I have a Yanmar
3GM30F in a 1999 Beneteau Oceanis
352. The engine
is original to the boat and has 347 hrs. I motor
at 2500- 2800 rpms and at anchor
I no load idle at 1500 rpm
to heat shower water
and or charge batteries.
Yesterday I was motoring @ 2500 rpm
when the engine
started making a knocking sound similar to the sound of a rod knocking. A large cloud of white smoke was belching from the exhaust
. I lowered the rpms to 1800 rpm's the rattling and smoke stopped. I eased the trottle back up to 2500 after a few moments the rattling and white smoke started again.
Today at the dock
I no load trottled up to 3600 rpm. After about a minute the knocking started as well as a thick production of white smoke. Again I lowered the trottle to 1800 rpm and the symptons stopped. There was an oily film on the water
Idling and at low loaded and no load rpm's the engine sounds perfect.
Does anyone have any ideas or advice?
Thank you, in advance for your help.