[C320-list] Grinding noise while motor sailing?

[Jon Vez]

Do you have a shaft seal? If so,probably where the noise came from. If not, I would agree that cavitation is a good possibility.

Sent from my iPad

> On Sep 6, 2015, at 9:34 PM, JZ <jeffzinselmeyer at hotmail.com> wrote:
> 
> Hello all, Yesterday i was motor sailing with just my headsail up. I was doing about 7.5knots, engine at my usual cruise rpm of about 2800, all of a sudden there was a grinding/rattling type noise and a slight vibration. I immediately slowed the engine to idle and put it in neutral, the noise stopped as i slowed the engine. I then put it back in forward, no problem, gradually increased rpms to 2800 again, and no problem.  I am baffled as to what it might have been? It was fairly rough out, 4-5ft sea’s, we were battling a head current trying to get to our intended destination, hence the motor sailing. We were heeled over approx 15deg. Once we were anchored, i went below and checked the engine/trans area, everything was tight and secure. I checked all the fluids, normal. Trans oil was bang on and nice and clean.
> 
> Anyone ever run into anything like this?
> 
> It is the Yanmar 3gm30f with the Kanzaki trans, approx 2500 hours.
> 
> Thanks!
> 
> Jeff Zinselmeyer
> s/v Escape #934