miky2884":2o0tatkc said:
I just dont see why if you have the resource to give the motor a fresh water flush why you wouldn't take advantage of it.
Studies and tests by the military have shown that FW flushing on typical potable water pressures, e.g., your house hose outlet, doesn't do anything. Look up the MST Guardian flushing system that the military installed on all of their service OBs. MST is now apparently out of business, but you can read about their system here (
http://www.merdocmarine-antigua.com/archives/mst.htm), as they used on-board pressure injectors to triple the pressure of the water flushing through the motor.
If one were to flush, I'd say DO NOT run the motor, as MST testing proved that 90% of water pump impeller damage occurs during engine flushing. Again, because there is just simply not enough water pressure available from a city/municipal water system to adequately supply a modern high performance marine waterpump.
IMHO the Yamaha statement to "flush the motor after every use"
only serves to protect Yamaha's interest in case of MORE lawsuits filed in the event that more of their crappy aluminum alloy is used .. and fails, i.e., example their recent failing and corroding exhaust housings.
But as with anything ... your mileage may vary. If you have the time to flush (again, I would NOT run the motor) then sure - have at it! At best, maybe it helps your motor (specially if a Yamaha) and at worst, you only lose 10-15 minutes of your life each time.