1999 200HP Yamaha???????????

[CaptJ]

Originally Posted by RABBITFISH

When my 2001 Yamaha OX66 225 hp started to run hot while flushing, I learned many things............the thermostats were sticking slightly, and the PRV valve was a little dirty....I replaced the thermostats, cleaning the area as well as possible, removed and cleaned the PRV also......after doing these maintenence items..the water pressure guage showed 15 to 20 psi and no longer had a problem with overheating while flushing.....the telltale stream also improved. The water pump can send the water pressure up to the top of the motor only when the PRV is closed....... if it's open only slightly, it lowers the pressure and the water flow won't reach the top of the motor causing it to overheat at idle....When running at a higher rpm in the water, the PRV will open and release any overpressure........

Guess changing tstats and prv will be the next step. But my main issue is that it has been doing this since day one NEW. Could be worse though, at least I am still on the water and motor runs great.

I appreciate all the input you guys are always willing to give. Just a puzzle I want to solve.