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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 601 (Transfer Case - NVG 136-NP4 (One Speed Automatic)) >> Repair Instructions >> Cleaning and Inspection

Cleaning and Inspection

WARNING: This page is about a different car, the 2001 Oldsmobile Bravada, 2001 GMC Safari, and 2001 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
  1. Clean the bearings.

    Remove all old lubricant and dirt.

  2. Clean the shafts.
  3. Clean the sprockets.
  4. Clean the chain.
  5. Clean the oil feed ports and the channels in each case half.

    Apply compressed air to each oil feed port and channel and channel in order to remove any obstructions or cleaning solvent residue.

  6. Clean all mating and sealing surfaces.
  7. Inspect the bearings and the thrust washers for the following conditions:
    • Spalling
    • Brinneling
    • Corrosion
  8. Inspect the gear teeth for the following conditions:
    • Excessive wear or damage
    • Spalling
    • Cracks
    • Corrosion
  9. Inspect the gear splines for the following conditions:
    • Excessive wear
    • Spalling
    • Cracks
    • Twist
    • Corrosion
  10. Inspect the shaft splines for the following conditions:
    • Excessive wear
    • Spalling
    • Cracks
    • Distortion
    • Corrosion
  11. Inspect the retainer rings for the following conditions:
    • Excessive wear
    • Distortion
    • Damage
  12. Inspect the case halves for the following conditions:
    • Damaged or warped mating surfaces
    • Cracks
    • Porosity
    • Damaged thread holes
  13. Inspect the synchronizer stop rings for the following conditions:
    • Cracks
    • Chips
    • Spalling
    • Excessive wear
  14. Inspect the synchronizer hub and sleeve for the following conditions:
    • Cracks
    • Chips
    • Spalling
    • Excessive wear
  15. Inspect the pads on the mode fork and on the range fork for the following conditions:
    • Wear
    • Distortion
  16. Inspect the oil pump gears and the case (DO NOT disassemble the oil pump) for the following conditions:
    • Wear

      (Replace the complete assembly if there is excessive wear.)

    • Spalling
    • Cracks
    • Damage
  17. Inspect the following components for excessive wear:
    • The input gear
    • The planetary carrier
    • The range shift hub tooth chamfers