450: Lagoon 450 Vibration - normal?

[randomguy1981]

Sitting on a lagoon 450 at the moment and suffering from some vibration when RPM's are above 1600

Seems to be both engines that are doing this

Props are fixed 2 blade

Is this something to expect with the fixed 2 blade?

I am sitting at the salon table and its vibrating slightly to give you some idea of the extent.

[randomguy1981]

Perhaps a rudder alignment issue?

Surely the lower unit of the saildrive can not be out of alignment as its 4 bolts fixed I believe?

[randomguy1981]

After a little more investigation the starboard engine has a large whine coming from it in gear.

This engine recently had its SD shaft replaced due to wear.

[Bean Counter]

I would worry about a large whine. Could be they did not make the correct shim adjustments for the new shaft, or maybe forgot to re-install them altogether, could cause bearing failure. I take it the gear oil level is correct (lower end of the longer dipstick for the SD50). Also you may have heavy fishing line caught around the prop and it has worked its way on to the shaft.

[randomguy1981]

Going to dive down there today and make sure nothing is around the shaft

What is the process for the shim adjustments for the shaft? So when I speak to the mechanic I can see if he is dialled in on this requirement.

Gear oil level - slightly over halfway between markers

Thank you for the response

[Bean Counter]

Shims. adjustments are described in the SD 50 Service manual, your Yanmar mechanic should have this manual. It would be easy enough to get distracted and forget to re-install the shims ( I did and my wife pointed them out to me after I had rebuilt the second drive, they were sitting on an oily rag and forgotten about, so I had to re-install)

[caymancat]

While you are under the boat, check that there is no play in the shaft. Play would create vibration. If there is play, you will also start to see water in the SD oil.