I bought a 2010 35hp mudbuddy LT. It only has 5 hrs on it and it just started making a horrible vibration noise just above idle, but roll on the throttle and it goes away. I does it less in the water but it is still very annoying. At first I thought it was the muffler shroud or broken baffles inside the muffler, but while throttling up with your hand on the outdrive frame you can feel the vibration. I have not hit anything hard, matter of fact, I have babied it . Could it be a bent shaft or prop. Kinda worried.

im no pro someone else prob. has a better idea but id say bent shaft

My 13 hp does that, its got a hard lope at low idle. Proboly just the motor vibrating before it gets smoothed out.

If it was a bent shaft you couldn't hold onto it at WFO

It's cause it's a Buttbuddy I mean mudbuddy!!!

Ujoint got any play in it??

Check the prop make sure its good and tight just worked on a MBLT 27 that the prop was vibrating and low RPMS the bore and threads are slightly over sized causing the prop to wobble

Took the prop off and ran the motor without the prop and the vibration is gone. Must be the prop. This prop has only 5hrs and no visible damage to the prop. It was hell to get off and impossible to get back on. Had to order a tap to clean the prop hub threads, and ordered a dye to clean up the shaft threads so I can get the prop back on. Taking prop to prop place tomorrow to have it checked for balance. What a pain in the ass.

When you put it back on make sure to use some anti-seize on the threads, will help greatly next time you take it off. Also the vibration could have been because your prop was rusted on. They are supposed to float a little (very little).

bpgast, You may have hit the nail on the head. You said the prop is supposed to float a little. I noticed the other day I could move the prop back and forth barely and I tightened it. Maybe that was when it started vibrating---It makes since. Will back off on the prop nut a little and try it tomorrow.

It could be a number of things

Does the vibration noise sound like a grinding? Almost sounds like a bearing is grinding somewhere at the yoke or in the engine.

Check the set screws on the U joint. If they move, tighten them down and see if that quiets it. If that does it, back em out and loctite em down. If they have a hole in the head of the set screw for safety wire to run through add that too.

bpgast, You were right. I had the prop nut to tight not allowing the prop to float. There is no rubber dampner like on outboard props. That floating play is what absorbs the vibration. Live and learn. Thanks bygast---you de man

Happened to me once. Glad it helped!