Originally Posted by bubb2
I have the same Yanmar in my Beneteau. I put about 50 hrs on the engine per season. The engine has about 300 hrs total on her as I write this post. During the third season the engine started to vibrate at idle so bad it would shake the whole rig. Sounded something awful. After she gained some rpm’s she would smooth out. This puzzled me for some time. What I found was that my throttle cable had stretched and had dropped the idle speed down. Causing the engine to drop a cylinder (firing on only one.) After readjusting the cable (on the left side on the engine as you are facing it) to bring the idle speed back up, no more shaking. Let me know if it works for you
I will second that.
Sometimes it's not even necessary to adjust the cable itself. There is a detente where the cable attaches to the throttle assembly that can be adjusted easily by turning one (maybe two?) nuts. Adjust it a bit and the cable will not be able to pull the throttle assembly back as far, and the idle rpm will stay higher. It will only take about 30 seconds to make the adjustment.
P.S. Welcome to SailNet!