Topics

Engine Vibration


Ian Park
 

My Prima M50 is vibrating badly at the rear (end furthest from the C Drive). It’s OK below 1800 rpm.
All the engine And transmission mounts were replaced in Martinique in 2018 and the engine re-aligned.
I am assuming one of the rear mounts has failed. Is there anything else that can cause this vibration?
I had refurbished injectors fitted before setting off at the beginning of August and I have re-bled them to ensure no air locks.
Is my suspicion of a failed engine mount(s) most likely?


Ian Park
 

Sorry, failed to put my name etc.

Ian
’Ocean Hobo’ Santorin 96 currently in the Scilly Isles.


 

The Vetus Coupling may be failing and/or the alignment may have been done incorrectly. Did they use a fixed coupling alignment tool?


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Wed, Aug 26, 2020 at 11:33 AM Ian Park <parkianj@...> wrote:
Sorry, failed to put my name etc.

Ian
’Ocean Hobo’ Santorin 96 currently in the Scilly Isles.


Arno Luijten
 

Is the vibration both present in Neutral and in Gear?

Given the fact they have been working on the injectors it could be one of the cylinders not firing at higher RPMs. Did the phenomenon started out of the blue or after after some work done to the engine/transmission.

Regards,

Arno Luijten
SV Luna,
A54-121


James Alton
 

Ian,

   Lots of possibilities here and the experts on the BB will help.  Just adding that especially since work was done not too long ago to check all of the pertinent fasteners to be sure that nothing has worked itself loose.

Best of luck,

James
SV Sueño
Maramu #220

On Aug 26, 2020, at 12:29 PM, Ian Park <parkianj@...> wrote:

My Prima M50 is vibrating badly at the rear (end furthest from the C Drive). It’s OK below 1800 rpm.
All the engine And transmission mounts were replaced in Martinique in 2018 and the engine re-aligned.
I am assuming one of the rear mounts has failed. Is there anything else that can cause this vibration?
I had refurbished injectors fitted before setting off at the beginning of August and I have re-bled them to ensure no air locks.
Is my suspicion of a failed engine mount(s) most likely?


Craig Briggs
 

Hi Ian,
As Arno, James and Bill point out, there could be several sources but your suspicion does seem likely, notwithstanding new mounts. You can easily check if it is a bad engine mount, though. First, stand on the engine and wiggle around with your full weight. If the engine doesn't remain firmly planted you'll easily spot the failed mount(s). (Mine was really wobbly and it was the starboard rear mount!)  You can also rev up the engine and look for one side or the other to lift up, signaling a failed mount. Do it in forward and reverse to identify the bad mount.

However, it being only at high RPM and with having just installed new mounts, that seems it is something else like the suggestions to check the coupling. On my boat years after the failed mount and on two other SN's I've looked at it was loose bolts on the Vetus coupling, and that was, indeed, more noticeable at higher rpm, although there was a rattle on deacceleration.  Put a wrench on all the bolts and check if they are tight - do the same on the engine mounts while you're at it.

One other procedure I've done after popping my engine up to the cockpit to more easily do various maintenance on it is to put it back in place and just loosely tighten the mounting bolts. Then start it up, run it at low rpm in forward and reverse to let it find it's "sweet spot" and then torque up the bolts. You can do that, of course, without uncoupling it or lifting it out of the engine room. It might just let it "settle in" to where it should be.

Keep us posted - would love to hear the final diagnosis.

Craig - SN68 Sangaris, Tropic Isle Harbor, FL