Any idea why my 4 stroke outboard will occasionally smoke and leave oil residue in water when started.This started last fall and did again yesterday can’t see any sign of a leak and motor runs fine but definitely is oil leak of some kind.Can go days without any issue then will do it again normally only lasts few seconds?
Boats & Motors
2019 mercury 60 hp 4 stroke
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My motor is on a jon boat I fish the Wolf River with. Most fishing is within a half mile of my launching spot and more often than not I don’t put the boat up on plane and run at low speeds. The piston rings need that operating temperature to fully expand and seal. Without that happening there is a minute amount of oil that gets by causing the smoke at startup.
I have a 2020 25 hp Mercury four stroke and on occasion it will smoke for a second or two on startup. I have noticed that it usually does that when I start it cold and then run it for a short time not allowing it to come to operating temperature and then starting it again. I’m guessing a small amount of crankcase oil fetes past the rings and into the cylinder and then goes through the combustion cycle creating the smoke as it burns.
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