Oil return line

[Evinrude Boater]

I have the lower engine covers off my 1964 Evinrude 75hp and I think I've found the oil return line that dumps fuel down the exhaust. Am I right?
We discussed this issue in another thread and it was indicated that this line could be cut off and plugged at the left side and the right side routed to a collection receptacle.
Where does this excess fuel come from? Is there any chance of something not being lubricated by rerouting this line?

 

[Chris1956]

Re: Oil return line

My '59 Fat-Fufty V4 had the line, I do not know if the '64 has it. On my Fatty, the line ran from the base of the intake manifold (under the carb) to the starboard sie of the motor, to a brass nipple. It dumps raw fuel into the water directly, so the modification will not starve any part of the motor of lubrication.

I took a 1 pint plastic 2 cycle oil bottle and installed a brass hose barb in the cap. I then cut out 1/2 the bottom of the bottle and "wired" it upside down next to the carb. The cut out bottom was next to the intakes, and a hose coming off the hose barb ran back to the gas tank. Now route the fuel/oil purge line into the bottle, and the fuel drips back into the tank, and the vapors are reburnt.

 

[F_R]

Re: Oil return line

I have the lower engine covers off my 1964 Evinrude 75hp and I think I've found the oil return line that dumps fuel down the exhaust. Am I right?
We discussed this issue in another thread and it was indicated that this line could be cut off and plugged at the left side and the right side routed to a collection receptacle.
Where does this excess fuel come from? Is there any chance of something not being lubricated by rerouting this line?

Yes, that is the drain hose that you are pointing at. On any conventional two-stroke engine, the fuel/air mix goes through the crankcase on it's way to the cylinders. On most old-design engines there is not much airflow velocity as it goes through the crankcase. That allows some fuel to "rain" out of the air and puddle up in the case. So, to get rid of the puddle, they put in some valves to drain it off and dump it. You know the rest of the story.

 

[F_R]

Re: Oil return line

My '59 Fat-Fufty V4 had the line, I do not know if the '64 has it. On my Fatty, the line ran from the base of the intake manifold (under the carb) to the starboard sie of the motor, to a brass nipple. It dumps raw fuel into the water directly, so the modification will not starve any part of the motor of lubrication.

I took a 1 pint plastic 2 cycle oil bottle and installed a brass hose barb in the cap. I then cut out 1/2 the bottom of the bottle and "wired" it upside down next to the carb. The cut out bottom was next to the intakes, and a hose coming off the hose barb ran back to the gas tank. Now route the fuel/oil purge line into the bottle, and the fuel drips back into the tank, and the vapors are reburnt.

Chris, I appreciate your creativity and it sounds like a good system. If I may add a comment though, are you pretty confident that all the vapors are being drawn into the carb, especially at slow speed when there isn't a whole lot of airflow? I can envision the vapors dispersing around under the hood and the hood becoming a satellite launch if they are ignited by a stray spark. Just thinking out loud.

 

[Evinrude Boater]

Re: Oil return line

On car engines you have a similar sort of thing that ventilates the crank case at the valve cover and the vapours are sucked down the thottle body, right? There's just vapours, no raw fuel.
I remember responses to this previously indicated that a significant amount of fuel is reclaimed by routing this line into the tank or another suitable collection container. From what I see on the water when I raise the engine, it doesn't appear to be much, only when I have a problem starting the motor and I flood it.
The thought of vapours accumulating under the hood makes me leary to make this modification, besides, I see a motor mount is loose or broken. On to my next thread.

 

[F_R]

Re: Oil return line

Those "vapors" coming out of there are highly explosive fuel/air mix, the same stuff that goes into the cylinders to be ignited by the spark plug. The fuel in the "vapors" is finely atomized into a vapor itself. The liquiid fuel that you see draining out is what has settled out of the air. In an ideal situation, if one existed, would be no liquid fuel, only vaporized fuel and air mixed together.

 

[Chris1956]

Re: Oil return line

FR, I ran that system for years, and never blew up. You need to remember that the vabors pushed out the line are a small fraction of the total carberation. The air intake is easily sufficient to suck it all back in, if the hose is near the air intakes....

 

[F_R]

Re: Oil return line

Chris, like I said I admire your inginuity and obviously you have not blown yourself up. I just wanted others to be aware of what is coming out that hose, and be careful what they invent.