What could have happened?

On the other hand, it’s about an X22XE engine that definitely has it behind us, we’re just interested in what could have happened to the machine. Looks like it’s like he sucked in something hard, sand, pebbles, etc. but the cylinder head looks pure, the valves are also without flaws. The owner of the car has remained in Sweden, a Opel workshop there has diagnosed a piston tipper, which we could confirm, otherwise the engine looks like it had z u little, the wrong or no oil in it any more, we just wonder about the impacts on the piston under the millimeter-thick black crust of all 4 pistons. Check out the photos, maybe you can think of something. Greetings Frankhttp://picasaweb.google.de/oldmanmatze/SINTRAX22xE02#