Flushing The Cooling System - Mercury 25 Series Owner's Manual

EVERY 300 HOURS OF USE OR THREE YEARS
• Replace water pump impeller (more often if overheating
occurs or reduced water pressure is noted).
BEFORE PERIODS OF STORAGE
• Refer to Storage procedure. See Storage section.

Flushing the Cooling System

FLUSHING
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.
Use a Mercury Precision or Quicksilver Accessory (or equivalent)
flushing attachment.
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. Remove the water plug from the motor and screw in the
associated flushing plug (hose adapter).
MAINTENANCE
WARNING
!
80
1.