Engine mounts?

[38mess]

My Perkins M30 had new mounts last year, 45 shore front and back, I always thought they were a little soft as the engine vibration a little on start and stop.
Just in the last few days on start up the engine violently shakes side to side once and then it's smooth, it still shakes the same on shut down.
Could a mount be u/s?
I think I need 55 shore on the rear
Any ideas?

 

[vyv_cox]

Check very carefully that there are no cracks in the metal parts, no delamination of the rubber from steel and that all bolts are tight.

 

[Boater Sam]

My Perkins M30 had new mounts last year, 45 shore front and back, I always thought they were a little soft as the engine vibration a little on start and stop.
Just in the last few days on start up the engine violently shakes side to side once and then it's smooth, it still shakes the same on shut down.
Could a mount be u/s?
I think I need 55 shore on the rear
Any ideas?

Check that you have approximately the same weight on each mount and that you have not got a diagonal pair taking most of the weight. Are all the lower adjuster bolts fully tight? Do not try tightening the upper locknuts. you will lose alignement.

 

[DownWest]

Swapping out two Yanmar engines, a 1GM for a 1GM10 and a a 2GM20 for a Beta.16. Both the originals had the high Yanmar mounts, the replacements lower ones. Not wanting to have overly long bolts from the mountings to the engine, which looked like a recipie for vibration/wobble, I made up some spacers in galv tube to put under the mountings. That got the mounts closer to the engine feet and avoided the problem. Both worked fine.
One does need to be carefull about evening out the loads on the mountings.