Optimax Pro XS 150 continuous tone and white smoke

[Toadee]

Took my boat out for the first time in almost a year. Started first time and ran smooth. After a 10 minute run at 80% throttle I spent about 5 minutes idling into a backwater when I suddenly heard a long continuous tone. I dropped completely off the throttle and the tone stopped. I noticed that the motor was smoking (white) quite noticeably.

The beep occurred a total of three times over the weekend, all at no-wake speeds. At startup the motor doesn't smoke badly, only after a run.

The prop has a darker buildup than I seem to remember.

The water outlet is shower warm after a run.

I managed some WOT runs with no problems. Smooth and responsive.

Any ideas?

[EuropeanAM]

Please see the Forum Announcements, and provide the REQUIRED info when posting. Thanks!

May be as simple as being due for a water pump... but the only way to know for certain is to follow the advice in the below link:

WARNING HORN "BEEPED"

[Toadee]

Turns out it was the water pump impeller that had lost its hysteresis i.e. the fins weren't straightening. The result was a loss of water pressure at idle. The white smoke was steam. Engine is fine!