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SERIES 638 WATER PUMP

The centrifugal-type water pump circulates the engine coolant through the cooling system. ‪

Repair or Replacement of Water Pump

To determine if repair or replacement is necessary, perform the following procedure. See Figure 27215 . ‪

Flowchart for Repair or Replacement of Water Pump

Removal of Water Pump

Perform the following to remove water pump: ‪

Do not remove the pressure control cap from the radiator or attempt to drain the coolant until the engine has cooled. Once the engine has cooled, use extreme caution when removing the cap. The sudden release of pressure from a heated cooling system can result in a loss of coolant and possible personal injury (scalding, eye injury, etc.) from the hot liquid. ‪

  1. Drain cooling system.
  2. Secure water pump pulley with a strap belt.
  3. Loosen fan clutch nut from water pump shaft.

    Note: The fan clutch nut is left-hand threaded.

  4. Remove fan and clutch assembly.
  5. Loosen alternator and remove alternator belts.
  6. Remove water pump pulley retaining bolts.
  7. Loosen bypass hose clamps.
  8. Remove static fill hose.
  9. Disconnect weep hole hose from water pump.
  10. Remove four water pump bolts, gasket, and water pump from the cylinder block and from the bypass hose.

    Note: Do not remove bypass hose.

Cleaning of Water Pump

Clean the water pump as follows: ‪

  1. Remove all traces of gasket material from the cylinder block.
  2. Clean the water pump to cylinder block surface with clean fuel oil.

    To avoid personal injury when blow drying, wear adequate eye protection (safety glasses or face plate) and do not exceed 276 kPa (40 lb/in. 2 ) air pressure. ‪

  3. Dry with compressed air.

Installation of Water Pump

Perform the following to install water pump: ‪

  1. Install water pump with new gasket to cylinder block and attach bypass hose. Torque bolts to 27 N m (20 lb ft).
  2. Connect weep hole hose to water pump.
  3. Connect static fill hose.
  4. Tighten bypass hose clamps.
  5. Install water pump pulley retaining bolts. Torque bolt to 27 N m (20 lb ft).
  6. Install alternator belts and adjust belt tension.
  7. Install fan and clutch assembly to water pump.
  8. Secure water pump pulley with a strap belt and tighten fan clutch nut. Torque nut to 27 N m (21 lb ft).
  9. Refill cooling system.
  10. Run the engine to verify repair.