YAMAHA fresh water flush

pine island fred

Lieutenant Junior Grade
Joined
Dec 20, 2002
Messages
1,144
Good timing, saw a few recent post. Yesterday just finished servicing my F-115 while it was out of the water. Dealer replaced my thermostat for $47 so I figured I would pull the housing and see what it looked like. What a surprise!!
Bought the engine and felt real good that I would not fall in the water trying to put the muffs on to flush the unit after each use. Been a religion to me to flush. Do it all the time, inspite of the mosquitoes and no-see-ems. So I run the hose and water comes out of everywhere out the leg. Anyway, I remove the thermostat and look down the cooling passages. Looks like I was wasting my time! Quite a bit of buildup. Why? Yamaha mtc. manual says do not run the engine, just plug in the hose and flush for 15 mins. Unless I am missing something you are not really flushing the block, water will never circulate past the thermostat, just fill till the air press. and water press. are equal in the block and just sit there. Maby I am missing something, but that the way I see it.
Me being me I have looked for a way around this design problem. Over the years I have installed a few auto thermostats and have run across a few that have had a small V cut into the disk to allow a bit of water flow past the stat when it was closed. I figure a hole no more than 1/4 in. drilled in the stat disk will allow water to fully circulate past the stat and really flush my 10k investment. Down side would be a longer time for the engine to heat up but the water temp. here never goes lower than 70F. ( eat your hearts out)
Neighbor has an older RUDE with an attachment that according to his manual, he can run the motor while he is flushing. He has not torn up an impellors yet but I am reluctant to try it on my YAHAHA as a new pump assy. is $97. Would welcome your comments or insite regards FRED
 
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