MerCruiser 350 MAG Owner's Manual page 104

Section 5 - Maintenance
3. On models using the sterndrive seawater inlet and a through‑hull or through‑transom
alternative water pickup, supply water to only the sterndrive by taking the following
steps to block, or disconnect and block, the hose from the alternative seawater pickup
pump inlet Y‑fitting.
a.
b.
c.
4. If flushing the cooling system with the boat in the water:
a.
b.
c.
5. If flushing the cooling system with the boat out of the water:
a.
Rotating propellers can cause serious injury or death. Never operate the boat out of the
water with a propeller installed. Before installing or removing a propeller, place the drive
unit in neutral and engage the lanyard stop switch to prevent the engine from starting.
Place a block of wood between the propeller blade and the anti‑ventilation plate.
b.
c.
6. Connect hose between flushing attachment and water source.
7. With sterndrive in normal operating position, open the water source fully.
8. Place the remote control in the neutral idle speed position and start engine.
Operating the engine out of the water at high speeds creates suction, which can collapse
the water supply hose and overheat the engine. Do not operate the engine above 1400
RPM out of the water and without sufficient cooling water supply.
9. Depress the throttle‑only button and slowly advance the throttle until the engine
reaches 1300 RPM (± 100 RPM).
10. Observe the water temperature gauge to ensure that the engine is operating in the
normal range.
11. Operate engine with sterndrive in neutral for about 10 minutes or until discharge water
is clear.
12. Slowly return throttle to idle speed position.
13. Stop engine.
14. Shut off water and remove flushing attachment.
15. Remove the seawater inlet hose from the seawater pump and plug the hose to prevent
water from siphoning into the engine.
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If equipped with a seacock, close the seacock in the hose from the alternative
water pickup.
If not equipped with a seacock, disconnect the hose from the alternative water
pickup and plug both ends.
If there is not a hose running to the transom, refer to Alternative Water
Pickups.
Raise sterndrive to trailer position.
Install the appropriate flushing attachment over the water inlet holes in the gear
housing.
Lower sterndrive to full down (in) position.
Lower sterndrive to full down (in) position.
Remove propeller.
Install the appropriate flushing attachment over the water inlet holes in the gear
housing.
WARNING
!
NOTICE
90-864195072 OCTOBER 2007