Mercury 350 MAG Manual page 147

7. Immediately remove the blue drain plug from the side of the thermostat housing or the heat exchanger. This must be removed
within 30 seconds to properly vent the cooling system.
a
b
Closed Cooled Models
a - Blue drain plug location
b - Blue air pump
c - Air manifold
d - Green indicators
8. Verify that water is draining from each opening. If not, use the Three Point Manual Drain System instructions.
a
9. Allow the system to drain for a minimum of five minutes. Pump air as necessary to keep the green indicators extended.
10. Crank the engine over slightly with the starter motor to purge any water trapped in the seawater pump. Do not allow engine
to start.
11. Reinstall the blue drain plug in the thermostat housing or heat exchanger.
12. Remove the air pump from the air manifold and return it to the mounting bracket.
13. Mercury MerCruiser recommends leaving the drain system open while transporting the boat or while performing other
maintenance. This helps ensure that all water is drained.
90-8M0050539 MAY 2011
eng
c
d
b
a
6124
Seawater Cooled Models
a -
b -
6133
Section 6 - Storage
c
6125
Port side drain location
Starboard side drain location
b
d
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