temp alarm coming on

[shlacks]

hey guys
i have a yamaha 200hpdi 2001 model Z200TXRA
have had this boat just over a year and it has been used a fair bit with only a problem fowling up every now and then but have just let it sit for 10 mins stopped and go again and it wont bother me again for the day out.. anyway on to more pressing problems i have just taken it out on the water cruiser a river at about 6 knot speed limit for 30 mins and got to open water and opened her up and within about 30 seconds got a constant alarm and noticed the water temp symbol on the tacho gauge was flashing i shut her down straight away checked i hadnt picked up rubbish on the intake and was ok let her cool and was fine run again low speed fine open it up and overheat..... let it cool and then tried just cruising mid speeds 25knots and everything went fine while cruising water pump pressure gauge was ok too. has anyone got any ideas?

and while your at it any ideas with the fowling up problems happens after cruising for a while then go to open it up sometimes only a short period but mostly long cruising.... too much oil being injected???

thanks
matt

 

[99yam40]

have you replaced the stats and water pump as regular maint? Check PRV also while you are at it.
check oil linkage to make sure it is still attached

 

[tommarvin]

I second that, put the stat in a pan of cold water,heat it up slowly what temp does it open. Change water pump/rubber impeller, every year.

We put our overheat sensor in cold water and heat it up slow every year to check, what temp does your overheat buzzer sound?

My gut says its a bad sensor.