Water in Cylinder

[rwwillhunt]

I have a twin 1986 Yahama 115hp engines. The first time I used the boat it started and run fine when leaving dock. I noticed the port engine dropped 1000 rpms during run and would not develop full power. I checked compression upon return home. Port bank usually carried 125 to 130 compression. When I checked it the bottom read 150 and the top cylinder read 110. I pulled both heads and the port cylinders shows water. The head gasket did not show to be leaking but I am going to replace to try and see if this is problem. Question is what other causes would let water in one side. Due to age and use in salt water I figure could be corrision has caused a hole in water system. The cylinders appear to be Ok best I can tell. If it is in the water system is this something can be fixed or not.
Thanks

[boats.net]

Look for holes in head from water jacket. Pull exhaust plate and check inner plate for corrosion holes.