Rusted/Seized Yamaha 15SK

[Eagle14]

Howdy,

I was given a 1984 15HP Yamaha. Model 15SK. I went through the normal assessments for a sleeping outboard. Motor is in fine shape in general. Will need new impeller, carb kit, flush/refill lower.

But, major problem. Motor is seized. I've disassembled the motor and removed the engine. The head is removed and the bottom end is exposed revealing surface rust on most visible internal parts. Main bearings, rods, piston skirts, cylider walls, etc.

I have beat on the pistons somewhat and likewise from the bottom end with no result. It is currently saturated in penetrating oil, and the beatings will continue.

If I can free it up, I'm pretty sure I will scrap it.

In its current state, what are some of your ideas for recovering this motor? It is literally "like new" with the obvious exceptions...

Thanks for your input...

JR

 

[RogersJetboat454]

Re: Rusted/Seized Yamaha 15SK

Pictures would help with better answers...
But if it's as crusty inside as you say (as in the bearings and crank are shot), the cheapest/easiest thing to do would be to find a powerhead in good shape and go from there.

 

[Capt Ken]

Re: Rusted/Seized Yamaha 15SK

Tie a long string to it with a plastic clorex bottle on the other end. Use it to mark a fishing spot.

 

[Eagle14]

Re: Rusted/Seized Yamaha 15SK

I got the pistons free of the block. The cylinders look pretty good. Hone marks are still visible where there isn't surface rust. I will run a hone through them to see if there is any deep corrosion on the sleeves.

The crank/piston assembly looks fair. Main bearings move but would need to be replaced. The rod bearings are smooth as well as the wristpin bearings. I managed to crack one of the skirts on a piston in the process.

It seems I'm looking at a new crank/piston assembly. I will look around to see what parts are out there.