What does an air breather do?
"An air breather replaces the intake vent hose on your crankcase, which vents the spent gases inside your head out into the atmosphere instead of back into your intake track. This keeps your engine clean."

I got the information above from some website, and also heard the same from a mechanic... If the above information is true, why did manufacturers put a hose from the crankcase to the intake tube? Is there a benefit for the air intake tube to be receiving the released gas from the crankcase/valve cover?

Thanks.

 

rice. use a good PCV/catch can system.