Flushing The Cooling System - Mercury 2.5 FourStroke Operation, Maintenance & Installation Manual

• Check the hydraulic steering fluid level, if equipped
AFTER EACH USE
• Wash the power package exterior with fresh water
• Flush the outboard cooling system, saltwater or brackish water only
ANNUALLY OR 100 HOURS
• Grease the engine, if applicable
• Change the engine oil and filter, if equipped
• Inspect the thermostat, saltwater or brackish water only
• Add Quickleen to the fuel tank, once per year, per engine
• Apply antiseize to the spark plug threads
• Replace the gear lubricant
• Inspect the corrosion control anodes
• Lubricate the propeller shaft splines
• Replace all filters on the suction side of the fuel system—dealer item
• Lubricate the driveshaft splines—dealer item
• Check the tightness on all the fasteners—dealer item
• Check the torque of the outboard mounting hardware—dealer item
• Check the battery condition and tightness of the battery cable connection,
if equipped—dealer item
THREE YEARS OR 300 HOURS
• Replace the spark plugs
• Replace the water pump impeller—dealer item
• Inspect the carbon fiber reeds, if equipped—dealer item
• Inspect the wire harness connectors—dealer item
• 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.
Use a Mercury Precision or Quicksilver accessory (or equivalent) flushing
attachment.
NOTE: Do not run the engine while flushing the cooling system.
1. Remove the plug and gasket.
MAINTENANCE
34
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