9. Cooling Water System
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9.3 Fresh Water Pump
9.3.1 Fresh water pump construction
The fresh water pump is of the centrifugal (volute) type, and circulates water from the fresh water tank to
the cylinders and cylinder head.
The fresh water pump consists of the pump body, impeller, pump shaft, bearing unit and mechanical
seal. The V pulley on the end of the pump shaft is driven by a V belt from the crankshaft.
The bearing unit assembled in the pump shaft uses grease lubricated ball bearings and cannot be
disassembled.
The totally enclosed mechanical seal spring presses the impeller seal mounted on the impeller side
away from the pump body side. This prevents water from leaking along the pump shaft.
As the impeller and pulley flanges are press fit assembled, they cannot be disassembled.
Cylinder head
Thermostat
To cylinder block
O-ring
Spacer
Fresh water pump
From heat
exchanger
(fresh water tank)
From oil cooler
To heat exchanger
(fresh water tank)
For water
temperature switch
For sender unit
Spacer
To cylinder body
Gasket
Pump plate
Gasket
Impeller
Bypass port
Pipe flange
O-ring
V-pulley flange
Pump body
Mechanical seal
Thermostat
Bearing unit
V-pulley