1250 rpm noise

[Blue Meanie]

I have a high pitch howling noise(not that loud) from 1250 to 1350 rpm. Hard to tell exactly where is coming from. Started after boat sat on trailer for 5 or 6 weeks. Thought it was maybe dried out shaft packing but took that out and it’s fine with lots of wax left in the packing. Made sure I had a drip for lubrication. Seems like if you jump to 1250-1300 rpm it doesn’t appear until the boat gets up to speed for that RPM then comes the howl. Thought maybe turbo charger but overall engine runs well no excess smoke or any other symptoms at high or low RPM. Thanks in advance for any ideas.

 

[KennyMarrs]

This sounds like the turbo starting to kick in. You can verify this by watching the boost pressure. Once you hear the noise see if the boost pressure PSI is above 0.

-Kenny

 

[TexasEye]

Had a RPM sensitive noise...it was an anchor in the starboard cockpit locker...not always the engine...probably is, but not always...

 

[Blue Meanie]

Thanks for the reply’s
Had to drop the ball for a while with winter etc.
Still have the noise. Pulled the prop and had it serviced over the winter. Went out for a seatrial this Sunday and the howl persists. I feel like if this was the turbo making noise I would lose power or have exhaust smoke issues it don’t. While the noise is going I lift out the wash bin under back seat. The howl seems very prevalent under there. Tried the screwdriver to the earmuff trick and had a listen to gearbox, doesn’t seem like the source and no excessive heat? Tag the screwdriver down near the shaft and again seems like it’s coming from that area for sure. Water lubricated shaft bearing which drools plenty of water in the driveway on trailer seems unlikely ? Anyone experience issue with the shaft bearing making noise?