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Old 05-24-2023, 02:10 PM   #1
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Lehman front mount bracket replacement

I'm trying to find the easiest way to replace this bracket. One ear on my port Lehman 80 alternator platform is broken. American Diesel sold me a new casting. I have it painted up and ready to install. What's the best way to take the weight off the engine while I change out the bracket? And can I do this without realigning the engine to the drive shaft?

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Thanks!
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Old 05-24-2023, 03:30 PM   #2
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Not sure exactly how I would lift the engine, it depends on your individual setup. But I would absolutely do an alignment after.
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Old 05-24-2023, 03:53 PM   #3
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I would check the alignment after the part swap but I’d wait a day or so if you have time for the motor mount to resettle. Chances are you’ll be ok but the new part may not be positioned on the mount exactly the same way as it was with the last part. Alignment is easy and you’ll sleep better.

Edit: As far as lifting the engine, I used a 1.5”x3”x2’ on a 6 cylinder Ford Lehman as a lever between the engine and the stringer. Think Archimedes.
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Old 05-24-2023, 06:23 PM   #4
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Buy a mini bottle jack on Amazon. Put a lot of blocking under it.

Take a lot of height measurements on all 4 corners before you start, scribe lines as necessary. Check after finished. You may need to tweak the alignment.
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Old 05-24-2023, 07:08 PM   #5
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3 mounts will support the engine while you loosen the 4th.
Measure the height of the current broken bracket.
Undo the shaft coupling.
Loosen the jam nut on the engine mount then lower the adjustment nut until the mount is not supporting any weight.
Unbolt the bracket from the engine and remove. You may be able to get it off the mount without unbolting the the mount to the original height.
Check shaft alignment.
You can replace engine mounts one at a time, no hoisting, prying or jacking necessary.
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Old 05-24-2023, 07:23 PM   #6
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You can probably loosen the offending mount enough to get it out. Good chance you will not affect the alignment but take it for a drive, notice any new vibration?

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Old 05-24-2023, 08:21 PM   #7
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I just stuck a 2x4 under it and the stringer and sat on it. Lifted engine 1-2" and was done. I did all 4 motor mounts that way, and I am around 170#.
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Old 06-02-2023, 09:26 AM   #8
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Yeah, so last Sunday I did change the bracket out. When I unbolted it, it shifted maybe 3/8 inch? I was able to use a 2x4 longwise and a pry bar to lift it ever so slightly while my wife started the bolts. It was NOT easy. We didn't have time for a test drive after completing the swap but we'll do that and see if we have any vibrations.
Luckily I have a 2x4 onboard. Seems like a good 2x4 comes in handy quite often. You can use it to hammer on, pry, brace something, etc. These fancy marinas never have a proper junk pile. LOL
Thanks everyone for your comments.
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Old 06-02-2023, 10:39 AM   #9
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I once changed all four motor mounts on a FL 120 using a short piece of chain and a pole jack to take the weight off each corner in turn. Then I used a feeler gauge to check the alignment at the prop shaft flange.
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Old 06-05-2023, 02:30 PM   #10
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Earlier this year I was guided by Shellee Fountain to have a look at that bracket after telling her I had wrapped a line around the prop that stalled engine. Impossible to know when it broke tho. I used a bottle jack between engine stringer and the manifold. Local welder saved me shipping costs.
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