Ok well about a month ago i had a bad knocking sounds on the fourth cylinder n when i took it all a part it was the rod bearing was all smushed up so i replaced all of them might as well since i had them out but then when i went to go drive it for about 10 min my car had problems turing back on n had to tow it hom just now i checked the bearing again it was all smushed up again? could it be the crank?