Always great information from this group and I’m hoping someone can suggest a solution to my latest problem. When I exceed 2200 rpm there is a definite vibration that increases as I increase throttle. However, if I’m in reverse (or neutral) I can go full throttle and with no vibration. Transmission was replaced 2 years ago with a new shaft and cutlass bearing, and this problem surfaced a few months after this work. I had the engine alignment checked and it was fine. Now the boat is out of the water I’m wondering what I can do to troubleshoot this annoying vibration?
New shaft, new cutlass bearing and a realigned engine. My next step would be to check the prop. Have it rebalanced. Low cost and should have been done as part of the rebuild.
If that does not cure it and if the vibration was not evident immediately after rebuild that implies something is now out of alignment and has degraded the support / alignment over time. Unfortunately that means you need to start back at then engine and check all the elements from engine alignment, strut support, cutlass bearing wear, shaft trueness and prop mounting.
Hi Graham, when fitting up the new prop shaft is it possible that the prop is now closer to the hull? If so the turbulence off the prop tips against the hull could be the source of your vibration.
Thank you for the great suggestions. I checked what I could this weekend and it all seems normal. The problem is now in the hands of a mechanic. He thought the strut holding the cutlass bearing might be out of line, also going to check shaft coupling.