OM-C3 11/21
51
Service and Maintenance - 2000 Hour
SP 27. Inspect and Repair Sea Water Pump
(M50C13, M65C13, M99C13)
• Inspect pump housing for seal leakage
1. Inspect the sea water pump housing weep hole, if
equipped, for evidence of water or oil indicating seal
leakage. If water leakage is evident, replace impeller
and front housing/shaft seal.
If oil leakage is evident, consult an authorized Northern
Lights dealer for repair.
Remove and Inspect Impeller
1. Close sea cock and drain sea water system if not
previously done.
2. Remove six cover plate cap screws with washers and
remove cover plate (A) with O-ring. Remove impeller
end cap from end of impeller bore.
NOTE: Normally the impeller can 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.
3. Carefully remove impeller with cam plate. Be careful
not to damage impeller if in reusable condition.
Remove key from shaft keyway.
The impeller must be installed in the same direction as
removed. Mark the impeller to ensure installation in
proper direction of rotation if impeller is reused.
4. 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.
IMPORTANT: If impeller has chunks of material missing,
the heat exchanger, marine gear oil cooler and any other
circuit that are cooled by raw water should be thoroughly
cleaned and flushed.
Remove cover plate. Cover plate (A), Cam screw (B)
Inspect sea water pump impeller
5. Remove cam screw (B) holding cam plate to impeller
housing bore.
6. Thoroughly clean impeller housing bore and cam plate
(if cam plate is reused.)
