water in oil in outboard

Andy Grant

Andy Grant

Well-known member
I have a friend that has a fairly new 10 or 15 hp mercury outboard that get water into the oil under heavy load. No, no warrany left.

I first thought is a bad head gasket. Is this is it, are they difficult to change?
 
Andy,

Is this a four stroke or two stroke engine?


As far as changing the head gasket; getting to the head, may require more work than actually changing the gasket. All depends on just what items are in the way and have to be removed. If you don't have a good manual, exploded views are available on-line.
 
One last stupid question.... Is it water for sure? Some 4 strokes "make oil" in that they accumulate gas in the oil.
 
One last stupid question.... Is it water for sure? Some 4 strokes "make oil" in that they accumulate gas in the oil.
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You know I haven't seen it personally. The gas would be a problem too, right?
 
I don't know what models do it, but by "making oil" it means that the oil level goes up and up because gas is getting past the rings into the oil. It was something you heard more about in the older 4 strokes.

It would obviously be easy to tell, is there a layer of water at the bottom of the dirty oil or is it just a larger volume of oil?
 
If there was water in the oil, wouldnt the oil have a grey, gooey, milky appearence?
At least the 78 honda civic I had back in 1987 did when it had an exhaust gasket leak that let water into the block....
 
If there was water in the oil, wouldnt the oil have a grey, gooey, milky appearence?
At least the 78 honda civic I had back in 1987 did when it had an exhaust gasket leak that let water into the block....
Click to expand...


Yes.
 
Some 4-strokes also accumulate moisture from the air and that gets into the oil or under the oil. In the oil is the normal milky brownish stuff, but if the oil pick up does not go to the bottom then water can condense and float the oil up "making oil" on the dip stick.

Right now I can not recall which brand of motor this moisture condensing issue is common in. I was looking at info for my recently acquired 4-stroke Honda when I came across it on Iboats forums. Probably a Honda.
 
The making oil issue on 4 strokes is widely known. If its water in your oil from moisture it can be harder to diagnose.I have 115 4 stroke thats crankcase oil was rising from fuel. The cause was I had a thermostat that was stuck open and the engine wasn't getting up to operating temp which was letting fuel slip by the rings and enter the crankcase oil. Changed the thermostat , problem was gone. Good luck
 
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