High Pitched Noise At Certain RPMS

[Jim]

I just bought a 2002 Hunter 306 with a 18 hp Yanmar, It has a high pitched noise between 1500 and 2000 RPMs. Hunter replaced the prop and the noise stopped for about 1 hour of motoring , then returned. In neutral there is no noise and she purrs like a kitten through all RPMs. The Dealer although knowledgeable seems not to know what to do next. Thanks for any help.

 

[Ed Allen]

BELTS?

Check the belts to be sure they are not loose. it they are tighen them a bit. If not get a piece of dowel or broom stick and make a listening device. put on end on the engine and one end on the flap of the ear and listen. move it arround tillyou find out where its coming from. try the water pumps and generator ect. maybe you can find it yourself.

 

[Jim]

stuffing box

check your stuffing box packing nut or dripless seal, see if the noise is coming from there. packing could be too tight or if a dripless seal may need to wear in.