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Failed Engine Mounts

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Sportswagoneer View Drop Down
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    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
2010 Hanse 400 #700 “Neste Sommer”
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Post Options Post Options   Thanks (1) Thanks(1)   Quote DJgun Quote  Post ReplyReply Direct Link To This Post 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






Edited by DJgun - 25 March 2024 at 10:47
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Captain Cook Quote  Post ReplyReply Direct Link To This Post 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





Edited by Captain Cook - 25 March 2024 at 07:51
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)
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Post Options Post Options   Thanks (1) Thanks(1)   Quote DJgun Quote  Post ReplyReply Direct Link To This Post 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.


Edited by DJgun - 24 March 2024 at 13:03
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Captain Cook Quote  Post ReplyReply Direct Link To This Post 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?)
: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

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

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

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

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.





Edited by Captain Cook - 22 March 2024 at 23:15
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)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote H8jer Quote  Post ReplyReply Direct Link To This Post 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.
Hanse 370#487 30HP 3-cabin
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Captain Cook Quote  Post ReplyReply Direct Link To This Post 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

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/                    ( 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
 


Edited by Captain Cook - 10 March 2024 at 23:27
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)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sgrhma2 Quote  Post ReplyReply Direct Link To This Post Posted: 09 March 2024 at 20:15
Landlocked, you are absolutely correct, and is indeed why shims work with the standard mount.

Simon 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote landlocked Quote  Post ReplyReply Direct Link To This Post 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.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote sgrhma2 Quote  Post ReplyReply Direct Link To This Post 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
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