Reply To: Mercury KF-7 lightning – bottom cylinder drops out.

[billw]

I guess if the cylinder was completely non-functional, you’d see some water. Sometimes you have to tap the plug on your oily palm and watch for beads of water. Take the plug out right after running the motor when the problem happened. As for the seal and the hole, good question. Best way is to take it apart and look; but who wants to do that on a whim? What if you just pulled only the power head and sprayed some carb cleaner down the carb, and turned it over a few times to see if residue came out of the crank area? The last seal I saw with a hole, had a tiny hole….like about a #52 drill bit. That was in lieu of any formal crank case drain system.

Now that I re-read your post, it ran for three years okay; so forget about the hole in the seal. what if your lower seal has failed? You’d loose the crank case pressure at lower speeds

Long live American manufacturing!