Water in Cylinder

**scmoose** · 06-14-2019, 08:43 AM

Buddy has a Johnson 4 cylinder that started running like shit. Pulled plugs and found water in one of the cylinders. Pulled head and found a piston and head that looked like its been beat to hell. Wandering what may have caused this. I'm guessing previous owner put wrong plug in and it broke off when piston came into contact with the longer plug. Hoping water is coming from a messed up head gasket but after seeing the piston and head I'm wondering if the cylinder is cracked. He ran the motor for probably six months before he noticed water in the cylinder.

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**scmoose** · 06-14-2019, 08:46 AM

Wish we would have taken a picture of the piston head but the edges are beat to piss corresponding with where you see all the damage on the head. Pulled a small chunk of metal that was embedded into the aluminum head.

**Gone South** · 06-14-2019, 08:49 AM

It can happen from multiple reasons. This one ran lean and got hot around the exhaust port and the ring let go. If the piston doesn’t have marks then someone half ass rebuilt it and reused the head. You could have a blown head gasket, pin hole in the exhaust divider, multiple possibilities.

**ecu1984** · 06-14-2019, 08:53 AM

it's trashed
Could be from several different things, ring could've broken, connecting rod failure, head gasket,
corrosion ate thru the water jacket or it just didn't get any oil.
Is it premix (carb could have plugged up) or is it oil injected (oil pump failure)
Hard to tell

**scmoose** · 06-14-2019, 08:57 AM

Didnt think about a ring breaking and getting in. Curious about the water though. It would either have had to come past the head gasket or through water jacket / cylinder wall correct?

**scmoose** · 06-14-2019, 08:58 AM

Dont think its a con rod, the piston still strokes, motor was running before we pulled the head off. Im leading towards piston ring now.

**scmoose** · 06-14-2019, 09:00 AM

Piston is beat up as well. I dont think the head was pulled prior to him buying the boat.

**Gone South** · 06-14-2019, 09:13 AM

You just got to tear into it further to figure out. The head gasket doesn’t look blown out to me

**SouthernWake** · 06-14-2019, 09:32 AM

Those 4cyl OMC are tough engines.
My guess is water jacket leak and damage from the ring but again, just a guess

I have the shop manual if you need anything from it to reference.