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Engines and alignment

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Zoom 495 View Drop Down
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Post Options Post Options   Quote Zoom 495 Quote  Post ReplyReply Direct Link To This Post Topic: Engines and alignment
    Posted: 05 Mar 2016 at 6:39am
I am stuck with the Volvo MD2030 (same as Perkins Perama 20 and 30) that Zoom came to me with. I would prefer a Beta 20, but I have searched for a 2nd hand unit to no avail, and the Volvo has low hours so it stays. The  Volvo was very poorly installed by the previous owner and I have removed it to re-install it. The engine beds are in a different plane than the propeller shaft. The MD2030 mounts were spaced up at the front so the gearbox met the angle of the shaft. Upon removal of the engine, it is apparent that the engine beds are at a way flatter angle than the shaft. Did the factory installed engine have a down angle drive on the gearbox output shaft? Do I need to fabricate and laminate in angled spacers (wedges) on top of the present engine beds?
 The stern tube has separated from the aft engine room bulkhead. It is not leaking (yet) but I can move it and see the crack around the concentric bond in the bulkhead. Does anyone have experience with this problem? 
Any help is appreciated and photos of existing installations or links are welcome!!  
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doug View Drop Down
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Post Options Post Options   Quote doug Quote  Post ReplyReply Direct Link To This Post Posted: 05 Mar 2016 at 8:38pm
If you look on the Technical Papers section you will see a piece on fitting a new engine which has some photographs of a Centaflex coupling in use.
It shows a method of lining up the engine using the prop shaft and a short length of bar fixed in the coupling; a steel rule can then be used across the two to measure the vertical and horizontal alignment, as well as judging the relative angles, as you juggle with the engine.   
The main drawback of this approach is the high cost of the coupling. The advantages are that the coupling can take up a certain amount of mis-alignment, and it is pretty quick and easy to use.
Sorry I can't help with the stern tube but I think there is a also a piece on stern gear there, which may be of help.
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George Isted View Drop Down
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Post Options Post Options   Quote George Isted Quote  Post ReplyReply Direct Link To This Post Posted: 06 Mar 2016 at 9:02am
The separation of the bronze stern tube from the hull on the inside is not uncommon and if you don't have any water coming in that means the bonding of the rest of the stern tube should be fine. Engine vibration, particularly if the shaft/engine is miss-aligned, can cause this. I have had to do a small repair in the same area and having thoroughly de-greased, roughened to a good surface and de-greased again it can be rebounded back in place with the resin/fillers if your choice. As you will know, access is not comfortable but it's an easy repair.
George Isted
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Zoom 495 View Drop Down
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Post Options Post Options   Quote Zoom 495 Quote  Post ReplyReply Direct Link To This Post Posted: 06 Mar 2016 at 6:16pm
Thank you George. There is no leak (yet!) and gross miss alignment is surely the cause!! The engine was not even on the same page as the shaft. The engine beds are set on a more horizontal plane than the shaft suggesting the previous engine (original Volvo) had a down angle gear box. I see on the JR spares list there is a set of engine beds available for re-engine. Do you know if these are engineered to make up for this angular difference? Did your Yanmar 2GM sit on the original beds or were they modified?
Thanks George,kris
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Post Options Post Options   Quote George Isted Quote  Post ReplyReply Direct Link To This Post Posted: 06 Mar 2016 at 8:35pm
I have a 2GM20 that replaced the original Petter-twin.   The original engine beds are still in place but they have been modified with large steel brackets to accept the Yanmar engine mounts. I can't really comment on the Volvo as I have no experience. All the mods do on my boat is bring the engine beds in toward the centre of the boat rather than alter the height.

Hopefully Robin (St Paddy) will see this post and comment as he knows his onions on engines and Co32's.
George Isted
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Keny View Drop Down
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Post Options Post Options   Quote Keny Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2016 at 2:04pm
Hello kris
I had exactly the same problem aligning my own engine.
Eventually I found it much easier to make a new set of engine brackets which fitted the existing beds 
and also aligned the engine correctly.
keny
p.s. there is a picture of one of them in technical papers - 'cure engine vibration'
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Zoom 495 View Drop Down
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Post Options Post Options   Quote Zoom 495 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2016 at 3:54pm
Thanks Keny.
I had a couple large chunks of teak laying about waiting for a purpose and I ripped them on an angle and will fit them to the existing beds to re-align. It won`t be as pretty as your installation looks to be from the photos, but neither are we as refined out here in the Colony of Vancouver Island...
Did you make your own set up for this or did your purchase the kit from JR?
My engine will end up being further forward than it was. I may have room to install a flexible drive  as well.
Are you happy with the Centaflex?
Thank you,kris
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Keny View Drop Down
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Post Options Post Options   Quote Keny Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2016 at 5:09pm
I'm sure you're going about it in the right way. Making the brackets was relatively easy. Measuring up and making some drawings took time. 
Also I stepped the beds as can be seen in the picture. This had no effect on vibration.
The Centaflex works well and is very popular.
Good luck
keny


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Post Options Post Options   Quote Zoom 495 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2016 at 4:44pm
Does anybody know where the technical papers have gone to on the new website?
I can`t seem to find the drawing of the stern gear arrangement.
Thanks,kris
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George Isted View Drop Down
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Post Options Post Options   Quote George Isted Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2016 at 4:50pm
Hi Kris,
The Technical papers are on the class association website but are only available to member of the association. Once you log in you will be able to find them under the resources menu.

This was also the case on the previous website but they were temporarily made available to all on the new one (now fixed).

Best wishes

Edited by George Isted - 09 Mar 2016 at 4:52pm
George Isted
Contessa 32 "Concerto"
Co32 Class Captain and Measurer.
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