40HP Merc Water In Cylinders

[Lewis1111]

Hey guys looking for some help on understanding how water could be getting into the cylinders...

40HP Mercury 4 cylinder SN: 0D101043

Some background-engine was not running on the top 2 cylinders, spark is good and compression is good on all cylinders. Pulled the plugs and top 2 are very clean-no water droplets-installed 2 very used dirty plugs in the top two cylinders and ran engine for 5 mins. When removed they were clean. Pulled the exhaust baffle plate and gaskets, it actually looks pretty good no holes or major corrosion (fresh water boat)..leaning towards a cracked block but open to any other suggestions....

 

[racerone]

Perhaps the bottom crank seals are bad.----Does spark jump a gap of 3/8" or more on all leads , yes or no ?-----What are the compression numbers ?----Have you checked fuel pump diaphragm ?

 

[Lewis1111]

Compression is 125 psi on all 4 cylinders. Yes the spark will jump a 3/8 gap. Checked DVA on the trigger/power pack/stator wires as per CDI Electronics as at first I suspected a ignition issue. Have not checked the fuel pump diaphragm. Is it possible it is allowing fuel into the crankcase and that is washing the plugs?

 

[racerone]

Why of course !----That is why I suggested you check that.