D6 9U Gas in oil of Pony?

I put gas in the pony motor tank yesterday. When I went out today all the gas was gone in the tank and it appears that it went all down into the crankcase. Can someone tell me what caused this and how I can fix it?
Thanks

What you need to do is have the gas turned off at all times but only turned on to start and run. When you want to start the diesel turn the gas on and when the diesel starts then turn the gas off with the starting engine running yet and let the gas burn up in the carb.till it stalls out.You didn,t say if you started the diesel and ran it after you filled it with gas and let the gas turned on or not.If it wasn,t run and ran down in the oil maybe the float is bad or the needle and seat for the float control is shot or stuck open.

Drain the Gas\Oil out of the pony crankcase immediately. Main and Rod bearings don't like to be coated with gasoline! Check to see if fuel shut-off valve is working properly. Disconnect line at pony carb and with the shut-off valve closed, see if gas is still running or trickling through the line. If not, as SJ said, check float at carb etc. Good luck in finding the problem.😊