Inspect And Repair Sea Water Pump (6068SFM50/75 and 6068AFM75)

NOTE: 6068SFM50 engine is illustrated. Procedures are the same for 6068SFM75/AFM75 engines, except the 6068SFM50 pump has a shaft key while the SFM75/AFM75 pump has a splined shaft.

1. 
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   Remove Cover Plate

   
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   Remove and Inspect Components

   
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   Inspect Sea Water Pump Impeller

   A - Cover Plate

   B - Impeller

   C - Shaft Key

   D - O-Ring

   E - Cam Plate

   Close sea cocks and drain sea water system.

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2. Remove cover plate (A) from sea water pump.

3. NOTE: Special impeller puller tool is provided with minor and major sea water pump rebuild kits. If tool is not available, the impeller can normally be removed by using two pair of pliers to grip impeller vanes on opposite sides of impeller. Rotating the pump shaft by hand may help free the impeller. Petroleum based lubricants can cause the impeller to swell, and are not recommended to free a stuck impeller.

   Remove impeller (B) and shaft key (C) (6068SFM50 only) from pump housing.

4. Remove O-ring (D).

5. Inspect cam plate (E) for evidence of heavy pitting or wear. Replace as needed.

6. Inspect impeller for damages such as tears, stress cracks, excess abrasions on vane ends, or chunks of material missing. Impellers that are run dry will overheat and fail the impeller blades at the root. Impellers that swell and stick, fail the impeller in the middle of the blade. If impeller replacement is necessary, order an impeller repair kit.

   IMPORTANT: If impeller has chunks of material missing, the heat exchanger, aftercooler, marine gear oil cooler and any other circuit that are cooled by raw water should be thoroughly cleaned and flushed.

7. Install shaft key (C) (6068SFM50 only) on shaft.

8. IMPORTANT: Petroleum based lubricants can cause the impeller to swell, and are not recommended to lubricate the impeller before installation.

   Lubricate new impeller blades with a non-petroleum based lubricant such as silicone or soapy water. Install impeller using a twisting motion and be sure the impeller blades are bent in the same direction as they were upon removal to prevent damage at startup. Rotate impeller on shaft to align keyways/splines and slide the impeller onto the shaft.

9. Using a new O-ring (D), install cover plate and tighten cap screws with washers securely.

10. Install sea water pump and tighten cap screws to 73 N˙m (54 lb-ft).

11. Connect sea water inlet and outlet tubes. Tighten mounting cap screws evenly until secure.

12. Replace O-rings on oil tubes and install oil filter housing and oil tubes. Tighten mounting cap screws to 35 N˙m (26 lb-ft).

13. Open sea cocks, start engine and check pump operation.