MerCruiser 8.1 MAG, Owner'S Manual

Page: 123 / 152

Section 5 - Maintenance
90-864839070 AUGUST 2007 Page 115
2.
On Bravo closed cooled models using the sterndrive seawater inlet and a
through-hull or through-transom alternative water pickup:
Flushing water will need
to be supplied 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.
If equipped with a seacock, close the seacock in the hose from the alternative
water pickup.
b. If not equipped with a seacock, disconnect the hose from the alternative water
pickup and plug both ends.
c. If there is not a hose running to the transom, refer to
Alternative Water
Pickups
.
3. If flushing the cooling system with the boat in the water:
a. Raise sterndrive to trailer position.
b. Install the appropriate flushing attachment over the water inlet holes in the gear
housing.
c. Lower sterndrive to full down (in) position.
4. If flushing the cooling system with the boat out of the water:
a. Lower sterndrive to full down (in) position.
!
WARNING
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. Remove propeller.
c. Install the appropriate flushing attachment over the water inlet holes in the gear
housing.
5. Connect a hose between the flushing attachment and water source.
6. With the sterndrive in normal operating position, open the water source fully.
7. Place the remote control in the neutral idle speed position and start engine.
NOTICE
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.
8. Depress the throttle‑only button and slowly advance the throttle until the engine
reaches 1300 RPM (± 100 RPM).
9. Observe the water temperature gauge to ensure that the engine is operating in the
normal range.
10. Operate engine with sterndrive in neutral for about 10 minutes or until discharge water
is clear.
11. Slowly return throttle to idle speed position.
12. Stop the engine.
13. Shut off water and remove flushing attachment.
14. Remove the seawater inlet hose from the seawater pump and plug the hose to prevent
water from siphoning into the engine.