Engine overheat at low RPM

[patricko]

My 2003 Yamaha 225 ox66 overheats only when running at low rpm such as *****ing or when idleing for 5-10 min. I have had the impellor replaced, have purchased but not installed thermostats. What is the best way to proceed?

[boats.net]

Water pump housing may have damage, might have to replace complete water pump.

[99yam40]

My 2003 Yamaha 225 ox66 overheats only when running at low rpm such as *****ing or when idleing for 5-10 min. I have had the impellor replaced, have purchased but not installed thermostats. What is the best way to proceed?

Might have a look/replace PRV to see if it is stucking open and dumping water at low RPMs while installing the stats