Jun 30, 2012 #one There are a lot of water-in-the-oil threads so I just believed I might toss this on the market. Any water usually means a seal is leaking, and it could be as simple as an oil fill plug seal or as hard being a prop shaft seal. https://kameronxcilp.wikijm.com/1448385/about_mercury_outboard_motor_carburetor