Tractor Repair: 65 Massey Furguson-gas engine, massey furguson, air intake system

Question
I have gas getting into the crankcase. What can be the cause?

Answer
The only thing I have ever saw cause this is the needle valve in the carburetor leaking when the engine is shut off & filling up the air intake system to the point it will seep over into the engine. When this happens the engine will usually blow black smoke when it is first started. There is no other place the Gas can get into the engine. Big Dean