3.7 Mercruiser vibration

[steve931]

I just completed a longblock over-haul on a 3.7 Mercruiser and it has a slight vibration at certain rpm's. I was not sure about the rear motor mounts, are there any washers or spring shims that go inbetween the rear motor mount and the boat rear motor mount.

 

[Bt Doctur]

Re: 3.7 Mercruiser vibration

there are a few parts that reside at the rear mount. you should have seen them when you removed the motor.you did pull the drive first?? Vibration may be engine misalignment and is ripping up the coupler.

 

[Don S]

Re: 3.7 Mercruiser vibration

Not only are there washers (Metal and fiber) ans spacers, you also MUST get the alignment just right or you will be pulling the engine and replacing that $300+ coupler because the splines are gone.
I also hope when you did the overhaul, that you used the alignment tool to align the oil pump. Otherwise you WILL loose the rod operating the oil pump.