I have a 17′ 1985 Four Winns ski boat with a 140 HP inboard. When I got the boat the engine wouldn’t turn over. Turned out that water had gotten into one of the cylinders and froze the piston to the cylinder wall. I took the head off and soaked the cylinder with PB blaster for several days. I still can’t get the engine to turn over. Does anyone have any ideas to break it free? Any products that would work?