As a new boat owner after many years, I committed a foolish mistake and forgot to open the fresh water valve and ran my universal m18 until the impeller melted. I was coming out of a marina that had a repair shop and after a number of units, and telling me that they had to replace the pump, they certified that the engine was in goodshape. I was far from home port and it took three days to get there, one under motor. When I returned, I found that the pump leaked oil at the gasket and I topped off the oil. I then noticed that they level shot up above the "full line" and drained off the excess. The next day I ran the motor and found the oil level, again, above the full mark and checking the dip stick, the oil was milky. I removed the pump, drained the oil and found it was saturated with water. The pump did not look new, the gasket was the wrong one and I contacted the marina and they overnighted me a new Oberdofer. I installed the new one with a proper gasket, filled the crankcase and found, immediately, that there was oil/water present. I drained it again, refilled it and ran the motor for 15 minutes. The oil level remained constant, so far and I am hoping that this did the trick. If not, I will have to pull the head and possibly replace the head gasket. Has anyone had a similar problem? Does the pump sometimes leak water into the oil system?