Mounting diesel motor

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Tallystick
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Mounting diesel motor

Post by Tallystick »

The motor mounts on the diesel going into my boat are a little off from the stock A4 mounts. The flywheel mount needs to move lower and to port slightly and the front mount will likely need to be adjusted up or down. What are recommended methods for accomplishing this? I was thinking of extending the existing mount with white oak epoxied, screwed in, and glassed over. I would then shim with white oak waterproofed using epoxy.

How could I improve on this plan?
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Rachel
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Re: Mounting diesel motor

Post by Rachel »

Could you post a few photos of your existing engine beds? It would be nice to see how they are constructed, what they're made of, the geometry, etc.
bcooke
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Re: Mounting diesel motor

Post by bcooke »

Most of the original engine mounts in Tritons that I have seen are pretty crappy. I wouldn't tack anything to them. I would knock out what you have and start with a new bed designed for your new engine.
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Tallystick
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Re: Mounting diesel motor

Post by Tallystick »

Well it looks like I will be able to use the original motor mounts if I shorten the prop shaft slightly. They seem sufficiently solid that I'm not confident that bedding new ones would be an improvement over using the existing mounts with possibly some reinforcement. The existing metal plates that go over the fiberglass mounts could maybe be reused if I chop off the side pieces that protrude towards the motor. Some fiberglass tabbing on the interior of the mounts to the hull may provide strengthening to complement the tabbing on the outside of the mounts.

The motor is in place just for fitment at this point.

Does this sound reasonable?

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Triton106
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Re: Mounting diesel motor

Post by Triton106 »

I have thought about this question from time to time whenever diesel envy hits me. In my case, the diesels I have considered are Yanmar 2GM20 or a small Beta (14 or 20 HP). In both cases the diesel engine mounting width (14.5" for the Yanmar) are wider than my existing Atomic 4 mounts (11.5" I am going from memory). Although Beta offers Atomic 4 mounting option I don't like it. So, I know I would have to add to the outside of the existing foundations if I were to reuse them. West coast Triton Atomic 4 foundations are made of oak planks heavily glassed to the hull. So unless they have rot (in my case they did and I have dealt with them) they are pretty strong. Another west coast Triton - Head over hills - did exactly that.

The pictures you posted don't tell me how strong the existing east coast fiberglass mounts are and you need to make that assessment. If in doubt I would redo them as Britton suggested. If you believe they are strong enough then you should be able to modify it. From the pictures you posted it seems that you existing foundations are wider than the diesel mounting width as the diesel mounts in the pictures are only partially sitting on the existing foundations. I don't know how that is possible with Atomic 4 mounting width being only 11.5". But that is not the point here. To modify the foundation I would epoxy oak planks (or other appropriate wood) to the inside of the fiberglass foundations and the hull. I would then epoxy an 1/2 inch G10 on top of the foundation and the new oak planks for the engine mounts to sit on (obviously you need to make sure that the final height of the foundation allows the shaft coupling to be properly aligned.)

This is not a trivial job. So Britton may be right that it may be easier to just start from scratch. Hope this helps.
Ray D. Chang
Triton 106 in Berkeley, CA
Tallystick
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Re: Mounting diesel motor

Post by Tallystick »

Hi Ray, I appreciate the feedback. By the way the motor is a Pisces 27, the marine version of an Isuzu 2AB1, which is the reason for the different geometry. Your suggestions for reinforcing the interior of the existing foundations dovetails with my thinking. I have some nice quartersawn white oak that will be used. The metal plates in the above photos go on top of the glass foundations for the Atomic 4 mounts. The tabs on the metal plates protrude and interfere with the diesel, so I will have to cut away the unneeded portion of the metal plates. Once the plates are bolted back onto the fiberglass, the motor will be resting fully on the metal supports.

One thing I'm not clear on, are you suggesting that it would be preferable to discard the metal plates in favor of oak planks in between the fiberglass foundations and the motor?
Triton106
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Re: Mounting diesel motor

Post by Triton106 »

Sorry for not being clear. The metal plates look pretty rusted in the picture. So in my mind I have discounted them as inappropriate for reuse. That's why I suggest that you use 1/2" G10 plates instead. The G10 plates will sit on top of the both the existing foundation and the oak plank which will also improve the bonding between the two. However, if the metal plates are still sound you can reuse them.
Ray D. Chang
Triton 106 in Berkeley, CA
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