Re: water in oil on 3.0 mercruiser
there's a very good chance that your block is cracked. A water leak into a manifold will not get your oil milky. The piston rings are designed to seal and keep anything from getting past. While some stuff gets past, you would not get enough water past in 2 minutes to cause any milk in the oil. If you got that much water into your cylinders you would hydro-lock. If the boat sat for 2 years in a freezing temperatrue someone probably didn't winterize it properly and that's where your crack is from. The reason that a crack can cause over heating is your thermostat is suppose to maintain pressure on the cooling system. When you lose pressure, you also lose the ability to cool. The water turns to steam and steam does not absorb heat well. The pressure that is suppose to be in the system prevents that from happening. Take off the side lifter cover and look for a crack there. That's usually where it will crack, but it could crack in other places. Look down into the cylinders with a boroscope (if you can get one) and look for any heavy discoloration. The head gasket is probably fine. If you only ran it for 2 minutes, the gasket couldn't let much water past. If there's water in your oil the impeller is working. You didn't over heat it. 200 is stil okay. Once you get to about 220 is when the problems start.
Now that there's water in the oil, you might end up with some bad bearings, but you might be lucky and they'll be okay. Definitely change the oil filter once you fix the leak and i would run some trans fluid through the system before you start it up. To do that, take your distrubutor out (make sure to mark it for reinstalling it!!) and get a long flat blade attatchment for an electric or cordless dirll. Fill your oil pan with trans fluid and put a new oil filter on. Then using the drill spin the oil pump drive the same direction the distributor would spin it (mine goes CCW). The trans fluid will clean the system out.
Hope this helps.
P.S.-A leaking manifold is a cause for rusty cylinders, spark plugs, and valves. NOT a cause for water in the oil. Any water in the cylinder would either evaporate, cause the engine to sputter, or hydro-lock the pistons. Depending on how much water gets in. The piston rings seal and don't let much air past, water would have a harder time getting past. Even if water got in the cylinder and sat there, it would still leak very very slowly. I've had coolant sit in a cylinder and not leak past at all.
