Mercury 6hp water in oil issue help

[jmurray109]

Disclaimer, I am not a mechanic and watch YouTube videos to try and figure things out.

So I recently received a 2013 Mercury 6hp MFS6CS outboard. It was briefly inspected by a local outboard shop and needed a new lower end. I was able to order a new lower end and I installed it.

Since then, the motor has only been started on a stand with the water flush hose attached. It ran fine without any issues. After several months I again started the motor on the stand. I ran it for several minutes before getting ready to change the oil. The engine stalled out after 2-3 minutes and I checked the oil and discovered it had water inside. I changed the oil and ran it again, for 2-3 minutes and again discovered water inside the oil.

My question is where is the water coming from. My first and only guess was a head gasket issue. After watching a video I removed the head. I did not notice anything that jumped out (see pictures). The gasket appeared in good condition.

So I am confused, and not sure how water is getting into oil. I don’t see any cracks and the spark plug was dry. The top of the cylinder was lightly lubricated, without water. The lifters/push rods had the milky water/oil inside.

Any help would be helpful. I have ordered the new gaskets and plan to put back together unless someone knows another possible cause that I can inspect


.

[tkeithlu]

Hummmm. Two types of possibilities. One is any gasket that lies between the coolant passages and the valves/cylinder/crankcase, not just the head gasket. The other is a crack in a similar location. You are replacing the gaskets. A dye penetrant kit is not cheap, but may be the only way to make sure. Here are some examples:

https://www.amazon.com/dye-penetrant...+penetrant+kit

One area for suspicion is the connection of the new lower foot. That contains both the exhaust and the water, and you recently disturbed it.

[Michal 263]

[QUOTE=jmurray109;3373381]Disclaimer, I am not a mechanic and watch YouTube videos to try and figure things out.

So I recently received a 2013 Mercury 6hp MFS6CS outboard. It was briefly inspected by a local outboard shop and needed a new lower end. I was able to order a new lower end and I installed it.

Since then, the motor has only been started on a stand with the water flush hose attached. It ran fine without any issues. After several months I again started the motor on the stand. I ran it for several minutes before getting ready to change the oil. The engine stalled out after 2-3 minutes and I checked the oil and discovered it had water inside. I changed the oil and ran it again, for 2-3 minutes and again discovered water inside the oil.

My question is where is the water coming from. My first and only guess was a head gasket issue. After watching a video I removed the head. I did not notice anything that jumped out (see pictures). The gasket appeared in good condition.

So I am confused, and not sure how water is getting into oil. I don’t see any cracks and the spark plug was dry. The top of the cylinder was lightly lubricated, without water. The lifters/push rods had the milky water/oil inside.

Any help would be helpful. I have ordered the new gaskets and plan to put back together unless someone knows another possible cause that I can inspect


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]Hey found your post looking for a solution to my engine failure. It looks like I have exactly the same problem. Were you able to solve it and would you share the solution? I will add that I have already replaced the gasket and oil.

[Michal 263]

Hey found your post looking for a solution to my engine failure. It looks like I have exactly the same problem. Were you able to solve it and would you share the solution? I will add that I have already replaced the gasket and oil.

[Rumrace]

Need to run blue ink and a big magnet for iron similar dust for aluminum . Then toss it. If at one point the crank was sloping about you cracked the cylinder jackets. Cast iron is awful cast aluminum sleeved in some cases worse. I’m not a mechanic by trade either but I’ve built a long list of modern and antique motors. I swore off cast iron toss 454’s out with weak cranks and LS3 replacements. I’ve hated 2 strokes since a 500 Kawasaki beat my 883 Harley.