crank seals

Memorial at the lake boat slow down and running rough with white smoke with bad odor Fouling plugs in only 2 minutes of replacement,,, did it twice! I’m guessing is causing by a bad crankcase seal or inner crank seal leaking oil into cylinders. Any recommendation? Can I pull engine out and do it...

I did a leak test to find that my crank seals leak to the Rotary Valve gear chamber. One or both of the center oil seals on the crank seem to be bad. My problem the ski had, was it wouldn't start in water, and I did EVERYTHING to it to try to remedy the problem. My challenge is for someone...