Having no idea what motor we are talking about but I can tell you the number one cause of water intrusion on Johnson/Evinrudes is the little nylon gaskets on the vent and drain plugs. They should be replaced each time you pull the plugs. Beyond that I would suggest posting your question in the appropriate forum at
www.iboats.com . But please, for your own sake provide some detail on the make, model and year or they might jump all over you. Lots of very good marine buffs respond to all questions. Best of luck. Rick.