[C320-list] Severe vibration at 1000 RPMs after engine mount replacement

[P.F. Ross]

Yep, same here.  Smooth everywhere except below or close to 1000 RPM.
Looks like maybe I need to review my manual for minimum idle settings.

I don't remember this issue when the boat was brand new, but have lived
with it now for well over 20 yrs.  Everytime I think about replacing my
engine mounts, I see a post like yours and move that task down the list.

Sorry not to be of more help.

Frank Ross
Beta Wave #206 (with a Perkins)

On Fri, Dec 11, 2020 at 12:05 PM Art Harden <artstree at aol.com> wrote:

> If can reach it with dish soap, it makes  good lubricant and the just
> washes away.
>
> Art Harden
> Catalina 320 “Tortuga” #243
> 937-477-5544
>
> > On Dec 11, 2020, at 12:56 PM, Paul Borghese <packetpaul at gmail.com>
> wrote:
> >
> > Do you have the idle set to 1100?
> >
> >> On Fri, Dec 11, 2020 at 11:34 AM Age Of Aquariums <
> dan at ageofaquariums.biz>
> >> wrote:
> >>
> >> my perkins does the same thing , i don’t go below 1100
> >>
> >>>> On Dec 11, 2020, at 8:17 AM, Paul Borghese <packetpaul at gmail.com>
> wrote:
> >>>
> >>> A boatyard replaced the engine mounts in my Cat 320 Perkins M30
> engine.
> >> The
> >>> engine is noticeably smoother at all RPMs except one, 1000 RPMs.  At
> >>> exactly 1000 RPMs the harmonic vibration causes the engine to shake
> >>> violently.
> >>>
> >>> The vibration occurs every time on every transmission setting (
> neutral,
> >>> forward, reverse).
> >>>
> >>> Any ideas as to the issue?  I have an uneducated theory. The yard used
> >>> off-brand engine mounts that were not tuned to the engine causing the
> >>> severe vibration.  Or maybe the bolts are not torqued to the correct
> >>> specification.
> >>>
> >>> Thoughts?
> >>>
> >>>
> >>> Paul
> >>
> >>
>
>