2QM20 noise & Vibration

[Don Bodemann]

Just bought a 1977 H-33 (2QM20 20 HP)and took it out for the first time today. Noticed quite a bit of Vibration/noise when motoring and was wondering if this is normal and/or is there some things I can do to improve?Thanks,Don Bodemannsailbode@gis.net

 

[Bob Clark]

Yanmar 2QM20 noise/vibration

Hi Don, You mention a noisy Yanmar 2QM20 in your 1977 Beneteau. I have a 1908 Southern Cross 31 with the same engine, same problem. Last summer I replaced the motor mounts. replaced the prop shaft (which was bent .007") and installed a Prop Saver (a plastic donut in line with the prop shaft). Well, the vibration is reduced somewhat. I am thinking the 2QM20 is just plain noisy. What do you think?Bob Clark

 

[Sam Lust]

If your rig don't shake ---

Your 2QM aint runnin'.The 2GM in my 33 would cause various bits and pieces to shake, rattle and rumble at diferent RPM ranges. My favorite was watching my twin backstays twanging in unison and harmony. I cured the problem by putting in a 3GM30F. Much, much smoother.I know you know about alignment and mount condition so I won't go there. I'd be curious to see if "Bushings Inc." engine mounts would handle the problem better than the Yanmar OE. I have a set you can borrow to try out if you want to take a few hours and drill another 8 holes.

 

[Gordon Torresen]

Q shakers

The Q series Yanmar engines were notorious for their shaking. We tamed a few by making careful adjustment to the injection timing. If the timing is too early, the crankshaft tries to go backwards each time a piston nears the top of a stroke. Retarding the timing to the specs does away with this erratic motion. Its a very critical adjustment and is done by changing the shims under the injection pump. Take out too many and the pump gets damaged in one revolution. It is probably a good job for someone with the right equipment, who has done the job before, who has the patience to get it right and who believes that he can make it better.