Alternative Water Pickups - MerCruiser 4.3L TKS Sterndrive Owner's Manual

Section 5 - Maintenance
Flushing the engine with the boat in the water can cause seawater to flow into the engine, resulting in engine damage. Close
the seacock before flushing the engine. Keep the seacock closed until starting the engine.
1. On seawater cooled models: Proceed to Step 5. or Step 6.
NOTE: Closed cooled models are equipped with a heat exchanger on the front of the engine.
2. On Alpha closed cooled models with the sterndrive seawater inlet blocked: Flushing water will need to be supplied to
the sterndrive unit and to the engine. Refer to Alternative Water Pickups.
3.
On Bravo closed cooled models using the sterndrive seawater inlet and a through the hull or through the transom
alternative water pickup: Flushing water will need to be supplied to only the sterndrive unit 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.
4. If flushing the cooling system with the boat in the water:
a. Raise sterndrive unit to trailer position.
b. Install the appropriate flushing attachment over the water inlet holes in the gear housing.
c. Lower sterndrive unit to full down/in position.
5. If flushing the cooling system with the boat out of the water:
a. Lower sterndrive unit to full down/in position.
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.
6. Connect hose between flushing attachment and water source.
7. With sterndrive unit 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.
16. Tag the ignition switch with an appropriate tag requiring the seawater inlet hose to be reconnected prior to operating engine.

Alternative Water Pickups

IMPORTANT: Two water sources are needed for this procedure.
NOTE: Flushing is needed only for salty, brackish, mineral laden or polluted water applications. Flushing is recommended after
each outing for best results.
IMPORTANT: Engines with the sterndrive water inlet blocked off at the gimbal housing and using a through the hull water inlet
need a supply of cooling water available to both the sterndrive unit and to the engine during operation.
1. If flushing the cooling system with the boat in the water:
a. Raise sterndrive unit to trailer position.
b. Install the appropriate flushing attachment over the water inlet holes in the gear housing.
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NOTICE
WARNING
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NOTICE
90-8M0053265 NOVEMBER 2010