What are the possibility of water coming out from one of the spark plug hole?

Question

When boat is running smoothly, then sunddenly slow down. When testing the pressure both of the presure from the cylinder is the same level at 150 psi. But at the same time testing, one of the spark wire cause electric shock. Is that normal.

Answer 1

cracked head, blown head gasket, or cracked block......

Answer 2

so I'm assuming that you had the wires pulled and plugs taken out to do a compression test.  If the wire was close to a metal object, the spark may have bridged and that is what you have seen.  As far as water in a cylinder, I am going to guess cracked block.

Answer 3

blown head gasket warped head

Answer 4

If you have water coming out of a spark plug hole you have either a cracked block or a blown head gasket. Don't run the engine until you find out which. I suspect that you will need a trained mechanic to tell you which you have.

Regards,

Dan