
    • Damage or excessive wear
    • Witness marks are normal.
    • Debris embedded in the root of the teeth
  3. Replace the annulus gear if any of the above conditions are found.