Milky exhaust on a cold startup

[Sailhound]

Hi if the engine hasn't been run in a week or two, I have noticed that the exhaust water will be milky colored and leave slight sheen behind the boat. Any idea why that may happen and is it cause for concern? It clears up in minute, is just on the initial start.
Thx
Alex

[toddster]

Milky = oil/water mix. Usually. If it has been sitting for a week or two, the mixture should have separated. Possibly the bubbling of a water-lift would produce enough mixing action...

Yesterday, mine put out a cup or so of black gobby oil on startup And thereafter left a tiny but discernible sheen on the water. Conditions were dead calm, so the oil spread out in a perfect semi-circle, leaving no doubt as to who pooped it out.

I'm sure that the black oil thing never happened before, but that sort of sheen would only be visible in very calm conditions. This was the first startup with the new exhaust system. It ran for a while last week with an obstructed exhaust.

[Mo]

Most likely there is nothing wrong. The choke is closed to start, throttle may be opened a bit and fuel in going into the top end as it is turning over and attempts to start. To find a sheen on the water is normal after start-up.

The milky look could be a combination of things, however, it's most likely fuel, air, and exhaust water by products sitting in exhaust for the period of time the boat was sitting. A situation where you have a bad plug will cause those conditions as well.

[marthur]

It ran for a while last week with an obstructed exhaust.

When mine had a partially obscured exhaust due to a collapsing hose, it carbon-ed right up. That mix of poorly burned hydrocarbons and exhaust produced some real gunk that got blasted out when I fixed the problem. Yours may have done something similar.

[Sailhound]

Thanks everyone.
Alex