Flushing The Cooling System - Mercury 40 CT Maintenance And Installation Manual

• Check the remote control cable adjustment, if equipped—dealer item
• Replace the high‑pressure fuel filter, if equipped—dealer item
• Replace the accessory drive belt, if equipped—dealer item
• Check the power trim fluid level, if equipped—dealer item
• Inspect the engine motor mounts—dealer item

Flushing the Cooling System

Flush the internal water passages of the outboard with fresh water after each
use in salt, polluted, or muddy water. This will help prevent a buildup of
deposits from clogging the internal water passages.
IMPORTANT: The engine must be run during flushing in order to open the
thermostat and circulate water through the water passages.
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.
1. Place the outboard in either the operating position (vertical) or in a tilted
position.
2. Remove the propeller. Refer to Propeller Replacement.
3. Thread a water hose into the rear fitting. Partially open the water tap (1/2
maximum). Do not open the water tap all the way as this allows a high
pressure flow of water.
IMPORTANT: Do not run engine above idle when flushing.
4. Shift the outboard into neutral. Start the engine and flush the cooling
system for at least five minutes. Keep the engine speed at idle.
5. Stop the engine. Turn off the water and remove the hose. Reinstall the
propeller.
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MAINTENANCE
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