Legend 37.5 Prop Issues

[TKMLSMMC]

My Engine, Coupling, Shaft And Cutlass Bearing Are In Good Shape But I Am Still Getting Vibrations When Motoring And Can't Get The Rpm's Above 3000. I Switched From A 17/14 Three Bland To A Michigan 17/13 Three Blade The Rpms Shot Up But The Vibration Got Worse. I Am Thinking About Putting The Old Prop Back On And Am Wondeering If This Version Of Hunter's Just Vibrate. Any Thoughts.

Thanks

Tom

 

[Ron McCoy]

I suspect not all is as good as you might think - given that you still have vibratiions. Something is causing it. Now for the detective work. Have you had your prop (s) balanced? Even brand new, never been used props can be out of balance. You need to have this checked by a reputable prop shop. While you're at it, thoroughly check the cutlass bearing for any movement. There shouldn't be any - snug, but not tight. Next, check your engine mounts. You should be able to put a credit card inside the mounts while the engine is running. Check all four - are any bottoming out? I'd also check the position of the shaft as it exits the stuffing box - is it centered inside the fitting? Unfortunately, checking the cutlass and stuffing box will have to be done while the boat is hauled. The prop can be removed/reinstalled by qualified divers. Good luck.

 

[george schmidbauer]

Did you check engine aliment?

 

[Steve Dion]

Tom: How do you know that all of these items are okay? Have you removed the shaft and had it checked? Motor mounts on Yanmars are critical (regardless of some may tell you). The motor mounts for many of the Yanmars are NOT the same on all four corners.

I would suggest that you take the props to a good shop and have them check them for balance (no guarantees). Have the shaft and motor mounts checked. I suggest that you get a "Yanmar" certified mechanic to help with this check out.

Too many times there are these technicians that "think" that they know what they are doing (but they really don't).

PS: What engine do you have?