Hey everyone, my boat overheated and hydro locked from a bad thermostat. I changed the thermostat took it back out and it is overheating still and water in cylinders, I pulled the plugs while on the lake and if I turn motor over water is pumping out of the spark plug holes like a pump. No water in bottom end of motor, I have pulled the riser and exhaust manifold off the faulty side and the gaskets look ok not great, can a failed gasket literally pump water into cylinders? It’s a lot of water! Motor is a 2005 Volvo penta 5.7gxi -F

 

You don't "hydro lock" from a bad thermostat. Hydro lock occurs when water (or any other liquid) gets into the cylinders and the engine won't spin over because liquid does not compress. That water is coming from somewhere - more than likely a damaged head gasket or a cracked block from freezing one winter. Your positive displacement sea water pump is what is pumping the water into the engine (like it's supposed to)

When a cylinder fills even partly with water and you try to start the engine - the connecting rods can get easily bent. So - on a boat engine I would certainly want to make sure those were ok. Sorry for your troubles.