Service Manual

Sea Water System Diagnostics ISB, ISBe and QSB (Common Rail [...]
Page 8-114 Section 8 - Cooling System - Group 08
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Test
Attach a vacuum gauge to the inlet side of the sea water
pump.
Start the engine.
Record the sea water inlet restriction from low idle to rated
speed at 500 rpm increments. This test can be conducted
while the vessel is at the dock and not in gear or
underway.
Refer to Procedure 018-018 for Marine engine
specifications.
If the sea water inlet restriction is above specification, the
source of the restriction must be found. Troubleshooting
and repair of excessive sea water restriction is a boat
manufacturer or boat owner responsibility. Refer to the
vessel's OEM service manual. If the inlet restriction is
within the specification and the complaint can not be
verified at the dock, the test must be repeated underway.
Areas to inspect for restriction are a plugged sea water
strainer, sea water valve not fully open, defective hose
liner in a supply hose, or debris in the inlet hose.