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Old 02-22-2017, 03:29 PM   #1
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How hard is it to change engine mounts?

It's time to change the engine mounts in our old Grand Banks. The engines are Lehman 120's. How hard is that to do? I understand that we will need to align the engines and the shafts when done. I am just trying to figure out whether I want to change them myself or have it done. I can get probably get the alignment close and have someone that knows what they are doing finish.
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Old 02-22-2017, 04:13 PM   #2
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Are the same mounts still available? Life gets interesting when you go to different mounts, different mounting hole centers, and maybe changing bridges. I would start with an estimate and not to exceed price.

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Old 02-22-2017, 04:41 PM   #3
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Depending on how much room you have around the engine, I'd suggest you change them one at a time by unloading the one you are changing, unbolting the mount from the bed, and removing the engine mount bracket from the engine. Loosely reinstall the new mount in the bracket, bolt the bracket back on and torque it, and adjust the mount.
If you try it this way, unbolt the shaft coupler and separate it before you begin, and use a digital caliper to measure the height of the engine mount bracket above the bed for each mount and write it down or take a pic of it. That puts you back pretty close and you can do an alignment, or have someone else do it.
I've done one side on my OA like this, still have to do the other.
Both Bomac and American Diesel have the stock mounts. There have been several mentions here of CushyFloat mounts but I don't remember the #s.
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Old 02-22-2017, 04:41 PM   #4
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We had to raise one of our 135 Lemans 2 inches, to change to a twin disc trans. In doing so, of course we had to align the shafts. One of the biggest challenges, was just lifting the engines. We had heard of horror stories of people jacking under the oil pan, big no,no. We used a cut down 4x4 straddled over our water tanks, with a chain hoist. Some use bottle jacks. Access, to the outboard mounts, can also be a pain in the neck. The alignment, is easy, of course, once we had a system. The ideal gap between the face of the couplings, is .003.
Which is checked 12, 6, 3, 9 o'clock positions on the face of the coupling. The adjustment is done by adjusting the height on each motor mount, a quarter of a turn at a time. For example, raise the left front mount, and hence, the opposite aft, will close in space. My wife devised a system after a few days of too much wine, from the agg factor. She made a pie chart, with 12, 6, 3 and9, and after she and I would adjust one mount, a quarter of a turn, check the flange for any change in .000. Just Remember this is not rocket science. After this drama, we aligned both our engines, whenever the boat, was refloated. Zero vibration, and no need for a damper
You can do this, my wife is a pharmacist, and I am a car guy since a kid.
Feel free to ask away, we have done it many times over the yesrs..
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Old 02-22-2017, 04:48 PM   #5
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Yes, the mounts are available from American Diesel, Bushings, Inc., and PolyFlex. 4" on center and 5/8" stud (I think). I've talked to all three.
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Old 02-22-2017, 04:52 PM   #6
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Quote:
Originally Posted by O C Diver View Post
Are the same mounts still available? Life gets interesting when you go to different mounts, different mounting hole centers, and maybe changing bridges. I would start with an estimate and not to exceed price.

Ted
Just went though that on a FL SP135 and what a pain. The mounting holes were the same on the engine bed but the actual height of the mounts is what caused the grief. A day later and a boat buck they fit. That being said, if it's a straight swap out pretty easy. We used a 4' maple 2"x4" to raise the engine to slide the mount(s) in and out, one at a time. Our engine bed is steel and we were able to get the 2x4 under each engine mount bracket. A lever can lift a lot. We do have a single engine in the room.
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Old 02-22-2017, 04:57 PM   #7
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See if you can rent a porta power with a button ram. Block of wood under the lip of the oil pan to the stringer to lift. Note: I have not done this on a Grand Banks.
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Old 02-22-2017, 09:45 PM   #8
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Thanks for the responses. I think I will give this a try. There is plenty of room to move about in the engine room. And I'll see about renting a button ram.
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