When we shifted into reverse our 5 year old Vetus engine made a knocking noise and the boat began vibrating. Any ideas about what might be causing this?
Vetus engine on 33' cherubini
- Thread starter Vtotten
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No, but upon further observation, we discovered that when the engine is in idle, there is vibration of the engine.
Speaking generalities, but "usually" this is caused by a bad engine mount (probably not your case because it is too new), or the prop shaft hitting the inside of the shaft log. It would be good to have the alignment checked to eliminate both of these.. Another one is something hard hitting the hull when in gear.. like a muffler or an exhaust elbow ..
Kloudie: I am not too sure that this is the case. When Yanmar built the GM models they had different mounts for different positions on the engine. I believe that they used different one fore/aft. Other models used different mounts port/starboard so that may be something to check out.
This may be especially true if they are not OEM mounts. I realize that this is NOT a Yanmar, but it could be something similar.
http://www.foreandaftmarine.com/VTMTORMOUNTS.htm
Thanks for all of the suggestions. Upon further inspection, I have discovered that there appears to be a slight misalignment of the drive shaft and engine, which I am thinkng may be caused by a missing bolt in the coupler plate (I am not sure that is what it is called). It had only one, which seemed very surprising. Though I couldn't find a missing bolt, I did find a washer laying below that area.
Vtotten:
Glad that you have discovered the possible (probable) cause of the sudden vibration. Something coming loose at the engine/transmission-to-shaft coupling did flash through my mind when you first posted -- particularly since you had an after-market re-powering not too long ago. But prior to your more detailed look-see, there were just too many possible causes to conjecture about. It's possible that your installer might not have torqued the coupling bolts well enough. Or in any case many new installs require inspections and re-torque of various fasteners (like engine head bolts, car wheels and suspension items, etc) that might get loose after the initial "break-in" period of service. If your new engine came with a manual, you might check what other special "new engine" service items there were. And if not done, follow-up? On the positive side about your coupling, the engine shaft interface is notorious as a site for ugly rusting. Not your case. I've seen pictures of older boats where there is no way the coupling bolts can come loose -- rusted in place instead!
Glad that you have discovered the possible (probable) cause of the sudden vibration. Something coming loose at the engine/transmission-to-shaft coupling did flash through my mind when you first posted -- particularly since you had an after-market re-powering not too long ago. But prior to your more detailed look-see, there were just too many possible causes to conjecture about. It's possible that your installer might not have torqued the coupling bolts well enough. Or in any case many new installs require inspections and re-torque of various fasteners (like engine head bolts, car wheels and suspension items, etc) that might get loose after the initial "break-in" period of service. If your new engine came with a manual, you might check what other special "new engine" service items there were. And if not done, follow-up? On the positive side about your coupling, the engine shaft interface is notorious as a site for ugly rusting. Not your case. I've seen pictures of older boats where there is no way the coupling bolts can come loose -- rusted in place instead!
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