Engine Mount Orientation

[Amp1ng]

Hi all,

I have a question regarding orientation of engine mounts? The installation in question is a Volvo Penta 2002 in a Fulmar. Friend of mine poked his head in the engine room the other day and immediately remarked that the rear engine mounts were pointing across ships (90 degrees to the engine bearers) and that they should be aligned fore and aft. I replaced the mounts last year and located them the same way they came out. Have I unwittingly installed them incorrectly? Any comparison from similar setups/views on how they should be would be very much appreciated. Also if they are incorrect what is the likely impact on engine and stern gear running?

Thanks in advance.

 

[ccscott49]

If the engine mounts are hard rubber inserted, it make no difference as they are supported all round.

 

[Juggler7823]

On my Fulmar with VP2002 and upgraded to VP2003 the mounts ran along the engine bays.

 

[Amp1ng]

Thanks for the replies.

The mounts are standard volvo parts which are rectangular hard rubber capped with a metal plate that supports the rubber in one plane. The way that I have them oriented means max support is not fore and aft.

I have suffered what I believe to be excessive vibration from the engine in and out of gear and after replacing cutlass bearing, measuring shaft and couplings for trueness and aligning the engine and shaft using 1st principles (with spacers in stern tube) I am rapidly coming to the conclusion that I have overlooked something really simple as to the alignment of mounts according to direction of thrust from the prop. When I replaced them last year I didn't give it a thought that they were originally installed incorrectly and just blindly repeated the same.

I'm hoping this might rectify my long standing issue.

 

[Slowtack]

My VP2003 has a saildrive. There are three engine mounts, two at the forward end of the engine and one aft of the saildrive. The forward mounts are aligned fore and aft. The single rear mount is aligned athwart the boat. I wonder is that also incorrect?

 

[sarabande]

I suspect that if the mounts are aligned with the short axis normal to the thrust direction, the period of oscillation/natural resonance will be shorter than if the long axis is fore and aft.

 

[pvb]

I just replaced the mounts on my 2003T. The plate which screws to the bearers should be fore & aft in direction.

 

[Amp1ng]

Just looked at a Volvo schematic for penta 2002 installation and it shows the rear mounts oriented athwart ships, seems like my hopes of a solution to vibration have been dashed once again. I spoke to the technical department of a Volvo dealer earlier today who advised that the rear mounts should be aligned fore and aft which is what prompted me to ask the question on the forum. What a nightmare, as always never the same answer twice although the general concensus here coupled with the volvo diagram suggest I have the mounts positioned correctly.

Thanks all for your help.

 

[fisherman]

If you want to reduce the vibration put the engine on longitudinal steel angle or channel bearers, then mount the steel bearers on rubber mounts: further fore and aft gives more damping, and/or use three a side. Tip: if the back feet are aligned with the gearbox coupling face it makes shaft alignment really easy.

My old boat had a 4 cyl Ford, the back feet were on the flywheel housing, so was the centre of gravity of the engine (heavy gearbox), so it just gyrated about the back feet. If it wasn't GRP it would have 'shook her leaky'.