200 Merc 4 stroke water in oil?

[MonteSS]

Buddy bought a Nitro with low hours. He fished a few times and now changed the oil and very milky and foamy. Refilled, ran 15 mins and changed oil and same. I think he did this again too. Mercury oil he is using is getting expensive. I assume he changed the filter each time but not sure. Runs fine. Plugs look normal and none are "steam cleaned" as might be expected with a blown head gasket. I told him a compression test might varify that. Any other way water or something else could be introduced to the crankcase oil? Ty

He did call a Mercury dealer and spoke to a Tech that is looking into it.

[yam911]

Base gasket or head gasket failure would be my first guess.

[mactlman]

Hopefully still under warranty? if not, I would look into extending the warranty before you take it into the dealer and lose that opportunity

[rocketmanjp]

All good advice & suggestions above. My first 300R was leaking engine oil out of the water intakes in the gearcase from getgo. It was determined that the block had porosity in it allowing oil & water to mix. Mercury Racing replaced the entire engine. Just providing another possibility.

[EuropeanAM]

I would be interested to see a picture or two of the engine oil.

Mercury's 10w30 can appear a bit "frothy" if it's drained immediately after being run. I've seen this mistaken for "water".

BEST way to determine is to place the oil in a glass jar, and let it sit for 24-36 hours, while watching to see if water separates.

If there's any appreciable amount of water getting into the engine oil, it will become THICK.

Be sure to provide the Required Info when posting (serial number). Thanks!

[1ranger487vs]

Every 50 hrs.

[MonteSS]

Ty all. Apologies, I will get serial # and I believe he has pics.

[howieranger]

Another easy test for water in the oil is to put several ounces in a metal cup and heat it to see if water boils out of it.

[MonteSS]

Still trying to get serial # and pics.

Would a compression test show a bad head gasket? Just weird that he says fresh oil is "milky" after getting up to temp and draining. I just know auto engines and what that usually means. But without you seeing pics, we are just guessing.

He said boat and motor are 2020. Original owner used it "lightly" up to 2023. Sat unused in 2024 till my buddy bought it a few months ago. Maybe sitting so long built up condensation?

Good idea Howie.

[yam911]

Hopefully still under warranty? if not, I would look into extending the warranty before you take it into the dealer and lose that opportunity

Once the base warranty is over I don't think Mercury Marine will sell an extended service contract.

[mactlman]

Once the base warranty is over I don't think Mercury Marine will sell an extended service contract.

true--i didn't see where he said the age so I was hoping full him