Topic: Crankshaft repair – Antique Outboard Motor Club,Inc

This topic has 8 replies, 6 voices, and was last updated 6 years, 7 months ago by green-thumbs.

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September 12, 2017 at 9:43 pm #8213
green-thumbs
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US Member - 2 Years
A choice between a bent crankshaft and one with some rust/pitted bearing journals has led to
a emery paper and oil in an attempt to salvage a workable crankshaft.
Am I wasting my time? Any suggestions?
I have feelers out for a better crankshaft too.
Crankcase is plain bearing connecting rods are needle bearing…long story we need not get into here…save that those are only option..
Louis
September 12, 2017 at 10:53 pm #64793
Buccaneer
Participant
US Member
People / machine shops used to straighten crankshafts.
Not sure if anyone does anymore or not.

Prepare to be boarded!
September 12, 2017 at 10:58 pm #64795
RICHARD A. WHITE
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Lifetime Member
If you have access to a good welder meaning the person, he can fill in those pits, then take it to a Professional Automotive machine shop. They will have the correct equipment to regrind it back down. I had my Caille Single crank reground, cost $60…well worth it

http://www.richardsoutboardtools.com
classicomctools@gmail.com
September 12, 2017 at 10:58 pm #64796
chris-p
Participant
I have NEVER been able to polish out a crank that had pitted/rusted journals. Within spec anyways to where I was happy with it. If you can see the outlines of the needles, by the time you polish it out, you will be out of spec.

I suppose this all depends on how rare the crank is? If we are talking about a rare crank, attempting a repair may be your only option. If you are talking a 50s OMC Big Twin, don’t waste your time, there are gazillions of them out there to replace it with.
September 13, 2017 at 12:38 am #64799
green-thumbs
Participant
US Member - 2 Years
Thank one and all for your input. Not a rare crankshaft, just don’t have a better one handy.
Will ramp up search for a good to go replacement.
Louis
September 13, 2017 at 9:51 am #64813
billw
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US Member - 2 Years
Just my observations from over the years: Pits in the crank where plain bearings ride are usually not a problem if the crank is simply cleaned up enough to remove any high spots of rust. Pits where needle bearings run can be okay as long as you can’t catch a fingernail in them or if they’re not across more than half the width of the surface. It WILL make for a noisier engine, though.

Getting a machinist to do anything around here can be absurdly expensive. I just had to pay $80 to have two slots put in a shaft for a pair of 3/4" woodruff keys. He is the only guy on Cape Cod that would even DO it.

Long live American manufacturing!
September 13, 2017 at 3:42 pm #64829
fleetwin
Participant
US Member - 2 Years
What engine is this? Can you post some pictures? I guess a lot depends on how much you will be using the engine afterwards as well…
I agree with Bill, plain bearing/bushings are less effected than roller/needle surfaces. I would be hesitant to trust just any machinist to do crank repairs, look for a replacement crank if needed.
September 13, 2017 at 8:57 pm #64840
Buccaneer
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US Member
From the Johnson 3rd Edition manual…..

Attachments:

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September 13, 2017 at 10:00 pm #64845
green-thumbs
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US Member - 2 Years
That looks like a pretty heavy duty holding device.
If that base is a slab of solid metal it might not be very portable
Thanks for the photo and instructions.
Louis
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Crankshaft repair

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