Vibration

[manuevers]

I have a 1986 Hunter 34 with a Yanmar 3GM30F. The engine vibrates what seems to be a normal amount. However, at certain RPMs, the vibration really seems to resonate on the aft part of boat a make a fair amount of noise. The noise is clearly not from the engine itself.

The best I can figure, the noise is coming from the muffler vibrating against the bulkhead at the hole in the bulkhead that the exhaust passes through.

Anyone have this problem before? Any thoughts how to fix it?

 

[Ed A]

I would bet on engine alignment or a bent shaft or prop/

often is the engine is slightly out of line vibrations happen. when the right rpm is reached it will quit.

can you make it vibrate when it is neutral. that should narrow it down. If its the engine or exaust etc. if would do it with the boat stopped and out of gear as well as when running.

 

[manuevers]

Yes, it also happens in nuetral.

 

[Bill1565]

Our boat vibrated continuously at all rpm, in gear and out when we bought it. You could stop the metalic rattling by reaching under the boat with a boat hook and pulling sideways on the shaft. I replaced the shaft and the worn martec folding prop, moved the strut, and alligned the strut to the shaft log with a laser, then aligned the coupling. Still vibrates at 22-2400 on the tach.

My next step is to replace the shaft log with larger and get rid of the dripless seal, go back to a packing gland in hopes that it restrains the shaft some. Until next haul out, I just avoid the 22-2400 range, either run at 2000 or over 2500.

 

[dakno]

have u checked ur motor mounts

 

[Bill1565]

Twice, once when alligning the motor to the shaft. Once later.