Breeze tonight, Gale tomorrow?

[Buccaneer]

Frank, thanks for the explanation on the "pump".
There is a channel routered out in the flange of the
crankcase (where it bolts to the cylinder)
between the top and bottom crank main bushings.
I just thought it was for getting rid of oil in the top
bushing so it didn’t contaminate the magneto.
I guessed that crankcase pressure lubricated the
upper bushing. I didn’t know about the pumping
slot forcing oil up to the top bushing.
Interesting, Thanks!

Prepare to be boarded!

[Buccaneer]

quote FrankR:

Yeah, common in small OMC motors, it acts as a rotary valve that opens when there is pressure in the lower crankcase section and suction in the upper section. That difference in pressure causes oil to flow up from the bottom to the top main. Most such engines have a small exterior hose or tube for the oil transfer.

I guess this system of crankcase pressure differences moving the oil would
not work so well in a single cylinder!

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