Seawater Pickup Pump - Mercury MerCruiser MCM 454 Mag MPI Service Manual

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SEAWATER COOLED MODELS

3. Check drain plug and lens cover bolts. Tighten securely. Do not overtighten cover bolts

or cover may warp and leak water into boat.

4. Open seacock, if equipped.

Seawater Pickup Pump

If an overheating problem exists, use this test to determine if a sufficient amount of water

is being supplied to cool the engine.

IMPORTANT: The following information should be observed before proceeding with

BOAT MUST BE IN THE WATER FOR THIS TEST. This test CANNOT BE performed

with a flush-test device and water hose.

The ability of this test to detect a problem is greatly dependent upon the accuracy

with which it is performed. An error in setting the engine RPM, timing the test or

measuring the water output will affect the overall accuracy of the test and may

produce misleading results. To help ensure accurate results, a shop tachometer

with an error of less than 5% should be used. The boat tachometer definitely

should not be used as its accuracy is questionable. A stop watch should be used

to time the duration of the test to help ensure that the accuracy is maintained

within one second. An 8 qt. (7.6 L) or larger capacity container should be used to

measure water output.

Due to the manner in which this test is performed, it may not be possible to detect

a marginal condition or a high-speed water pump output problem.

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Lens Cover Bolts (2, One Hidden In This View)

SERVICE MANUAL NUMBER 23

90-861326--1 MARCH 1999

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