Powerhead swaps - Can it be done?

Vintage Iron

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I have a 1955 12 hp Goodyear Sea-Bee that has been sitting in a garage for over 10 years. The motor is seized up – don’t know if it’s pistons welded to the bores or rusted crankshaft journals. The propeller turns freely and rocking the prop back and forth lets me shift F-N-R pretty easily. Would a later model Gale 12hp or 15hp powerhead fit in place of the stock unit? That would sure broaden the search possibilities. In looking at the parts manuals, the exhaust tube gasket and the lower unit flange gasket change from two separate gaskets to a one-piece gasket and baffle. I don’t know if this change was due to design changes or cost-efficiency. I’d sure welcome any ideas y’all have.

Thanks!

Dave
 
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F_R

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Need the model number. There were a "Standard" and a "Deluxe". Not interchangeable between the two.
 

Vintage Iron

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Thanks for the response FR. The model number is 25-3572. I didn't know about the Standard/Deluxe difference. It'll be a hoot to tear into it and see what it's like on the inside. The biggest 'outside' difference is the gas tank that's part of the engine cowling. The owner's manual talks about an optional 'Bosun fuel tank system' that bolts a fuel vacuum-operated pump onto the engine and uses a separate tank to provide fuel. Although it's 10 years older than my 5hp Sea King, the fuel system sure looks the same. I think the biggest difference will be the bearings and bushings - silver/brass/whatever instead of needles.
 

F_R

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That model translates to a Gale model 12D11. The "D" means Deluxe. But now it starts to get complicated. The 1955 Deluxe continued to be made as a 12S-- (Standard) in a few subsequent years, along with the redesigned 12D-- Deluxe models.

You will see significant differences merely by look. The gas tank. The rubber mounts on the newer deluxe models. Different lower units with different number of bolts holding it on. Little things like that.

The 12's all had plain bearings. Not till the 15's did they get any needle/roller bearings. But the 15 is similar to the redesigned 12 and won't fit yours.
 

Vintage Iron

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Yup, I was wondering about the different base gaskets between the lower unit and the powerhead. It sounds like I need to stay with an older 12hp. The idea of upgrading to a 15hp with better bearings sure was attractive. I saw a picture of a 1958 12hp and the lower gasket was one piece. That sorta narrows down the years that'll work as ggod substitutes. Thanks for clearing up the confusion. It definitely helps me focus on what to look for.
 

tomhath

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I have a 1955 12 hp Goodyear Sea-Bee that has been sitting in a garage for over 10 years. The motor is seized up – don’t know if it’s pistons welded to the bores or rusted crankshaft journals.
Dave

First thing to try is to lay the motor down with the spark plugs removed and pour automatic transmission fluid into the cylinders. Let it soak for a few days and try turning the crank occasionally. Often that's enough to free up stuck rings, many motors have been brought back to life with that treatment.
 

Vintage Iron

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Good idea. I use Marvel Mystery Oil ? good stuff and it really works its way through tight spots. My big worry is rust on the crankshaft journals. I don?t want to ruin the thin silver-plate bearing surfaces on the rod big ends. I?ll let the MMO work for a week, then I?ll split the crankcase. The rod bolts come in through the bottom of the rod, so with the crankcase removed, I can loosen them and remove the rod caps and crankshaft. Then when I work the cylinders free, there?ll be no worries about turning the crankshaft and scoring one of the rod bearing surfaces.

That?s the plan?..
 

F_R

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And a good plan, for the good reasons you state.
 
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