Yamaha overheating 225 4 strokes

[BOB CARDINAL]

Hello
i have twin yamaha 225 4 strokes 2002. Over the past couple of years the temp alarms go off periodicaly. I change the water pumps and thermostates every year, but the alarms still sound. When i drop the lower units to change the water pumps is there a way to flush out the motors with the units off? I'm not that familar with yamahas, do they have popit valves like mercurys and would they cause overheating. The alarms sound at high speed, low speed, and in between. What can i do or clean out?
Thanks for your time
bob c

 

[rodbolt]

Re: Yamaha overheating 225 4 strokes

the poppit valve is located on the powerhead adapter,remove the side and rear covers and its the 1 7\16ths hex nut with a 10mm hex lock bolt.
if that wont cure it then its possible the water diverter plate under the powerhead has a hole corroded in it.

 

[sdsaw]

Re: Yamaha overheating 225 4 strokes

if that wont cure it then its possible the water diverter plate under the powerhead has a hole corroded in it.

http://www.thehulltruth.com/boating-forum/234115-yamaha-exhaust-corrosion-4.html