motor mounts replacement cost

[alman]

I believe my motor mounts need replacing. There is more noise and vibration lately. I have no idea how old they are, but assuming more than 15 years old.

Not going to be able to tackle that myself.....but wondering what is the average cost for such a job?

[arf145]

What engine? What boat? Any other details?

[alman]

yanmar 3 GM30F

'82 Allmand 31'

[btrayfors]

Originally Posted by alman

I believe my motor mounts need replacing. There is more noise and vibration lately. I have no idea how old they are, but assuming more than 15 years old.

Not going to be able to tackle that myself.....but wondering what is the average cost for such a job?

Can't speak to your Yanmar, but here are the costs for my Perkins 4-108 in mid-2007:

4 new motor mounts.......$191.84

labor to change 4 mounts, remove short jack shaft and check for alignment, new bolts for Drive Saver, reinstall and check overall alignment.....$477.35

Total.....$669.19

Your mileage may vary :-)

Bill

[T37SOLARE]

Bill,

Can I ask who you used for the mounts? I got a quote from one of the shops at HHN and it was astronomically out of this world.

[btrayfors]

I got the mounts on a special deal from Aric at Rockhold Creek (Chesapeake Marine Engineering), just as I was ready to leave for Maine.

Had them installed by Journey's End Marina in Rockland on Penobscot Bay. A wonderful boatyard where I've based for two summers cruising Maine!

Bill

[arf145]

The Yanmar mounts are something like $130 a piece--at least they were for our 2GM. Assuming nothing else is discovered--as happened in my case--I think the labor in my area might have been something like what btrayfors reports. Really depends.

[bwindrope]

I take your desire not to do it yourself at face value, and by all means that is probably a wise choice since you know yourself best. But I would like to put a plug in here for doing it yourself as I did recently and it was not bad at all.

Besides the money savings, which is substantial, I found doing it myself gave me a chance to look at things and understand my mounts in ways I wouldn't have. I couple 2X4's sistered together and a standard come along where all it took to lift the diesel on my Gulf 32.

This reflects my bias a bit, but I think this is one of those jobs where you are rolling the dice with someone else doing it. The shaft alignment is the most difficult thing, and since you are going to clearances in range of .001 inches, you must get it right. A ballpark, good enough approach that some commercial outfits will use will not be good enough for you a few hundred hours later when your shaft is ruined.

Anyway, for anyone thinking about doing this themselves, here is a link to my boat blog where I describe it with a few pictures. There is another post after this one when the job was done.

Stories of Aeolus- Our Gulf 32 Pilothouse: Replacing engine mounts

Stories of Aeolus- Our Gulf 32 Pilothouse: Engine alignment and other reconnecting tasks

Good luck with getting yours done. And pay special attention to the shaft alignment. Read Calder if you haven't.

[foggysail]

I have comments I want to make regarding motor mounts.

Motor mounts fall into the category of vibration isolators. Isolators are designed to dampen (attenuate) vibrations of particular frequencies or range of frequencies although the higher frequencies are easier to dampen. Low frequencies such as found on single cylinder engines are a real dog to dampen. Further, the isolators are designed for a weight range and also a thrust limit. It would really be nice if boat engines were protected from the thrust load (horizontal force vectors) with a thrust bearing on the prop shaft. I have not seen any on the size boats I have been on although I would believe larger boats use them.

Isolators also have their own resonant frequencies. If there is an engine caused vibration frequency that happens to also be an isolator's resonant frequency, that frequency will not be attenuated, it can in fact be made much worse.

One other comment that I want to make regards to so called "fit all" mount with an adjustable threaded bolt. The horizontal forces on the mount will use the mounting height as a lever. One can minimize this problem by trying to raise the height of the entire isolator (engine mount) and not just use the mounts adjustment. And of course we all understand that the prop is going to provide that horizontal force vector.

OK--- I understand that most folks are just going to order replacement mounts and install them or pay to have them installed. But what you get is what you get and just maybe there is an isolator better designed for the job. The real problem is finding a manufacturer who will share his product's data sheets with the load and frequency characteristic curves.

Years ago I purchased a 30 Hunter (1979) that used a single cylinder horizontal mounted piston. What a dog! The life lines on my boat vibrated at their natural frequencies when under engine power. They vibrated as much as 6or more inches!!! Everything in that boat seemed to move. I redesigned the engine mounting system with new mounts which I matched as best I could to frequency attenuation, loading weight and horizontal thrust. I was able to get rid of most of teh vibrations that calmed the life lines and door rattling. A few years later, I replaced the engine itself with a Kubota 2 cylinder.

Foggy

[Shortman]

On my 85 Pearson 34. Done by Williams Boat on Mt Desert Is, ME spring 09. 4 mounts $535, labor $325 + misc = $915.
I asked about fancier vibration dampening mounts, knowing the Yanmar OEM to be very pricey, to which they pointed out difficulties of alignment by varying from original. Would have req'd structural changes in engine "room". $$
Also I believe there's potential problems straying from original mount design with issues discussed by foggysail. Didn't want to subject my "24 year old still in good shape (knock on wood) original" engine to different stressed & strains. Some of us don't react well to new stresses & strains.