My new boat has water in the 3.0 cylinders

Just bought a 2000 Starcraft with 3.0 merc with about 50 hours on it. Ran fine but poor idle. Figured year old gas was problem. Changed gas but still the same. Pulled plugs - water on the back plug. Compression test has all 4 cylinders at 150. Back cylinder sprayed water out plug hole when spinning over, No water in oil. I figure possiblity is cracked block, head or exhaust manifold or head gasket. Any one of those more likely given the symptoms.

Thanks Mal

 

your gonna have to pull the head ,,,,,,,,maybe it is just a gasket,,good luck,longliner

 

check the exhuast manifold fold a crack found this often with 3.0L's