40TLRB check valves

[DougBradlow]

Hello,I was wondering if anyone could tell me what the check valves are for in my block and crank case? I have check valves with hoses going to and from the block and crank case,What are they for?Just wondering if I should replace them or not. Thanks.

[99yam40]

I am fairly sure they are to drain the liquid fuel out of the crankcase (not all vaporizes and is burned in cylinders)
The check valves make sure the flow goes one way