Hello, I just bought a Flicka 20 with a yanmar 1gm10 engine that hasn't been maintained for about ten years(boat and engine). She starts though. I had a mechanic friend help me run through the basics. We cleaned out the water lines, changed the oil and found water inside when checking the oil (He didn't think it had water in for too long, only after we cleaned the lines out did it start to leak). Then proceeded to change the water pump which was leaking. After changing the oil a second time the low oil pressure light/buzzer wouldn't shut off. It had not gone off yet, only after the water pump and fresh oil. The oil had been drained the second time through a plug near the bottom of the engine. My friend wanted to do some research, but he is stumped as to why it still has low oil pressure. Any thoughts? Thank you for your consideration.