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The centrifugal-type water pump circulates raw water through the charge air cooler (CAC) on keel-cooled marine engines. The drive end of the pump shaft is supported by a sealed double-row combination radial and thrust ball bearing. The pump shaft serves as the inner race of the bearing. ‪

The pump is mounted to the rear end of the gear case on the intake side of the engine. The drive coupling, pressed on the end of the pump shaft, has an integral oil thrower that shrouds the flange end of the pump body and deflects the oil away from the bearing. See Figure 36015 . ‪

1. To Charge Cooler ‪

5. Bolt ‪

2. Hose ‪

6. Water Pump ‪

3. Pump Cover ‪

7. Inlet Flange ‪

4. Drain Cock ‪

8. Clamp ‪

CAC Water Pump Mounting

Note: The high capacity water pump has a shaft bearing assembly, unitized seal assembly, drive coupling, and ceramic insert.

Replacement of CAC Water Pump

To determine if repair or replacement is necessary, perform the following procedure. See Figure 36014 . ‪

Flowchart for Repair or Replacement of CAC Water Pump

Removal of CAC Water Pump

Remove the water pump as follows: ‪

  1. Drain the raw water from the charge air cooler system and open the drain cock in the pump body.
  2. Loosen the hose clamps and slide the water pump inlet hose back onto the charge cooler inlet pipe.
  3. Remove the nuts and bolts that attach the pump to the raw water supply pipe.
  4. Remove the bolts and lock washers that attach the pump mounting flange to the drive assembly.
  5. Withdraw the pump and remove the gasket.

Disassembly of CAC Water Pump

Disassemble the water pump as follows: ‪

  1. Remove the pump cover and gasket.

    Note: Clean any corrosion from around the impeller and shaft before separating the shaft and bearing assembly from the impeller, seal, and pump body.


    Shaft bearing damage may occur on the water pump if an excessive thrust load is applied to the bearing assembly during pump disassembly for seal replacement. For this reason DDC recommends replacing the shaft and bearing assembly of the water pump whenever the seal is replaced and /or at time of water pump overhaul. ‪

  2. Support the pump on its mounting flange in an arbor press. See Figure 27988 . Place a short steel rod on the end of the shaft and press the shaft and bearing assembly from the impeller, seal, and pump body.

    1. Steel Bar ‪

    3. Shaft and Bearing Assembly ‪

    2. Impeller ‪

    Pressing Pump Shaft from Impeller

  3. Remove the impeller and seal assembly from the pump body.
  4. Remove the pump drive coupling from the shaft with tool J 1930 . See Figure 27989 .

    1. Steel Bar ‪

    3. Steel Rod ‪

    2. Drive Coupling ‪

    Removing Pump Drive Coupling from Shaft

Inspection of CAC Water Pump

Inspect the water pump as follows: ‪

  1. Visually inspect the parts for cracks, wear, or other damage.
    1. If parts are cracked, worn, or other damage is evident, replace damaged or worn parts.
    2. If no damage is found, reuse remaining components.

Assembly of CAC Water Pump

Assemble the water pump as follows: ‪


To avoid possible engine damage, the sealed pump shaft bearing must not be immersed in a cleaning fluid, since dirt may be washed in and fluid cannot entirely be removed. ‪

  1. Clean all of the parts, except the shaft and bearing assembly.
  2. Replace the shaft and bearing assembly and the seal assembly.
  3. Support the pump body on the bed of an arbor press, impeller end down. Insert the long (impeller) end of the shaft and bearing assembly into the body.


    The shaft and bearing assembly will be damaged if it is installed by applying pressure to the shaft or inner race. ‪

  4. Press against the outer race of the bearing until the bearing is flush with the end of the pump body.
  5. To eliminate possible coolant leakage, apply a light coat of Loctite 290 sealant to the outside diameter of the new seal.
  6. Invert the pump so that the impeller end faces up. See Figure 29820 .

    1. Shaft Support ‪

    2. Impeller ‪

    Installing Water Pump Impeller

  7. With the pump body and bearing shaft properly supported, place a fresh unitized seal over the shaft. Tool J 38858 must be used to set the seal to its proper installed height. Using tool J 38858 , press the seal into place.
  8. Ensure the mating surfaces of the water seal and impeller are free of dirt, metal particles, and oil film.


    The bearing shaft end must be supported during this operation. Do not press against the outer race of the bearing. This can damage the bearing. ‪

  9. Support the bearing end of the shaft on the bed of an arbor press. Using tool J 22347 , press the impeller onto the shaft. The distance between the end of the shaft and the face of the impeller hub is 0.0078 0.083 mm (0.031 - 0.033 in.).
  10. Invert the pump. With the impeller end of the shaft properly supported on the arbor press, press the drive coupling onto the shaft until it is flush with the end of the shaft.

    Note: When installed, the drive coupling must hold 41 Nm (30 lbft) minimum torque.

  11. Rotate the shaft by hand to ensure the rear faces of the impeller blades do not rub against the pump body.
  12. If previously removed, install the drain cock in the pump body.

Installation of CAC Water Pump

Install the water pump as follows: ‪

  1. Ensure the intermediate shaft coupling is secure.
    1. If it was previously removed, insert the splined end of the coupling into the mating splines in the drive assembly.
    2. Install the bolts and lockwashers, then draw the coupling in place with the bolts.
    3. Torque the bolts to 20 26 Nm (15 19 lbft).
  2. Slide the charge cooler inlet hose in place and secure it with the hose clamps.
  3. Close the pump drain cock.
  4. Remove and check the condition of the raw water pump electrodes (zincs). Replace if required.
  5. Fill the raw water cooling system.


    Diesel engine exhaust and some of its constituents are known to the State of California to cause cancer, birth defects, and other reproductive harm.

    • Always start and operate an engine in a well ventilated area.
    • If operating an engine in an enclosed area, vent the exhaust to the outside.
    • Do not modify or tamper with the exhaust system or emission control system.
  6. Start the engine and check for leaks.