Flushing The Cooling System (Lower Unit) - Mercury 250 XS OptiMax Operation, Maintenance & Installation Manual

Flushing the Cooling System (Lower Unit)

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.
a - Fleet Master gearcase
b - Sport Master gearcase
c - Water hose
d - Flushing attachments
1. Remove the propeller. Refer to Replacing the Propeller.
2. Fleet Master gearcases – Install the appropriate flushing attachment so
the rubber cups fit tightly over the strut intake holes. Attach the Dual
Water Flush Seal over the nose inlets.
3. Sport Master gearcases – Install the appropriate flushing attachment so
the nose cone cup fits tightly over the intake holes.
4. Attach a water hose to the flushing attachment. Turn on the water and
adjust the flow so water is leaking around the rubber cups or nose cone
cup to ensure the engine receives an adequate supply of cooling water.
5. Start the engine and run it at idle speed in neutral shift position.
6. Adjust water flow so excess water continues leaking out from around the
rubber cups or nose cone cup to ensure the engine is receiving an
adequate supply of cooling water.
7. Check for water coming out of the water pump indicator hole. Continue
flushing for three to five minutes, carefully monitoring water supply at all
times.
8. Stop the engine, turn off the water, and remove the flushing attachment.
Install the propeller.
eng
MAINTENANCE
WARNING
!
51