So at the end of last season, after experiencing some hydrolocking during start-up of our Alpha 5.7L Magnum in our 1987 Sea Ray Pachanga 22 and then some knocking we took it out of the water. Did a compression test and found cylinders 1,3,5&7 all below 50psi and 2,4,6&8 all above 145psi. Rather than digging into then we had the motor winterized and we just pulled the motor out last weekend. Upon investigation, the exhaust gasket between the log and the elbow had a small leak that was allowing water to enter the cylinder that had the exhaust valve open and that would be the cylinder that would buck back against the starter. This condition broke the tops of the pistons on that side of the motor (1,3,5,7). Cylinder walls look good, the heads look good, but the tops of those pistons were broken so we dug some more to check the bearings. All of the bearings and rods look good but some of the piston skirts were broken off. In fact 5 of the pistons had broken skirts! Even one of the pistons that didn't have a broken top and wasn't from the side that had the water leak... I understand why the skirts would break off of the ones that had broken tops, but why the random one (I can't remember which cylinder it was from)? The motor is in my garage and I'll look to see which cylinder it was from, but what would cause that to happen? 100% bone stock engine that has never been cracked open or out of the boat. Boat and motor have 581 hours on them.
