Yanmar 4JH4E - Fresh Water Pump Inspection

9. Coolant system
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9.3.4 Fresh water pump inspection
(1) Bearing unit inspection
Rotate the impeller smoothly. If the
rotation is not smooth or abnormal noise
is head due to excessive bearing play or
contact with other parts, replace the
pump as an assembly
(2) Impeller inspection
Check the impeller blade, and replace if
damaged or corroded, or if the impeller
blade is worn due to contact with pump
body.
(3) Check the holes in the fresh water and
bypass lines, clean out any dirt or other
foreign matter and repair as necessary.
(4) Replace the pump as an assembly if
there is excessive water leakage due to
mechanical seal or impeller seal wear or
damage.
(5) Inspect the fresh water pump body and
flange, clean off scale and rust, and
replace if corroded.
(6) Measure the clearance between the
Impeller and the pump body, by pushing
the impeller all the way towards the
body, and inserting a thickness gauge
diagonally between the impeller and the
body.
Measure the clearance between the
impeller and the plate (pump body
bracket) by placing a straight-edge
against the end of the pump body and
inserting a thickness gauge between the
impeller and the straight-edge.