GM Service Manual Online
For 1990-2009 cars only

Water Pump Cleaning and Inspection C/K

Tools Required

J 41240 Fan Clutch Wrench


    Object Number: 635640  Size: SH
  1. Remove the water pump pulley bolts using the J 41240 in order to prevent water pump pulley rotation.
  2. Remove the water pump pulley.
  3. Inspect the water pump pulley for damage at the belt contact area and the pulley-to-water pump mounting surface.

  4. Object Number: 635691  Size: SH

    Important: Do not immerse the water pump in solvent. The solvent may enter the water pump's permanently lubricated bearings and cause premature bearing failure.

  5. Clean all excess dirt and debris from the water pump housing.
  6. Inspect the water pump for the following:
  7. • Leakage at the hose fitting (1)
    • Leakage at the water pump weep hole (3)
    • A stain around the weep hole is acceptable. If leakage occurs (dripping) with the engine running and the cooling system pressurized, replace the water pump.
    • Gasket sealing surfaces (2) for excessive scratches or gouging
    • Restrictions within the internal coolant passages (6)
    • Excessive side-to-side play in the pulley shaft (5)
    • If the shaft end play exceeds 0.381 mm (0.015 in), replace the water pump.
    • Rotate the pump shaft by hand and inspect for roughness of operation
       - If the hub wobbles, is noisy or feels rough when rotated, replace the water pump.
       - The shaft and fan hub must turn straight and smoothly.
    • Damage to threaded bolt holes (4)
    • Damage to the fan clutch mounting threads (5)

    Object Number: 635640  Size: SH
  8. Install the water pump pulley.
  9. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  10. Install the water pump pulley bolts using the J 41240 in order to prevent water pump pulley rotation.
  11. Tighten
    Tighten the water pump pulley bolts to 25 N·m (19 lb ft).

Water Pump Cleaning and Inspection G/C3500HD/Medium Duty

Tools Required

J 41240 Fan Clutch Wrench


    Object Number: 635640  Size: SH
  1. Remove the water pump pulley bolts using the J 41240 in order to prevent water pump pulley rotation.
  2. Remove the water pump pulley.
  3. Inspect the water pump pulley for damage at the belt contact area and the pulley-to-water pump mounting surface.

  4. Object Number: 635719  Size: SH

    Important: Do not immerse the water pump in solvent. The solvent may enter the water pump's permanently lubricated bearings and cause premature bearing failure.

  5. Clean all excess dirt and debris from the water pump housing.
  6. Inspect the water pump for the following:
  7. • Leakage at the hose fitting (1)
    • Leakage at the water pump weep hole (3)
    • A stain around the weep hole is acceptable. If leakage occurs (dripping) with the engine running and the cooling system pressurized, replace the water pump.
    • Gasket sealing surfaces (2) for excessive scratches or gouging
    • Restrictions within the internal coolant passages (4)
    • Excessive side-to-side play in the pulley shaft (5)
    • If the shaft end play exceeds 0.381 mm (0.015 in), replace the water pump.
    • Rotate the pump shaft by hand and inspect for roughness of operation
       - If the hub wobbles, is noisy, or feels rough when rotated, replace the water pump.
       - The shaft and fan hub must turn straight and smoothly.
    • Damage to threaded bolt holes (6)
    • Damage to the fan clutch mounting threads (5)

    Object Number: 635640  Size: SH
  8. Install the water pump pulley.
  9. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  10. Install the water pump pulley bolts using the J 41240 in order to prevent water pump pulley rotation.
  11. Tighten
    Tighten the water pump pulley bolts to 25 N·m (19 lb ft).