With The Boat In The Water - Mercury 4.2 Diesel Operation & Maintenance Manual

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.
6. Operate the engine at idle speed in neutral for about 10 minutes, or until the discharge water is clear.
7. Observe the water temperature gauge to ensure that the engine is operating in the normal range.
8. Stop the engine.
9. Shut off the water tap.
10. Remove the adapter from the seawater pump inlet hose connection.
11. Reconnect the seawater inlet hose. Tighten the hose clamps securely.

With the Boat in the Water

Without sufficient cooling water, the engine, the water pump, and other components will overheat and suffer damage. Provide
a sufficient supply of water to the water inlets during operation.
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. Close the seacock (if equipped) or disconnect and plug the seawater inlet hose.
a
a - Seacock
b - Seawater inlet hose
c - Plug
2. Using an suitable adapter, connect a flushing hose from a water tap to the seawater inlet hose connected to the seawater
pump inlet.
3. Partially open the water source to about 1/2 maximum. Do not use full water pressure.
4. Place the remote control in the neutral, idle speed position and start the engine.
90-8M0113988 DECEMBER 2015
eng
NOTICE
NOTICE
NOTICE
c
a -
b -
d
c -
d -
a
b
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Section 4 - Maintenance
b
c
13171
2.8 shown, 4.2 similar
Adapter
Flushing hose
Water tap
Seawater inlet hose
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