Boat Out Of The Water - MerCruiser 350 MAG Owner's Manual

3. To properly vent the cooling system, remove the blue drain plug from the side of the
thermostat housing within 30 seconds.
4. Remove the two blue drain plugs from the seawater pickup pump (front, starboard side).
5. Verify that water is draining from each opening.
6. Allow the system to drain for a minimum of five minutes. Mercury MerCruiser
recommends leaving the drain system open while transporting the boat or while
performing other maintenance to ensure that all water is drained.
7. Crank the engine over slightly with starter motor to purge any water trapped in the
seawater pickup pump. Do not allow the engine to start.
8. Prior to launching the boat or starting the engine, close the drain system by installing
the four blue drain plugs.
9. Open the seacock, if equipped, or unplug and reconnect the water inlet hose prior to
operating the engine.

BOAT OUT OF THE WATER

NOTE: Use this procedure if your engine is not equipped with an air actuated single point
drain system or if the single point drain system fails.
1. Place the boat on a level surface to ensure complete draining of the system.
90-864195072 OCTOBER 2007
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a - Blue drain plug location
a - Blue drain plugs
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Section 6 - Storage
Page 115