I have purchased a boat that has a 55hp Johnson on it. I have the motor running great but I have one problem. The motor has been setting for about 6 years. It was rebuilt before it was stored and is in relativly good shape. I have replaced the wiring harness, thermostat, plugs and rebuilt the carbs. Now when it runs I get oil mixture coming from the crankcase vent below the carbs that has a tube running back to the air intake cover. What causes this? Could it be caused by the engine overheating and the gas evaporating before it is burnt. I had a problem with trash in the cooling system but I have flushed it now. The amount of oil was about couple of tablespoons if the engine runs about 15 minutes. 