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Motor Mount replacement: M25XP

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
We are about to do some serious fall maint. and one of things on the list is reducing the vibration from the engine.
My contact at the boat yard advises that 18 years and 1700 hours of run time would indicate that the original mounts are hardened and no longer doing much to dampen vibrations.
Choices abound.
Buy some unbranded ones from the Universal Westerbeke dealer, or go with the R&D brand from PYI, or Vetus (which is well distributed around here).
I am looking at about $60. each for new mounts, maybe a bit more. Four needed. Labor is the wild card expense, here, if I palm this off onto the yard (at $70. per hour).
What have you guys and gals done? Brand? Cost? DIY? Hired it out?

If it makes a difference, we are going to have the yard do a bottom job next month, and also replace the 11-year-old bellows on the PSS shaft seal. That will probably mean unbolting the shaft anyway.

Thanks,
Loren in PDX
 

cawinter

Member III
Only planning thoughts

Loren,
I looked at the 'problem', having about the same vintage engine and mounts. The two smallest PYI mounts fit as the engine sits about 2 5/8" above the bed. Stud diameter here is about 5/8".

I thought that disconnecting the shaft and maybe some of the hoses (?) should allow you to hoist the engine up enough to swap out the mounts. I was thinking about using the boom (with extra support) and block and tackle for that. Again, just thoughts. My plate is FULL right now.:boohoo:
 

treilley

Sustaining Partner
Don't risk the boom. A 4x4 across the companionway is good for lifting the engine. That is how I did my "in-boat" tranny swap this last summer. I, too am looking at a combination of upgrades surrounding the shaft. I will likely do a PSS seal, new cutlass, flexoflod prop and maybe the flexible shaft coupling.
 

jgarmin098

Member II
I asked my local repair dude about replacing my 18 year old 25XP mounts. He said, "that's a three cylinder isn't it?" I said, "Yes..." He said, "...waste of money. Those 3 bangers are gonna shake and rattle a bunch with new or old mounts. Save your money."

Maybe he just didn't feel much like changing them out for me...
 

ted_reshetiloff

Contributing Partner
Do it youself replacement should not be too bad assuming you can get the old ones out without too much trouble. How rusty are they? A big concern of mine is that the factory mounts are held to the engine beds by lag screw/bolts. The vibration will almost always work them loose. I have thought of trying to get some sort of threaded inserts there to accept machine threads when I replace my mounts. I think the hardest part is the final alignment. Having done a few I know that I suck at it and it is money well spent to have a pro do the aligning. They can get it done in half the time it takes me.
 

chaco

Member III
Cast Mounts

Check out the cast alluminum mounts from www.bushingsinc.com.
Worked fine on my M4-30 (Model DF-2205-2)
The mounts that came with the new Beta where R&D and aren't built as stout. Beta convinced me to use the R&D. Less vibration......more movement :confused:
Will keep the bushingsinc mounts (no-hours) for the future.

Happy Packless Seal :egrin: :egrin:
 

escapade

Inactive Member
motor mount(ed)

Replaced the motor mounts on Escapade last winter. Unbolted shaft from motor, lifted w/come-along attached to 4X4 across companionway. Need extra pair of hands to position engine when lowering back into position. Expoxyed the threads on the rear 2 mounts and welded nuts to the underside of a 1/8 stainless plate for the front motor mount. Bolted plate down with 4 lag bolts epoxyed into the stringers. A worthwile project which only required 1 30-box of "engineering fluid":cheers: . Did not have to remove any hoses or wires. Hit old mounts with liquid wrench a couple time if they are rusty. BTW, this is a M25XP and it still shakes but NOT as bad as it did previously!
Have fun & sail fast
Bud E34 #265 "Escapade":)
 

oldworld

Junior Member
post mount stuffing box/shaft movement

I just finished replacing my 3 motor mounts on my Universal 5424 (3cyl) with bushings.inc mounts: Model DF-2205-2. They are tight (epoxied) with lags in the stringers. Alignment was tedious, but I was able to get all flange points < 0.004 inches.
My issue is now I note about a 1/16th inch of vibration movement in the shaft and stuffing box at lower rpms causing the stuffing box to drip in idle 6 drops/min. As I increase the rpms, the vibration in the aft part of the engine starts to decrease and this movement isn't as noticeable. Any advice, whether this is o.k. or if I should be concerned, is appreciated.
 

Charlie B.

Member II
Motor Mounts

Loren,

If you haven't checked the C34 website for information about motor mounts, it is worth looking at it. They have a lot of good things to say about the Vetus mounts and also a lot of tips about installation. One of the DIYer's described a way to remove and install the mounts without hoisting the engine completely. It involved diassembling the new mount and slipping it in place and reassembling it by inserting the center bolt from above. Removal and alignment is also covered.

By all accounts, it looks like a pretty tough job considering how little room we have in the engine compartment of the Olson 34! :confused:

Good luck and let me know how it turns out.

Charlie
 

Emerald

Moderator
I just finished replacing my 3 motor mounts on my Universal 5424 (3cyl) with bushings.inc mounts: Model DF-2205-2. They are tight (epoxied) with lags in the stringers. Alignment was tedious, but I was able to get all flange points < 0.004 inches.
My issue is now I note about a 1/16th inch of vibration movement in the shaft and stuffing box at lower rpms causing the stuffing box to drip in idle 6 drops/min. As I increase the rpms, the vibration in the aft part of the engine starts to decrease and this movement isn't as noticeable. Any advice, whether this is o.k. or if I should be concerned, is appreciated.

Are you sure you don't have a little offset on the centerline of the shaft hub to gearbox flange? You could have the two planes of the flange and hub parallel within .004, but if the whole engine was slid over ever so slightly, when you bolted them together, you'd end up pulling the shaft over a a hair and get your wiggle. Also, does the drip rate stay the same, increase or decrease with the higher RPM? Spinning up RPM on something like this might make it seem like less play is occuring, but I'd be surprised if that was truly the case. If you can't slide the hub and flange together without having to assist them seating with each other, even if it's just a little wiggle, I'd go fiddle a bit more with it.
 

pick

Member II
Loren,

This was one of the first things I did on my boat (the surveyer thought it would be a good idea). The worst part was getting the bolts on the shaft loose (use antiseize when you reassemble). I think I made a mistake in replacing the mounts with the same type (donut type?) I have since read that these are not as good as the bridge type. My engine has only three mounts, the front one was easy with some small dunnage and a crowbar. After that was replaced I lifted the rear using a large, but cheap, turnbuckle from the hardware store. One side at a time. I also read somewhere that someone placed a deflated basketball under the engine to lift it. Everything depends on the geometry of your situation but I thought that it was a good learning experience and not too tough. The Catalina site mentioned above is good.

Mike
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
First, I found that the rubber in both of the original rear mounts was collapsed flat.
Looking over the scope of work, I chickened out and had the yard do this job for me, last January. They had the boat out for bottom paint anyway.

Interesting procedure -- the mechanic lined up the shaft true from its position in the (new at that time also) cutlass bearing. This then caused the engine to need to be raised up about an inch higher than before.
Sidebar: I had kind of noticed and wondered about the stuffing box hose for years anyway, as it seemed to slightly sag downward... the shaft was not rubbing on the frp alley/log, however, AFAIK.

Some blocks of G10 glass were used as spacers, and the original factory aluminum shorter spacers were replaced. Longer lag bolts went back into the bed logs.
After a couple of allignments, post relaunch, and with some run time... I can only say that it seems to vibrate less at cruise rpm, and, oddly enough, moreso at idle. It does not visibly shake much, but I wish it was quieter.
The slightly-more-expensive R&D mounts were used.

Being a Universal, at idle you always get to listen to the springs in the torque plate rattling, anyway. :rolleyes:

As to the actual mount installation, they told me they lifted the engine one side at a time, and thus did both mounts on that side. Since there is (sort of...) room for a couple of guys to work, and no scratches or damage was done, it must have indeed been muscle power. I guess.

Who me? Clueless? :nerd:

Best,
Loren
ps: picture added of front mounts showing the new frp risers.
 

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newgringo

Member III
Poly Flex Mounts on M25 Helped

A year ago I put the Poly Flex Mounts under my M25 in an E32-3. At the time I was convinced they reduced engine piston rate vibrations into the hull and wrote a post on this site. They were not cheap at about $85 each times 3. The single mount in the front was different, I just installed as the supplier recommended.
 

Gary Peterson

Marine Guy
I believe an important point has been missed. No one has said what the rubber Durometer values of the mounts are. If the mounts are too soft then there can be an engine movement issue and if the Durometer value is too high then there can be too much vibration passing through the stringers to the hull. We did a lot testing where I used to work to acheive the best results with the large diesels we installed in yachts.
If one's engine package originaly had mounts of 70 Durometers then if the replacements had 50 there is going to be a shaft movement issue. Your engine selling distributor should have this information.
 

newgringo

Member III
Gary,
Good point. Stiffness does matter. And then there is the issue of transmissability where different mounts with similar durometer elastomers allow different amounts of vibration energy into the hull. Has something to do with the material hysteresis and damping ability. Gets technical and the various manufacturers are indeed proud of products they know perform well. Years ago I got deeply involved with this issue for a turbine engine application. Two very qualified mount manufacturers proposed similar stiffness products but tested very differently when instrumented with accelerometers and spectrum analyzers. How we sort this out for our boats is not clear and I guess we have to rely on their test data and the experience of mechanics and fellow boaters.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Oh My.....

:egrin:
Jerry,
If a person were to read your post without knowing the subject... this would rank as one of the funnier collections of double ententres in the history of this web site!
:rolleyes:

Thanks for a good laugh (albeit unintended) on a cold and wet day!
Cheers,
Loren in rainy Porland
 

Gary Peterson

Marine Guy
Guys,
What we, as boaters, have to worry about on mounts, is when we install them is to make sure there is no binding in the mounts and they are parallel to the stringers and exactly vertical to the crankshaft center line.
The engineering that goes into mounts (or more precisely called ISOLATORS) will take into consideration radial, axial, and thrust forces that the engine will create. While our sailboat engines don't produce much thrust, much larger diesels (ie) > 2000 BHP produce considerable thrust that is very hard to engineer for.
 

mkollerjr

Member III
Blogs Author
re: yanmar

Hello,

I have a Yanmar 3HM in my 1990 E38. The mounts were replaced by the PO about 8 years ago, and they still look ok. However, I think Yanmar recommends they be replaced about very 5 yrs (I need to verify this). They look simple enough to replace though. There are bolts on each of the four mounts that you use to raise the engine just enough to slide in a new rubber isolator. Here's a good link: http://www.oceannavigator.com/November-December-2012/Replacing-engine-mounts/

Thanks,
Mark
 
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