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Discussion Starter #1
Hello Everyone,

So this old 1975 Grampian 28 we just bought has cracked engine mounts. The engine shakes when it runs and this has been designated as the no. 1 issue to deal with before the boat is put back in the water.

What are those things made of? I'm guessing some kind of heavy hardwood blocks wrapped in fiberglass with polyester resin?

Anyone have any experiance repairing them without taking the engine out? The engine is at the end of its life but still works, so if the mounts are repaired just enough to last for a couple of years till we replace the engine I will be happy.

I can work fiberglass, wood and epoxy, weld steel or stainless. I just don't know which approach to pick since I've never worked on a boat before...

Thanks for any and all feedback...
 

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When I rebuilt my engine, I had no vibration insulators, just bolted down. I changed that and added some I got from Grainger. Grainger Industrial Supply - MRO Supplies, MRO Equipment, Tools & Solutions are rated in weight of load and deflection (side movement). You do not want much movement because of the shaft should not be allowed to move, you will damage to Cutlass bearing. You will need to uncouple the shaft to make sure any mount changes you make does not change the alignment. Proper alignment is critical. Here is a video on how to align...https://www.youtube.com/watch?v=kY0scm6bfdI

You may want to take this opportunity to change and or service the Cutlass and seal.
 

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Discussion Starter #3
I took a look under the engine, and I see what seems to be four vibration isolators. I don't know what condition they are in, but they are there! ;)

I cleaned up the area a bit to see what I'm up against. You can see assorted cracking on both sides of the mounts, and at several points around the cross brace between them.

I sanded a bit and found that under the grime is a layer of paint, under that is a layer of bondo like fairing compound, and under is a fiberglass and probably epoxy patch, and under that is the original engine mount!

I noticed the patching was not very effective. I suspect it is simply far too thin. Seems to be in the 1/16 to 1/8 inch range. It needs to be way more than that to stop an engine from shaking!

I have to buy a sanding tool of some kind to get right in there and remove all the fairing compound, it is not very strong and will prevent any real repair from happening. I'm thinking maybe one of those hand held belt sanders would work. Need to find where I can get one of those in Ontario.
 

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what is shaking is the mount loose in the hull? are the vibration mounts loose on the mounting block. is it just the engine shaking in the vibration mounts. that two lunger is going to shake. it will never be like a car engine. I have seen many people that thought there was a problem with their two cylinder engine, but it was normal for these engines to shake some
 

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Discussion Starter #5
When the engine is at idle and you look down from the companionway, you can see the engine mounts under the flywheel "flopping" from side to side. They lean left and right with engine rotation. The engine mounts also have several substantial cracks where they are fibreglassed to the hull, and all around the crossmembre under the flywheel. These cracks are open enough to slide a screwdriver into and pry up laminations.

It seems to me the engine should be shaking a bit in its mounts, but the engine mounts themselves should not be following it!?
 
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