The boat is under restoration
and the exhaust
system was poorly designed and caused seawater to back into the exhaust
mainfold and thus into the oil
pan which is how I discovered the problem. Plus the boat has been sitting for about 14 months with no engine running.
I drained the oil sump (mostly water) and rebuilt the exhaust system with a vented loop and new piping plus a new waterlift muffler
There was no water
in the cylinders, so it is probably a corrosion
problem. I now have Blaster and WD-40 soaking in all Cylinders.
Don't be too upset with me for the impact wrench... it's under reduced power at 80 PSI. I did try turning it by hand with a breaker bar but it's stuck solid.