1958 Evinrude Bigtwin 35 Excessive oil drainage

[Trackbolt]

I have been noticing that my motor is increasingly discharging unburned two cycle oil from the crankcase into the leg and lt discharges through the water intake bypass at the long plate with holes above the cavitation plate. It is now also draining from the small hole/vent above the gear case. Is this a crankcase seal issue? I have never seen this much drainage an any drainage for that matter. We've owned it since it was new. I am sure it is two cycle oil as it is a milky blue color after mixing with water. The blue tint and smell of raw two cy I use 32 oz two cycle outboard motor oil to each six gallons of gas. That is what is specified. I know excessive oil from the crankdase drains down and is discharged while the boat is under way. I don't think it is a seal as the motor still creates good vacuum. Compression is 120/120 and the plugs look normal. Carbs are dialed in for good idle and smooth cruising at 3/4 throttle. I rebuilt the ignition with new points, condenser, coils and plug wires and syncronized the throttle to the mag timing. What am I witnessing?

 

[HighTrim]

I would normally reply that being a 2 stroke, it is normal to see some unburnt fuel/oil mix being discharged with the spent cooling water, but since you have owned this for a number of years, you can obviously tell that it is excessive. That being said. Are both cylinders firing with good spark? Have you noticed any performance differences? What about the gear oil? Have the lower unit seals been leaking? Check the gear oil for water.

 

[boobie]

Is the motor coming up to temperature especially at idle ??

 

[Trackbolt]

I recently replaced the lower unit seals. I last replaced them about 1985. The lower unit oil was getting milky. When I had the lower unit off there was unburned 2 cycle oil all over the water pump housing and in the lower unit above the gear case, Thats when I began to think this was out of the ordinary as I an mot used to seeing this oil there. Since the recent re seal the lower unit has not had any water intrusion. I drained and replaced the oil after a few hours of running and the oil was clean. The excessive engine oil problem began earlier this year after I put the motor back in service from a 15 year storage. I rebuilt the carb and replaced the coils, plug wires, points, condenser and spark plugs. Compression is 120/120. I adjusted the carb as follows. Low speed knob 1 1;2 turns out from seated and high speed 3/4 out. Adjusted low speed to best idle. Adjusted high speed knob underway at WOT to smoothest operation. Returned to idle and re adjusted low sligntly leaner to best idle. Underway at WOT checked high speed and it checked out smooth at a little leaner. Final set for packing nut lock down is low at 1 3/8 out from stop and high at 9/16 out from stop. Motor idles all day without miss and throttle is smooth and responsive in all positions. That has historically always been my method and results. The motor runs great as it always has. I am just concerned about something that I am not used to seeing.

Thanks
Tony

 

[Trackbolt]

Motor runs cool. There is no thermostat on this motor. While idling you can rest your hand on the head and leave it there. Discharge water only luke warm.