Bad Engine Vibration

[Andy]

I recently had my cutlass bering replaced. The boat seems to have a bad viration when in gear. Mechanic thinks it may be the motor mounts need replacing. I think it may not be aligned correctly. What do I need to look at to tell if it's aligned correctly. It is smooth when in neutral. Thanks - Andy

 

[Mike]

Vib

Andy,To do a very quick check if there is such a thing... Break the drive coupling apart, use feeler gage to measure between the mating faces of the driven and driver side of the coupling...it should not be more than .003 of an inch at all points.Take this measurement several times rotating the shaft 1/4 turneach time. This measurement must be taken with the bolts out. You can use a straight edge to check vertical and horizontal alignment..this should be almost dead on. lay the straight edge on top of the flanges and check the sides...the reason for this is the gap(max .003) can be ok but the engine could be off to the left or right or could be high or low in relation to the shaft.. I tried to say this so you understand what I'm talkin about...the other way is to find a millwright with a set of dial indicators. Hopes this helpsMike WD9EOUC-38 s/v Chute the Breeze

 

[Claude McKernan]

Bad Vibes

Shaft could be bent. Watch it while it's turning. You may be able to see a wobble. Prop could be bent. Either you go in, or the boat comes out, and you look at it. Engine/shaft out of alignment; covered by vib. Engine mounts could well be part of the problem. Strut could be loose or bent causing misalignment between the stern tube and cutlass bearing. Possibly a combination of the above. If only life were simple.