Reply To: 1963 Evinrude oil leak

[David Stanton]

I’m sure at least some of what you are seeing is exhaust residue.  Each piston stroke that doesn’t fire puts a cylinder-full of oil/gas-vapor mix down the exhaust, and when starting cold with the choke on, it’s a rich mix.  Then, until you get it running smooth, firing each cylinder every time, it continues to put unburned gas/oil mix down the exhaust each time a cylinder doesn’t fire.  Some of this comes out in the water where the oil floats to the surface, where it spreads out and looks like more than it is.  This unburned gas/oil also coats the inside of the exhaust housing and combines with the combustion residue to turn black and some slowly drains out later unless it is given a high throttle run for a while on a boat to clear it out.  Until you have adjusted the high speed carb jet on a boat at wide open throttle, it will not be set right unless you have a test-wheel (which most all of us don’t have)  instead of the prop, so could easily be set too rich.  The bullnose shape of the high speed “needle” is correct.    Before dumping your water barrel, squirt some liquid dish soap on top and you will see the floating oil rapidly turn into a more environmental-friendly goop.  These motors do drink their share of gas at idle speeds, and if the float level is set right, and the carb doesn’t leak gas when the primer-bulb gets firm and is squeezed a bit more, the carb is likely OK.   The pressure test on the gearcase the other guys mentioned is best way to test the gearcase for leaks.

Dave