Hunter 29.5 2GM engine vibration

[BigEasy]

Ralph,
I can't explain the discrepancy between the Yanmar & Ellebogen mount recommendations (fore / aft placement).
I can verify, with certainty, that the original Yanmar (3YM30) mounts installed at the Beneteau factory were 100 shore rating installed forward & 75 shore rating installed aft. Just verify for your application when you remove old mounts.
A few tips for this job:
Disconnect transmission flange & shaft coupling. Support shaft with scrap lumber.
Loosen top locking nuts on mounts.
Mark position of existing mounts on FRP stringers.
Place scissor type jack under engine with wood buffer between jack & oil pan. Do not have to raise engine, just support.
Remove nuts/bolts from base of engine mount.
Remove bolts that attach mounts to bracket on side of engine & slide mount & bracket assembly out horizontally.
Set new bracket slightly higher than old mount. Note position of slot in old mount. Slide back into place & secure bracket / mount
assembly to side of engine.
Super glue fender washer & nyloc nut together & place into box end wrench to ease installation of bolt & backing nut. Lubricate bolt.
Complete one mount before proceeding to next mount to minimize engine movement for easier alignment.
Remove jack & perform initial alignment, followed by fine tuning after a few days later, in water, to allow settling of new mounts.
Tighten lock nuts on top of engine mounts.
If access to the mounts & backing nuts is reasonable, this isn't a difficult job. If access is very limited, as in my case, it is a PIA.
One or two man job, again, depending on ease of access. I did this with boat in water. Good luck!

 

[BigEasy]

My good sir, I leave the positioning of motor mounts in your capable hands. Please don't leave me hanging .

Ralph,
See Ellebogen invoice in above post. I did not notice any difference in dimensions between the Yanmar & Ellebogen mounts; they appeared exactly the same.

 

[Brian M H23]

this was definitely my issue, all of them had rubber/metal separation and both starboard mounts had failed completely. I'm not sure how this guy was getting around, but the leaking gland and worn cutlass probably all caused by these failing.

Changed out the mounts yesterday. Really not a bad job, couple hours including re alignment. I didn't need to disconnect the shaft.

I ended up using these mounts in all 4 corners - This mount design is already quite compliant; it's hard to imagine putting 2 slightly softer ones in would make a huge difference. I'll let you all know when the boat shakes apart .

No time to get out on the water yesterday , but motor operation in gear against the dock lines was vastly improved. Getting there!

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[Brian M H23]

My good sir, I leave the positioning of motor mounts in your capable hands.

Based on specifications from both Ellebogen and Yanmar I offer the following :

View attachment 231533
Ellebogen


View attachment 231534
Yanmar Parts Catalogue



View attachment 231536
Purchase of Aft Starboard Mount in 2009
​

Check the parts numbers. My purchase in 2009 and the Yanmar parts catalogue show the same parts number. The Ellebogen parts numbers disagree. I am still looking for a paragraph in a Yanmar catalogue in which the Ellebogen and the Yanmar parts catalogue agree.

@BigEasy , I'm relying on you for the correct location of these mounts as I'm getting ready to replace the mounts on my 2GM20F with Ellebogen mounts next winter.

Please don't leave me hanging .

I came across the same discrepancy. The front mounts seem to be quite a bit more loaded than the rear, I would not put the soft ones forward despite yanmar and hunter documents that might suggest it.
I suspect the benefit of softer mount in rear makes the drivetrain more tolerant of misalignment, allowing the transmission to move around, or maybe some nuanced reduction in prop vibration to the hull.
I personally went with the 2gm20f(v) setup, 4x100, and can't imagine any significant downside, even though this isn't a vee drive. I certainly don't want it wiggling around even more than it can right now...

 

[Brian M H23]

Update all! Had a successful memorial day first outing. Motored out, sailed barnegat bay for a few hours. Some issues with the furling drum line jamming that a new line will fix, head only kind-of flushes. Expected kinks to work out on a new, used, boat.

As for the vibes

I don't have a good baseline on how much vibration is normal - but things were vastly improved from pre- engine mounts. Low rpm shakes a bit (motor - same idle or in gear), 1600-2100 under load purrs right along perfect, higher RPM feels like something coming synced prop or shaft (original 2 blade AFAIK, I didn't touch it) but nothing seriously concerning. The flex coupler did move the prop an inch farther away from the strut (but I needed to move the packing gland to a new, unworn place on the shaft, and the transmission flange had a little axial runout that the flex coupler makes a nonissue)

Tweaked the packing (3 rings of graphite /teflon) to get a tiny bit of water underway, no apparent leak with the shaft stopped. It's very sensitive; no wrench needed to completely stop the water. Assume that means I did a good job on my rings?? The whole inboard thing is new to me.

Cheers to a summer on the water (and learning a boat 3x as heavy as my old 23)

 

[Ralph Johnstone]

It's very sensitive; no wrench needed to completely stop the water. Assume that means I did a good job on my rings??

Right on the money. Gets a little stiffer as the corrosion grabs hold.

As spreviously mentioned, SEND US A VID. WITH THE ENGINE IN NEUTRAL and run from idle to 3600 RPM and we'll tell you what's causing your vibration.

If I get time, I'll send you a vid. of my 27 year old engine with original mounts. Minimum vibration. OCD is not all bad.

 

[Brian M H23]

Right on the money. Gets a little stiffer as the corrosion grabs hold.

As spreviously mentioned, SEND US A VID. WITH THE ENGINE IN NEUTRAL and run from idle to 3600 RPM and we'll tell you what's causing your vibration.

If I get time, I'll send you a vid. of my 27 year old engine with original mounts. Minimum vibration. OCD is not all bad.

Sorry, no video, but have gotten some sea time with the boat this summer. Engine purrs in neutral, no concerns there. Sailing in neutral, you can feel some vibration coming from the driveline as the shaft spins. The new mounts settled in and it could use a little tweak to the alignment, for sure.
I also realize I stuck a zinc on the prop shaft well away from the cutlass, which is apparently not good, especially if there's any bow in the shaft. Also completely unsure if the prob is well balanced; I didn't do anything at all to it, even clean it, before launch. To make the situation worse, this photo isn't even the final setup; I'm fairly certain with everything in place there's another inch of shaft (making it closer to 3" total) sticking behind the cutless before the prop; far too much overhang for a 2 blade prop on a 1 inch shaft..

 

[Brian M H23]

And just to make clear.. The reason I added a spacer in the coupling was to deal with two other issues, primarily that the cutless was beat, stuffing box was over tightened and wore a groove in the shaft. For a pre-launch job on a boat I bought end of season and didn't know much about (except that it leaked at the box), it's a huge improvement.

It's looking like a new shaft and a 3 blade prop may be in my future, though.