Seized Engine? Solutions?

[JJsays77]

Hello, I bought a boat at an auction without testing it knowing something is probably wrong, and I'm pretty sure there is now that I have a chance to check it out. It has a 2001 DF115 4stroke efi. The motor won't turn over, I think it tries to turn the flywheel but then dies right after. I checked the spark plugs and the lower spark plug needed to be impact drilled out, and seems to have been melted a bit is why. Looking through the spark plug whole its definitely different than the other 3 cylinders. The motor oil is milky. I'm sure it's plain as day to you guys but just want confirmation to what I think it is because I'm not the most experienced yet. I attached some pictures of the spark plugs.

Now, if it is what I'm suspecting, a seized engine, what would need to be checked/replaced?

And what route do you think is best? Just not bother with it and swap with another engine? Can I tackle this myself, as I'm fairly mechanically inclined? Worth having a marine mechanic do it? (yikes)

 

[Scott Danforth]

since you took an impact to the plug, assume you wipped out the threads

the one plug has bits of piston on it from either severe detonation or the motor got hot enough to melt the pistons.

get an estimate for having your power head rebuilt

 

[99yam40]

will need to open it up to see how bad things got,
is cylinder bore beyond repair?
is head gone too?
milky oil could mean head or block is damaged to the point that cooling passages let water into the sealed internal part of motor

,is crank or rods involved along with piston?

maybe a rebuilt or new power head is needed, but you have to find out what caused it and fix that when you repair or replace power head

 

[Downwindtracker2]

Danger Marine, on Y-tube has a series on the rebuild of a 100hp Evinrude. Worth watching, he's entertaining.