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Failed Engine Mounts

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Category: Hints & Tips
Forum Name: 400
Forum Description: 400 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=3186
Printed Date: 28 March 2024 at 18:48
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Topic: Failed Engine Mounts
Posted By: landlocked
Subject: Failed Engine Mounts
Date Posted: 28 July 2009 at 07:20
On the first day of our summer holiday this year my wife remarked that the engine was making some different noises.  I went below and found it was making some different movements as well - jumping around a bit.   It turns out both of the forward engine mounts had failed, so the engine was only supported by the aft engine mount and the sail drive gasket. 
 
Fortunately it had been a good day for sailing and we were almost in port when I found the problem.  Also fortunately there was a marine mechanic on shore and working on Saturday who welded new studs on my engine mounts so I could carry on until I got the right parts a few days later.
 
Here's what I learned:
 
1.  The mounts appeared to be installed as specified by Yanmar and the bed for the engine is supplied by Yanmar and glassed in place at the Hanse factory.
2.  This has happened on other (non Hanse) boats with the 3JH4E engine and SD50 saildrive   http://www.sailnet.com/forums/gear-maintenance/25659-need-help-yanmar-engine-mount.html - http://www.sailnet.com/forums/gear-maintenance/25659-need-help-yanmar-engine-mount.html
3.  The mounts are different (stiffer) if you have a saildrive rather than marine drive (and not all dealers realize this!!).  9 bus rides, 1 ferry, 1 taxi and 1 "lift" from a friend and I finally had the right parts ("200" rating).
4.  The failure was a fatigue fracture of the threaded stud on top of the mount, and not too surprising given the vulnerability of this design (more on this below)
5.  Access through the side panels of the engine compartment is great.  Thank God.
6.  If you remove the companionway steps the main halyard can come straight down to the lifting ring on top of the engine.  Thank God again.
7.  Removing the companionway steps could be much easier if you didn't have to access the nuts on the back of the bolts that hold the hinges (maybe epoxy them in place for next time?)
 
Here's some more about the failure mechanism:
 
The bolts failed immediately below the nut that supports the engine tabs (I have a photo but can't seem to upload right now).
 
According to my mechanical engineering friends, threaded rods should only be used as fasteners and not structural members as they are in this case.  They can fatigue very easily if subjected to flexing forces.  This is because when you bend a threaded rod the strain is not evenly distributed across its length but rather concentrated in the valleys of the threads.  It's much like the effect of a nick in a wire - the rest of the wire is stiffer so when you bend it, most of the deformation happens in the nicked part and it quickly fatigues.  In the case of the threaded rod you really have a series of nicks that take up the strain of the flexing, instead of having it distributed evenly across the rod.  I was shocked at first to see these thick bolts had broken, but now that I think of them as vibrating rods with cracks encircling them it isn't at all surprising.  In my photos that you can't see just yet, it is clear that the fractures happened along the inside of the first thread below the nut that supports the engine (the first nick in the wire so to speak).
 
I expect that the higher you place the engine on the stud the quicker it will fail, and it may be that the 3JH4E/SD50 arrangement is a bit worse than most, and maybe mine were a millimeter or two higher than most.
 
The solutions that were suggested independently from two different sources were to put some kind of spacer between the top of the engine mount and the engine tab which will bear the strains from the vibration while the threaded rod is used only to clamp the engine down onto the spacer.  I have improvised such a solution for now (photo to follow), but will also take this up with Yanmar.
 
My advice is to beware.  Maybe even carry an extra pair of 200-rated Yanmar flex mounts (about US$208 each).  You may have a ticking time bomb in your engine compartment.
 


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"Kerkyra" 400e #042



Replies:
Posted By: landlocked
Date Posted: 28 July 2009 at 07:30
 
Engine mount and lower part of stud in foreground, engine tab and upper part of stud in background (the engine shifted to starboard and dropped down to rest on the top of the engine mount)


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"Kerkyra" 400e #042


Posted By: landlocked
Date Posted: 29 July 2009 at 04:09
 
Closeup of failed surface.


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"Kerkyra" 400e #042


Posted By: landlocked
Date Posted: 29 July 2009 at 04:19
 
After removing broken engine mount


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"Kerkyra" 400e #042


Posted By: landlocked
Date Posted: 29 July 2009 at 04:40
 
This is the new replacement mount


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"Kerkyra" 400e #042


Posted By: landlocked
Date Posted: 29 July 2009 at 05:08
 
Modified assembly. 
 
The stud is a sort of carriage bolt that passes through the top part of the mount and is normally fastened in place with a nut and lock washer (painted black).  In the photo above I have removed the nut and lock washer, placed an oversized nut and flat washer around the stud as a spacer, and then replaced the (black) nut and lock washer and tightened it down on the spacers.  I then sat the engine on the black nut and tightened the final nut and lock washer on top of the engine tab.  I think this should reduce the flexing of the stud.
 
If anybody thinks this is a bad idea, please let me know your thoughts. 


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"Kerkyra" 400e #042


Posted By: panos
Date Posted: 29 July 2009 at 18:51
Hi,
Good job.
But I suspect that you cured the symptom and the cause is still there. I think that the cause of failure was intense vibrations caused by either engine malfunction or load misalignment.
I dont think that these huge bolts would fail under normal conditions (even though the surface mark theory is correct, but only marginally reducing the shear strength of the bolt)


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Panos

Hanse 630e - selling her -


Posted By: landlocked
Date Posted: 29 July 2009 at 19:54

I guess you're right that there must be a reason for mine to fail when others haven't (though apparently some others have), but I suspect that all of these installations are subject to the same failure.  It could be that the design is marginal so that depending on normal variations in manufacturing and installation some are more prone than others.

It could also be that something caused an increase in vibrations as you pointed out, and this brought on the failure.  I have a 3-blade prop which should cause less vibration than a 2-blade but it is also a folding prop and I suppose if it didn't fully unfold or if a stray piece of rope or something caught on the prop the vibrations could increase.   Still, it seems to me that there should be enough margin in the design of the engine mounts to handle this.  
 
My concern is that there is a "weak link" in the engine mount design which is the length of threaded rod coupling the engine to the mount, and I suspect that this is the component that limits the overall reliability of the mounting system.


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"Kerkyra" 400e #042


Posted By: Captain Cook
Date Posted: 17 June 2017 at 21:13

I would like to add some information to this old topic from 2009.
My engine mounts broke in rough weather at sea between Sealand and Germany in the summer of 2012. I made a temporary repair at sea, and on arrival in Kiel, I ordered new mounts at the local engine-mount pusher (680euro) and replaced them. Later in 2012 I also replaced the rubber-diaphragm that support the SD50 saildrive. While sailing with broken mounts, the diaphragm had carried more load than designed for (and you should change it anyway after 7+ years???).
During the repair I was in contact with the danish Yanmar-agent, and he told that it was an error to place the engine on the mount with the upper nut at top of the thread. There should be 8-10 mm visible thread over the top of the upper nut. As can be seen on the picures from Landlocked, and on my pictures, Hanse werft has placed the engine with less than 1 mm of thread visible on his and mine boat. You will also notice a steel-wire with wire-clamps on securing the mount against severe movement. This is for use in rough seas. As can be seen, as Landlocked did, I reinforced the assembly a bit by stacking the nuts and strenghtening it with blue loctite. Until now - it works. Take a look at my upper nut and compare it with yours - as you can see I took faith in the advice I recieved from Yanmar - and placed the nut (and the engine) lower.










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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: Captain Cook
Date Posted: 18 June 2017 at 10:53

A few pictures more:





The big nut on the mount is placed there after removal - it is adding confusion -it should not be there.



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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: Captain Cook
Date Posted: 20 June 2017 at 10:48
As I explained to Dråpen in a PM, the nuts are of two different sizes.
The new mount is delivered with a small nut at the bottom of the bolt.
On top of this nut I put a large nut and a washer, then the engine foot, and then a washer, a spring washer and a large nut. All liberally soaked in blue Loctite. (see photos)
The extra large nut I got from the old broken engine mount.

A hint to the correct position of the engine foot/feet can be seen on the technical drawings in the background of two of the photos. here you can see about 8 mm free thread from the foot to the nut.


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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: landlocked
Date Posted: 16 September 2017 at 19:43
I just noticed this added post from Captain Cook, showing the same type of engine mount failure I had on my Hanse400.   FYI, the original mounts failed after 3 years and the replacement mounts with my slightly modified installation are still good after 8 years.   I still feel that the practice of using threaded studs as a "structural element" that flexes with engine vibration is not good, and they should only be used as a threaded attachment for tightening the engine down onto another structural element such as a standoff (in my case I used an oversized nut).
I often wonder what would have happened if this failure had precipitated something worse, like breaking the third and only remaining engine mount, and/or tearing the rubber seal on the saildrive.


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"Kerkyra" 400e #042


Posted By: samuel
Date Posted: 17 September 2017 at 09:48
Surely if one is worried about the length of the stud being such that it a allowed to flex the answer would be to place a steel plate ( a piece of gauge plate being best) under the engine mount so that the engine mount itself was higher. Then one would just put 2 longer bolts into the bed & use less of the top stud.


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Daydream Believer- Hanse 311- No GBR9917T- Bradwell Essex


Posted By: landlocked
Date Posted: 17 September 2017 at 15:38
I don't recommend adding a spacer under the engine mount, and using less of the stud, as this would change the damping effect of the engine mount. Yanmar specifies the height of the fibreglass foundation, the nut location on the stud, and the rating of the rubber material in the mount.   Presumably this is all with consideration of how it will dampen the vibrations for the specific engine and saildrive.   Personally, I would not deviate from that without an endorsement from Yanmar.   
I think that, rather than specify a height for the nut location, Yanmar should supply a standoff at the correct height, which you just insert on the stud. Bolting the engine onto the standoff instead of suspending it on the stud would solve the fatigue problem.

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"Kerkyra" 400e #042


Posted By: samuel
Date Posted: 17 September 2017 at 19:18
Originally posted by landlocked landlocked wrote:

I don't recommend adding a spacer under the engine mount, and using less of the stud, as this would change the damping effect of the engine mount. Yanmar specifies the height of the fibreglass foundation, the nut location on the stud, and the rating of the rubber material in the mount.   Presumably this is all with consideration of how it will dampen the vibrations for the specific engine and saildrive.   Personally, I would not deviate from that without an endorsement from Yanmar.   
I think that, rather than specify a height for the nut location, Yanmar should supply a standoff at the correct height, which you just insert on the stud. Bolting the engine onto the standoff instead of suspending it on the stud would solve the fatigue problem.


But in the earlier thread you pointed out that Yanmar's recommendations ( ie threaded stud used as a structural element) did not work because the original installation broke - did it not?
So on that basis one would not really hold a lot of faith with their recommendations!!!


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Daydream Believer- Hanse 311- No GBR9917T- Bradwell Essex


Posted By: landlocked
Date Posted: 17 September 2017 at 22:03
Ya, I don't like their recommendations about using the stud as a structural element, because it fatigues and fails, with nasty consequences, on a number of boats.   It seems prudent to take measures to prevent that, and I wish Yanmar would look into this themselves.
I would still stick to their mounting dimensions though, since presumably they've done more engineering work on that than you or I.  I guess I don't see this as a matter of faith, just logic.



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"Kerkyra" 400e #042


Posted By: Angelina
Date Posted: 10 August 2019 at 17:45
Hi All,
Seems to have gone quiet on the failed mounts.
Could someone pls describe how the vibration mounts were changed?
Lift the engine up, unscrew the engine brackets, then
slot in the vibration mount?
Or simply lift the engine high enough with the help of the boom to be able to slide in the vibration mounts without actually having to remove the barely accessable
engine brackets?
Can the saildrive seal take all that lifting of the engine?
Thanks Very much. G.


Posted By: landlocked
Date Posted: 10 August 2019 at 18:29
In my case I did this:
1. Removed companionway steps by unscrewing hinges
2. Connected main halyard directly to the hoisting eye on top of the engine
3. Lifted engine enough to slide the two forward mounts out sideways (slide the bottom sideways and drop them out)
4. Reverse process to put in new mounts.

I left the aft mount connected and the amount of movement was small enough that it didn’t strain the saildrive seal or rear mount.  The halyard had a direct line to the engine lifting eye without interfering with anything so I didn’t use the boom, just the direct halyard connection.

I did this three times, first with repaired (welded) mounts as a temporary measure and again when I reached a port where I could buy new mounts, then again when I modified the connection by adding some oversized nuts to serve as standoffs to prevent the fatigue failure of the studs.

Incidentally, I still have the modification in place — It has been like that for 10 years now without problems.


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"Kerkyra" 400e #042


Posted By: Captain Cook
Date Posted: 10 August 2019 at 20:24

As you can read in my post above, Yanmar in Denmark tells, that HanseWerft has mounted the engine at the top of the thread, which maybe is the reason for the metal-fatigue.
Anyway, both my engine mounts broke in rough weather, and I had to make a temporary repair. When I recieved the new mounts (In Kiel, 100 Nm from my own harbour), I used a piece of 22 mm plywood (120x20 cm) to support the engine when the mounts were changed. I used another plywood as a lever to lift up the engine when needed. The work lasted a few hours, and did not call for any special skills. Any sailor with one left-, and one right hand should be qualified.
As for your remark  on "barely accessible" mounts, I do not agree, The mounts are easily accessible, just look at my photos above.(I naturally removed the cover under the stairs,-4 screws).
You wonder, if the saildrive seal/diaphragm will survive the movement of the engine. I can inform you, that behind the saildrive there is a third mount, so the engine is not suspended in the diaphragm, when the two mounts are broken.
I changed the diaphragm later on, but I do not know, if Kerkyra did that as well.
I have mentioned earlier, that in the background of a pair of my photos, there is an official drawing from Yanmar, which clearly shows, that the way I mounted the nuts, are correct. There is a gap of 8-10 mm between the flap on the engine and the top nut. That tells you there should be 8-10 mm visible thread over the upper nut. I seem to have lost the drawing, and can not find it again on the net.




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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: Angelina
Date Posted: 11 August 2019 at 07:02
Guys,
I am new here.
Did not intend any harm.
Asked a simple question in reply to a post.
Appreciate all that participate and take the trouble to write.
I do have the same problem, boat built ‘09 and in the water since.
No further required or of interest?
PM if you like.
Even if I was a troll, so what?
This forum is to relay information. To whom it may concern.
Let’s sail. Or try to!


Posted By: Captain Cook
Date Posted: 11 August 2019 at 18:38
Hi Gordon (Angelina)
Welcome to the forum, but beware of old-timers with no sense of humorTongue.
As reply to your questions on PM:
1) No I did not loosen the aft mount - but feel free to do so, it can do no harm. (Difficult to access though).
2) The engine only needs to be lifted a few centimeters. Just angle the new mount a little when mounting it. In my photo you can see that I marked the position of the old mount with blue speed-marker.
3) The oil pan is made of iron, so I had no qualms to lift it with a broad piece of plywood. I was 100 Nm from home, and needed to use the tools available to me.
4) I changed the diaphragm because I planned an ocean crossing. I did not know, what stress it had suffered, when the engine was dancing rhumba in the engine room. In an older post of mine there is a photo of the old diaphragm, it feels and looks just like the new one. I would not be nervous to mount the old one again. The mechanic also checked the aft engine mount, and said that it was as good as new.
Good luck with the repair!
Kjeld

Update march 2024: 12 years have passed, and my repair and "upgrade" with a few extra nuts and blue Loctite is still working. I recall, that the reason I did not lift the engine in the lifting ring, was that this ring is placed over the engines center of gravity, so the engine will stay horizontal when lifted there. I wanted to raise only the front of the engine, so that brought forward the pieces of plywood. First I stabilized the engine with the broad piece, and then I used the slimmer piece underneath this (as a lever) to lift the engine when needed.


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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: Captain Cook
Date Posted: 11 August 2019 at 21:29
In this forum I only remember to have seen the breaking of the engine-mounts bolts mentioned by Landlocked, myself, and now Angelina. Out there there may be other Hanse owners with one or two broken bolts. If you study the pictures of my bolts, it seems that one is corroded on the breaking surface, meaning that one bolt was broken some time before the other also broke.
In my case, I normally check my engine room at intervals when sailing, more often when the weather is bad. In 2012 I were sailing by engine and the main in 3rd reef between Denmark and Germany in some 14-16 m/s or 30-34 knots, and when I lifted the stairs, I noticed the engine periodically lifting 5-10 cm in one side, when we were thrown around in the heavy waves. I throttled down, and at lowest safe speed I used a pair of endless clamping straps to secure the engine to the mounts. Then I found the nearest harbour.
The lesson to learn is, that one mount was broken for some time, and as you can see in the photos, the engine was fallen down to a position, where it rested quite nicely if you only sailed in calm weather. I will recommend, that you check this next time you visit your boat. To check if only one mount is broken, you have to use a lever to lift the engine in one side, and then the other.
As Landlocked is writing, this failure is known to other brands than Hanse.

With the knowledge I have obtained about this, I will recommend, that you buy a couple of nuts, and a pint of Loctite, and change your engine mounts to a look-a-like of what Landlocked and I have made.
Back in 2012 I found a recommendation from Yanmar to secure the engine to the mounts by way of mounting a steel-wire with clamps as seen in my photo on page 1 of this thread. This should be a precaution if the mount broke when sailing in heavy weather. This way the engine would be restricted from moving very far from the mount. I will try to search the net for the recommendation.
:Kjeld


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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: landlocked
Date Posted: 12 August 2019 at 01:17
I agree with Captain Cook that the installation of these mounts should be modified such that the threaded rod is not being used as a structural member.  It should only be used to clamp the engine bracket onto another structural member (nut, spacer, washer, etc).

When the threaded stud is used as a structural member in this way it is subjected to a bending stress which is concentrated on the vertex of the first “exposed” inside thread (below the engine bracket).  A crack develops in the thread and migrates through the stud until it fails.  How long this takes probably depends on a lot of uncontrolled factors, like the condition of the die that cut the thread, or the microscopic structure at that particular part of that thread.  Just google “threaded rod as structural member” and you will find documents like this one  http://www.aefac.org.au/documents/AEFAC-Pub01-threaded-bar.pdf" rel="nofollow - http://www.aefac.org.au/documents/AEFAC-Pub01-threaded-bar.pdf
Here is a quote from the section titled ‘Important Conditions’:
“Threaded bar in its own right is not an ideal structural member. The threads act as notches and when subject to bending, material failure could occur at a lower load than that for a smooth bar due to stress concentrations associated with thread roots. The same reason makes threaded bars not suitable for dynamic load applications where they could be subject to premature fatigue failure. Furthermore, when the strength of the bar increases, its susceptibility to brittle fracture and fatigue failure also increases.”

I think this can easily be solved but unfortunately Yanmar seems to deny the problem.  They told me their engine mounts don’t break and I must have crashed my saildrive into something with enough force to shear off both of the shock-mounted bolts.  I told them there was no collision but they prefer to call me a liar than to review their design.  To me, this is pure negligence because it is a clearly deficient design with a history of failures, a safety risk, and an easy remedy, but they are ignoring it.


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"Kerkyra" 400e #042


Posted By: Mark_J1
Date Posted: 14 August 2019 at 00:50
This topic surfaces repeatedly. Worth emphasising it’s a common Yanmar issue not a Hanse problem. See http://www.myhanse.com/engine-mounts_topic6573_page1.html" rel="nofollow - http://www.myhanse.com/engine-mounts_topic6573_page1.html for some additional thoughts and analysis. 

One thing I’d add to my comments in the earlier thread.  Subsequent to the engine mounts failure and change we also did a saildrive inner diaphragm change. It was perfect after 13 years. I would not be concerned for the diaphragm given the small lift necessary to swap the front engine mounts. 



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Hanse 400e "Grey Goose" Hull #31


Posted By: Angelina
Date Posted: 14 August 2019 at 08:29
Hello All!
Thanks very much for the quick replies on an old thread.
I have now now replaced my broken forward mounts with
original yanmar spare parts. Same as the old ones.
As the posters above I have bridged the gap on the threaded bolt with the large nut supplied with the spare part. Now no more freestanding threaded bolt. The height of the installation has stayed very much the same. Yanmar drawings specify 100 - 110 mm between
Bottom of the vibration mount and bottom of the engine bracket. I now have 105 mm.
I did this on a swing mooring in calm seas but 35 degrees and very high humidity.
Both aft cabin doors dismantled, stairway
and lower front engine compartment panel behind stairs
removed.
The engine was liftet by a helping hand with a square
wood of about 90cm as lever. This was wedged between the Grp engine support in front of the engine and the edge
of the oil pan. This is about 1.5cm wide and the wood eventually pushed up on the bolts behind this edge holding the oil pan in place.
I was able to lift the engine just high enough to slide out the old mounts and in the new vibration mounts
with a little bit of jiggling.
Parts are of exactly the same messurement, fitted well.
Thinking and planning was the most difficult.
Just a screwdriver, 12, 13, 17 and 24mm spanner needed.
All done easily in a day.
Just a description of 'My Way'. Not intended as an instruction.
Thanks and be safe out there.
G.
Sorry could not upload pictures due size of file.
Pm if needed.


Posted By: Captain Cook
Date Posted: 16 August 2019 at 22:17
On Marco's wesailhanse page you can find a manual for Yanmar SD 20-50

Try to read page 49: Every 2000 motor-hours, replace engine mounts, and cone clutch!
Or at page 48: Replace rubber diaphragm seal ring every 2 years!

Every year inspect and/or replace flexible engine mounts.
Clearance between the metal parts of the mount bonded to the rubber minimum 1 mm.

This and much more is found at wesailhanse.se




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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: Angelina
Date Posted: 27 August 2019 at 12:59
Hi All,
as reported I recently changed the old vibration mounts.
I bridged the gap on the threaded bolts with the larger nut of the old mounts.
In hindsight I would now probably rather space the whole gap with a piece of stainless steel pipe instead of a nut under the engine bracket.

Anyway, a new question:
Running the engine hard for 2 x 2 hrs trips I noticed
the engine gets very hot. Top of the engine is fine,
Water exchanger etc. can be touched by hand.
However: lower part gets very hot.
Actually the engine brackets get very hot and actually transmit this heat into the vibration mounts!
About as hot as the oil filter gets.
I think the cooling system is fine. Full water flow, exhaust water warm but not too hot. Heat exchanger dismantled and cleaned earlier this year.
Yes an engine gets hot.
And mine runs in 27 degree seawater.
But the engine mounts too hot to touch?

By the way, I have the original blower working.
Pushes out warm air in aft cockpit. However, sounds stupid, but I am unable without dismantling the hose to work out if it blows air out or sucks in??

Anyone get the same hot mounts?

Thanks
G.


Posted By: Sportswagoneer
Date Posted: 08 March 2024 at 19:22
I did a little research into this and found the blog-post from Ellebogen below.

It appears that in saildrive boats, the forward thrust from the propeller is transferred to the hull via the engine mounts. This means that they have to absorb highly fluctuating loads both in the vertical and horizontal plane. (Gravity and thrust.)
(Some prop-shaft boats have a thrust bearing that takes up the thrust load - but that’ll typically be higher power engines.)

Ellebogen specifies a maximum of 7mm spacing between the nuts to avoid damage to the bolts from fatigue.

https://ellebogen.com/en/marine-engine-mounts-levelling-recomendations/" rel="nofollow - https://ellebogen.com/en/marine-engine-mounts-levelling-recomendations/


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2010 Hanse 400 #700 “Neste Sommer”


Posted By: Captain Cook
Date Posted: 08 March 2024 at 22:08
The link above may be interesting for quite a few Hanse owners, who can see more than 7 mm of thread in the engine mounts. Maybe now is the time to buy a couple of nuts and stiffen the bolt a bit? In a worst case scenario, two broken engine mounts may be dangerous when sailing in rough weather. When my mounts broke apart, I had not yet mounted the steel wire in the photo, so the engine danced a kind of rhumba in the engine room until I got it secured. ...................Just a friendly advice.
:Kjeld






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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: Mark_J1
Date Posted: 09 March 2024 at 09:39
Re adding restraint links. I upgraded to R&D Marine mounts with built in ‘rollover’ protection that don’t need the restraint cables but if you don’t have that feature in the mounts they are a great idea.  Our front mounts failed with almost no indication in gentle seas but could have been a much greater problem. The Ellebogen mounts are another good choice. Both are better/cheaper than the Yanmar equivalent. 

Having corresponded with Ellebogen on the failure mode I should to be fair, point out the issue with the Yanmar mounts cyclic failure is at least partly due to poor install practice by Hanse. They had just set the engine too high on the studs. Yanmar even make it clear what the max height is in the install manual. So we had a failure at <400hrs. 600hrs later the R&D Marine mounts are still good (& give less vibration). 

Mark


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Hanse 400e "Grey Goose" Hull #31


Posted By: Captain Cook
Date Posted: 09 March 2024 at 09:47
If you are in doubt if broken engine mounts could sink your boat, read this link:

https://www.sailnet.com/threads/need-help-yanmar-engine-mount.25659/" rel="nofollow - https://www.sailnet.com/threads/need-help-yanmar-engine-mount.25659/

A cat sailor is telling this: "..... the two mounts of both engines broke at exact same place on the studs, leading to a broken and severely leaking saildrive double seal on SB engine due to twisting”

:Kjeld



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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: Sportswagoneer
Date Posted: 09 March 2024 at 10:14
Thanks for contributing your experience!

I have seen a few YouTube videos of engine mount replacements now - and it really looks fairly straight forward. 

An alternative to suspending the engine from a halyard would be to support it from below with wooden blocks or even a standard car jack. Any comments on that?

Also - all the videos are from boats with straight propeller shafts rather than sail drives. As I understand it, sail drives should be quite a lot easier since we don’t need to disconnect the transmission coupling and thus there’s no alignment. 
BUT: There must be SOME alignment? How do you know that the engine is properly elevated/aligned?
You can copy the height from the old mounts - but if Hanse mounted them too high, maybe they should be adjusted?

Also: What about the rear mount at the sail drive? (3JH5e + SD50) Can’t find a video of that and it seems different from the others. Anyone replaced that and have comments on accessibility in a H400 and on alignment and replacement procedure?


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2010 Hanse 400 #700 “Neste Sommer”


Posted By: H8jer
Date Posted: 09 March 2024 at 14:35
Arrrh
Another item to the to-do list!

Just went to my Hanse 370 with a 3YM30 engine.
I have always wondered why my saildrive appeared to point more downward then other boats with same engine...






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Hanse 370#487 30HP 3-cabin


Posted By: landlocked
Date Posted: 09 March 2024 at 16:12
Yanmar may be able to provide the spec for the proper mounting height on your 370.   The height you show in the photo is similar to my 400 and this was the height specified by Yanmar.    They use this threaded stud as a means for adjusting the mounting height which unfortunately leads to stress fractures forming in the thread leading to a failure of the mount.  In other words, it’s “supposed to be” secured at a specified height, not directly on top of the mount so you might want to check first if you are thinking of moving it.   Once you’re sure of the proper height you may want to make a modification as I and others have shown on this site, to prevent the threaded rod from failing.   I think that instead of using a nut to support the engine on the threaded rod, Yanmar should offer some standoffs that can be slipped over the rod after cutting to the specified height, then the rod is only clamping the engine onto the stand-off and not subjected to the torsional stresses.
I have found Yanmar service to be fairly responsive and they’ve been helpful with other issues but when it comes to this common failure mode for the mounts they do not admit to any flaw in the design, and just told me “our mounts don’t break”, so unfortunately they are doing nothing to protect their customers.


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"Kerkyra" 400e #042


Posted By: Captain Cook
Date Posted: 09 March 2024 at 16:57
In a photo on page one of this subject, you can see a Yanmar technical drawing of an engine mount in the background. From this I deduct, that there is supposed to be 8-10 mm of visible thread above the upper nut. Also the danish Yanmar agent mentioned that this was the correct placement on the mount.
Anyway, twelve years ago I lowered the front of the engine with those 8-10 mm, and the engine mounts I fitted then are still going strong. The mounts fitted by Hanse Werft lasted only half that time (by Landlocked only 3 years).
The difference between Landlocked´s solution and mine, are those 8-10 mm, and the fact, that Landlocked´s lower nut is larger than the thread. The nuts on my engine mount are soaked in Locktite, and tightened to the thread.
Obviously I like my own handiwork best, but I suggest, that all Hanse-owners choose to strenghten the bolts on the engine mounts, by adding a few extra nuts, using Landlocked´s method or mine.
Fitting a piece of wire with wire-clamps (photos page 1+3+4) may also be a good idea.
:Kjeld
(I imagine that you took your time to read all the pages of this subject?)


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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: sgrhma2
Date Posted: 09 March 2024 at 19:03
Kjeld is absolutely correct, the lower the engine is mounted down the stud the less the bending moment on it and as such there will be an increase in cycles before fatigue failure for a given stud cross sectional area. All the lower nut does is set the height the engine sits at. Unlike a boat with a shaft drive, a boat that has a saildrive does not need alignment, it only needs mounting in a way that doesn’t stress its diaphragm. If you look at the full range of locational positions that are available in the engine mounts, at none of them is the diaphragm in any danger of being stressed, with plenty of flex still in it available to accommodate extreme movement within the engine mounts. Using additional lower nuts or an oversize one below do nothing for strength, but crucial they act as height shims and increase the effective csa of the stud. If you wanted to you could completely do away entirely with the lower nut and use a series of shims (1, 3, 6, 10mm steel) to set the chosen height of the engine and tighten down the top nut. If you want to go down this route and make your own shims, I would make them square based on the width dimension of the top of the mount and drill the hole 0.5 - 1.0mm larger than the stud diameter. The reason why the mounts will resist stud failure when shims are used is because the bending moment is over a larger csa and similarly the increased area of the shim will eliminate any flexing in the stud itself which causes fatigue cycles. No matter what you do, as Kjeld has done, fitting a wire as back up is an extremely good thing to do.

For those of you that have had failures, it would be very interesting to know what the engine hours were when failure occurred. I would expect that boats fitted with the 40hp engine all have lower hours that failures with ones fitted with a 30hp. The higher mass of the 40hp engine creating higher load fatigue cycles, hence lower potential hours before failure. This doesn’t mean you’re off the hook if you have a 30hp, just slightly longer before fatigue catches up with them. For me what it means is I’m going to check my mounts again and probably make a set of shims.

As to why Yanmar make the mounts the way they do, is simply a case of one set of mounts will work with a saildrive and have the necessary fine adjustment required for shaft alignment. What they provide is a lot cheaper than supplying shims to cover all necessary instalment heights. A simple fix for them would be to use a larger diameter stud, increasing is csa and resistance to fatigue.

Hope this is useful 
Simon


Posted By: landlocked
Date Posted: 09 March 2024 at 20:11
The key is to avoid dynamic loading of the threaded rod, because the stress is greatly amplified in the thread root (compared to solid rod).   So you need something to stabilize the rod from bending and transfer the torsional forces to the rubber mount.   Threaded rods are not supposed to be used for holding dynamic loads because of this stress concentration in the root which leads to fatigue failure.  Ideally you want only tension on the rods.

-------------
"Kerkyra" 400e #042


Posted By: sgrhma2
Date Posted: 09 March 2024 at 20:15
Landlocked, you are absolutely correct, and is indeed why shims work with the standard mount.

Simon 


Posted By: Captain Cook
Date Posted: 10 March 2024 at 10:46
Here are links to the Yanmar official method of placing the engine brackets in the Yanmar engine mount.

https://uploads.tapatalk-cdn.com/files-2540/1581764097_YanmarEngineMounts.pdf" rel="nofollow - https://uploads.tapatalk-cdn.com/files-2540/1581764097_YanmarEngineMounts.pdf

https://www.manualslib.com/manual/1063627/Yanmar-3ym30.html?page=21#manual" rel="nofollow - https://www.manualslib.com/manual/1063627/Yanmar-3ym30.html?page=21#manual

Notice the text: "On all models, try and keep the engine foot or bracket closer to lower end of dimension 'H' if possible." ................. since the difference between the higher and lower end of "H" is 10 mm, I could say, that is exactly what I have done :-) (Lowered the bracket 8-10 mm). In all of my posts I am talking of engines with SAILDRIVE. A fixed propeller shaft needs to be adjusted to 1/10 mm, where the saildrive is more flexible.

My 3JH4E came with the "200" engine mount.

If you check out the homepage of Ellebogen:

https://ellebogen.com/us/yanmar-engine-mount-replacement-marine-engine-yanmar-2gm20/" rel="nofollow - https://ellebogen.com/us/yanmar-engine-mount-replacement-marine-engine-yanmar-2gm20/                     ( update: Just noticed that they sell a set of 3 mounts for my boat)
You will notice, that Ellebogen have stacked the nuts just like I have.
If one has to follow the instructions from Yanmar, the mantra from Ellebogen about max. 7 mm of thread visible may not be possible. I believe, that NO thread at all should be visible under the bracket, and Ellebogen also shows this with stacked nuts.

This discussion (just like the subject of smouldering seacocks) is a matter of some importance, because in the worst case scenario the rubber diaphragm could be torn out of the boat, and then a liferaft would be nice to have.
So, Fellow myhansers, just like H8jer is planning, buy 4 nuts (M16x1,5), a tube of Locktite, a piece of steel wire and four wire clamps. In this case the added security costs less than a semi-bad bottle of Lalande de Pomerol.
:Kjeld
 


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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: H8jer
Date Posted: 10 March 2024 at 11:40
Hi Kjeld

I am getting a quote for new engine-mounts because my engine just passed 1000h and are perhaps 14 years old.
I think my engine mounts looks fatigued compared to your mounts. The height above the rubber looks to be less than yours.
Last season we also had an experience where we had to lower the engine rpm due to excessive vibration. It felt like seaweed in the propeller but going a bit in reverse didn't fix the issue. Afterwards the propeller was inspected an it had no growth or any issues. 
Perhaps the engine starts shaking and the mounts metal parts touch and the rubber can no longer smoothen out the vibrations.

So I will get new mounts and also add nuts so no threads are visible.


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Hanse 370#487 30HP 3-cabin


Posted By: Captain Cook
Date Posted: 10 March 2024 at 19:12
Hi H8jer......Hold your horses...the photo just above your post is 12 years old, when the mount was brand new. Look at page 3, there is a photo where the mount has a little wear.
When you get a quote for a set of three  new mounts, remember to check Ellebogens price. I believe that two mounts in "200" strenght cost €140 + VAT. When I bought two original Yanmar mounts twelve years ago I paid €680 incl. 19% VAT.

I searched my PC for the maintanence procedure for the engine mounts...but no luck. (wesailhanse.se?)
Take a look here:  https://ellebogen.com/us/how-to-detect-when-marine-engine-mounts-need-to-be-replaced/" rel="nofollow - https://ellebogen.com/us/how-to-detect-when-marine-engine-mounts-need-to-be-replaced/
:Kjeld

UPDATE: A quick ”Advanced search/All forums/Any Date/Engine mounts” gave this result:

https://www.myhanse.com/engine-mounts_topic6573_page1.html?KW=engine+mounts" rel="nofollow - https://www.myhanse.com/engine-mounts_topic6573_page1.html?KW=engine+mounts

https://www.myhanse.com/servicing-yanmar-3ym30_topic8760_post70743.html?KW=engine+mounts#70743" rel="nofollow - https://www.myhanse.com/servicing-yanmar-3ym30_topic8760_post70743.html?KW=engine+mounts#70743

https://www.myhanse.com/engine-support_topic8628_post70226.html?KW=engine+mounts#70226" rel="nofollow - https://www.myhanse.com/engine-support_topic8628_post70226.html?KW=engine+mounts#70226

https://www.myhanse.com/engine-mounts_topic9361_post77241.html?KW=engine+mounts#77241" rel="nofollow - https://www.myhanse.com/engine-mounts_topic9361_post77241.html?KW=engine+mounts#77241

https://www.myhanse.com/yanmar-3jh4-engine-service_topic11435_post94564.html?KW=engine+mounts#94564" rel="nofollow - https://www.myhanse.com/yanmar-3jh4-engine-service_topic11435_post94564.html?KW=engine+mounts#94564

https://www.myhanse.com/engine-mount-yanmar-3jh4e_topic14191_post117587.html?KW=engine+mounts#117587" rel="nofollow - https://www.myhanse.com/engine-mount-yanmar-3jh4e_topic14191_post117587.html?KW=engine+mounts#117587

https://sbo.sailboatowners.com/downloads/sailboat__55556031.pdf

The blue water securing of engine mounts is mentioned here:

https://uploads.tapatalk-cdn.com/files-2540/1581764097_YanmarEngineMounts.pdf" rel="nofollow - Offshore safety tie

The mount on the left is the type used under 2GM to 4LH series engines, if you need to pass a Cat 4 inspection for off-shore, put a wire or small chain through the centre 'nose' and over the top of the top metal piece and 'Talurite', crimp or u-bolt the ends together. I have never seen this mount fail because the bonding failed from reasonable use. The failures were always incorrect installation, age, or they became covered in diesel


In the photos of my securing wire (see page 3+4), you´ll see that I have included the bracket in the loop of the wire. This drawing shows a method which does not help against a broken stud.





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Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: DJgun
Date Posted: 24 March 2024 at 13:02
Dear 400 owners.

A lot of mention is made about setting the amount of thread sticking out the top etc, which I believe is ignoring the fundamentals of engine installation.
TheYanmar with saildrive is supposed to be installed in a horizontal position both longitudinally and laterally, and that is why there us a range of adjustment (10mm) in the mount.

You can check whether it is horizontal with a spirit level on the heat exchange on the 3JH4E.

When fitting one new mount I found the  height of  mounts was 105mm one side and 103mm on the other, both being within the specified range 100mm to 110mm. 

Having the engine properly levelled is a key requirement, before you start looking at thread stick-outs etc.  If the motor is properly levelled then it should ensure the prop shaft stays on centreline, and parallel with the water surface. If the motor isn't level transversely it will offset the prop.

The points raised by others about stresses on the threaded stud of the mounts is valid, and the solutions to reducing likelihood of failure are ok. But, first step is to make sure the engine itself is installed level.


-------------
DJ Sailor Ordinaire
HIN DE-HANJ0331J708


Posted By: Captain Cook
Date Posted: 24 March 2024 at 22:02

DJgun wrote:

“A lot of mention is made about setting the amount of thread sticking out the top etc, which I believe is ignoring the fundamentals of engine installation.

TheYanmar with saildrive is supposed to be installed in a horizontal position both longitudinally and laterally, and that is why there us a range of adjustment (10mm) in the mount.”

 You are absolutely right, but it is also true, that you should not have more than 7 mm of visible thread on the stud. Ellebogen is in fact suggesting that you lift the engine mount with spacers to avoid too much thread visible. Even Yanmar tells you to place the engine as low as possible on the stud (thereby making less thread visible).

If you have a fixed propeller shaft, do not pay attention to my suggestions in this thread, but if you have a saildrive, you can choose between broken engine mounts or a method to avoid such a fate.

 I may have forgotten all about sine and cosine, but if I calculate the offset in degrees when I lower my engine 10 mm in the front mounts, it should be like 0,723*tan-1(0,01)=0,4142, which tells me that the engine will get a displacement of less than half a degree. This should easily be absorbed by the rubber diaphragm. At least I now have sailed 12 years with this setup with no problems.

 To sum up the suggestions in this thread:

 If you like to use the spirit level, I have no objections. Fine with me if you choose to place the engine to a tenth of a millimeter in the “right” position. But (having read all the posts in this thread) I will suggest that you buy 4-5 nuts, a few washers and a tube of Loctite. Then I hope that you will put nuts and washers on top of each other and eventually have a setup that looks like the photos from Landlocked or me.

 Sail safely out there

:Kjeld





-------------
Freya H400 #27 (2006), 40HP 3JH4E, 2-cabin, 3-blade Flexofold, Aries LiftUp Windvane, Exturn 300, Jefa DD1,Simrad NX40,Icom M603(VHF)+M802(SSB)


Posted By: DJgun
Date Posted: 25 March 2024 at 10:20
Hi Kjeld,


The focus of my post is to point out that focussing on the number of threads visible on the mount is not the only way to make decisions.

Yes your mathematics is a little  rusty. The longitudinal angle is Tan-1 [10/743) =0.77 degrees.  But one  would not normally talk about levels in degrees. The level is determined in mm/m or similar.  10mm out of level is not "fractions of a mm" as you suggest. It is quite course alignment actually.

As this Sub forum is Hanse 400 I assumed all of them are fitted with saildrives. The propellor shaft I referred to is the shaft the propellor is attached to, which is the output shaft if a saildrive.

Measuring with spirit level is done when the boat is on the mooring or in marina with quiet water, the same as you would be normally doing when adding nuts or spacers. I can't imagine you would be making any engine mount adjustments while sailing.

As far as transverse engine levelling, if for some unknown reason the mounts are set at upper limit one side and the motor therefore a long way from transverse level, and minimum on the other, then potentially the propellor shaft could be offset 36mm from centreline which is significant.

It is very easy to set the motor level using even a small basic spirit level. Easy for a relatively untrained person.

While I don't actually care what other owners choose to do with their engine mounts, I felt it worthwhile  to point out a primary requirement. My 400e has been converted to SD60, and so some other adjustments to motor height are already made. With my considerable professional experience with drive assemblies I felt it prudent to verify the installation myself.  Yes, at one stage I was National Technical Manager for ZF, who actually make the saildrives.

Wrong motor levelling also means incorrect oil level as determined with dipstick monitoring. 

Other owners can do their own "engineering" of engine mounts to avoid failures.  Go your hardest, do whatever you want, it is no skin off my nose.

DJ






-------------
DJ Sailor Ordinaire
HIN DE-HANJ0331J708


Posted By: Sportswagoneer
Date Posted: 25 March 2024 at 11:12
Well I for one, would like to thank both of the knowledgeable gentlemen here for contributing to the thread! I searched quite a bit for "saildrive motor mount alignment" etc. and found ZERO referencs to "optimal leveling" with a saildrive. And while accurate leveling with a saildrive maybe less critical than with a shaft, it's obviously not entirely insignificant!

It's equally obvious that a number of Hanse boats - engine leveled or not - have been delivered from the yard mounted so high up on the bare studs that it has led to very real problems with studs shearing off.

I realize that I may have to compromize between these two issues when the time comes to replace my own mounts - but now I can at least make an informed compromize!

So thanks again to the both of you! Thumbs Up


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2010 Hanse 400 #700 “Neste Sommer”



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