Engine mount question(s)

[Peter]

With the Yanmar 2GMF out of the Albin Vega, I'm making all kinds of discoveries. The boat originally had an Albin 'Petrol' engine, and was converted to Diesel by a professional outfit.

One is that the rear mount brackets that bolt to the gear box were modified, moving them 1" outboard and 2" higher than the original configuration. Looking at the engine beds I can see this was necessary to provide hull clearance ... there just isn't room for the original layout.

So then I find this article extolling the foolishness of making just such a change.
Hmmmm .... I need new mounts anyway, so do I just replace with the original style mounts and leave well enough alone? ... after all, it lasted 23 years and was still working when I took it out (there's got to be a lesson there)
OR
do I look at an alternative type mount, modify the engine beds, and restore the geometry specified in the engine installation guide?

One other thing I found is the starboard rear bolt in the engine bed is badly rusted, due probably to a leaking raw water connection above it. The beds appear to have been modified when the Diesel conversion was made, and I'm wondering what holds these studs in place. What is the usual method of attachment?

Decisions decisions :-)

As always, any and all help is much appreciated!

[Tim]

I would stick with the rubbery Yanmar flex mounts, myself. They are designed as they are for a reason, and they work--very well, in fact.

The alternative mount you linked is not that impressive. I've used those, and don't think that much of them. They provide very little flexibility. You're better off with the Yanmar mounts, in my opinion. They're a designed-in part of the engine system. (Plus, I hate how those upturned "cups" in the other mounts you pictured capture water, debris, etc.)

While it may not have been the right choice to modify the engine mounting flanges they way they were on your engine, it certainly worked. Probably, the Yanmar should have originally been pulled forward enough to allow for the proper clearance, but this would have surely required extensive engine bed modifications, as well as interior cabinetry changes. It's understandable (if not laudable) why it was done the way it was.

I was interested to read the article you pointed out, and although I'd never have considered changing the actual engine flanges myself, it was interesting to read about why it might be a bad idea. Despite that, it seems that your installation was satisfactory all this time, and I'd have to say that it's probably OK to keep things the way they are on this current installation.

Do you have pictures of the engine and these flanges, as well as its hull foundations? It'd be interesting and helpful to see the situations at hand.

A photo of your rusted stud and surrounding area might help determine how your setup is put together. I don't know what your engine foundations are made of, or how they're laid out, etc. It's possible that the stud is threaded in somehow, or perhaps secured in place with epoxy or other adhesive, or welded to a metal foundation, or even just a through bolt from the bottom that was inserted before the foundations were permanently secured.

[Peter]

A little time giving things a "wire wheel rebuild" and here are some pictures:

This is the rear right side of the engine showing the modified bracket that moves the mount up about 2" and out about 1"


This is a shot of the engine beds, looking aft. (The shaft tube is off center to miss the rudder post.)


This shot is of the mounts in place.


This is the rear mount rear bolt. It's corroded where it protruded through the nut, but is otherwise ok. It goes to show I should clean things up before hitting the panic button! There are no cracks in the beds or other signs of the bolts being in danger of pulling out, so it looks like the best plan is to replace the mounts and leave well enough alone.

[The Good Goose]

Peter
Did the old mounts fail? I have the same ones and was curious what the lifespan is and if they were prone to a particular kind of failure.

Brock

[Peter]

Brock:
The two mounts shown in the picture are the front ones. The rear ones are a mass of flaking rust as the exhaust system leaked on them for many years (before I bought the boat and replaced it).


The rubber is peeling off and it's only a matter of time before they let go.
Otherwise, the front mounts, after a little clean up, appear to be in good condition, so I don't think you have to worry about yours.

[Tim]

Peter,

I don't see any reason why you shouldn't just reinstall the engine using the existing foundations, modified brackets and all. It looks like a decent execution that has held up well over the years, and despite the warnings issued by that website you found, it's clear that your setup has worked without significant problem.

I'm not one to let ride installations that are lousy or half-cocked, but in your case the modifications seem to have been done well, and lacking a real reason to tear everything out and start fresh (i.e. something like cracking fiberglass on the foundations, or seriously corroded mounting studs), I believe you'd just be making a whole lot of unnecessary work for yourself. Considering what might be involved in returning the engine to its original mounting flanges, such as a requirement to pull the engine significantely forward to provide clearance, I think you're best off leaving well enough alone.

Did the old mounts fail? I have the same ones and was curious what the lifespan is and if they were prone to a particular kind of failure.

FWIW, the Yanmar mounts do tend to lose their elasticity properties over time, but there are no hard and fast rules governing how long they last, or don't last. Typically, when the rubber starts to go, the aft mounts will begin to sag and provide a clear visual indication that replacement is necessary. But the usual mechanism of premature failure tends to be corrosion of the steel portion of the mounts.

If the rubber loses its correct properties, the engine can quickly fall out of alignment, which compounds the problem and causes a host of new problems if left unchecked.

[Peter]

I don't see any reason why you shouldn't just reinstall the engine using the existing foundations, modified brackets and all.

I agree. As my wife reminded me, "It's an auxiliary engine ... we're mostly sailing!"