Service Manual

Sea Water System Diagnostics ISB, ISBe and QSB (Common Rail [...]
Page 8-116 Section 8 - Cooling System - Group 08
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If sea water pressure is not present, check the pump for
damage. Refer to Procedure 008-057
If the sea water pump outlet pressure is above the
maximum specification test the individual sea water
system components for excessive pressure drop as
described in the Pressure Differential Test step.
Refer to Procedure 018-018 for Marine engine
specifications.
Pressure Differential Test
Check the sea water pressure at the inlet side of the
aftercooler at the rated rpm. Record the reading. If the
pressure drop between the sea water pump outlet and the
aftercooler inlet exceeds the maximum specification,
check or replace the fuel cooler.
Refer to Procedure 018-018 for Marine engine
specifications.
If the pressure drop is within specification, check the sea
water pressure at the discharge side of the aftercooler
outlet. Record the reading.
If the pressure drop between the inlet side of the
aftercooler exceeds the maximum, check for blockage in
the lower cap area of the aftercooler. Clean or replace if
necessary. Refer to Procedure 010-005
Shut off the sea water supply valve and remove the lower
aftercooler sea water supply hose. Clean the debris from
the aftercooler and cap. Remove the upper sea water
hose and back flush the system.
Refer to Procedure 018-018 for Marine engine
specifications.