PCV systems vent off a POSITIVE crankcase pressure that arises from blowby - a mixture of air, fuel vapor, and
oil vapor forced past the piston rings into the crankcase. If you don't vent this pressure it will eventually find its' own way out - past a gasket somewhere, generally.
You do NOT need a breather to make this system work - on the contrary, a breather circumvents proper operation by giving the system something to consume OTHER than crankcase vapors. What you do need is a properly-sized PCV valve, one that is sized in accordance with the expected volume of vapor.
This is why PCV systems replaced breathers in the first place. Breathers allow those vapors out into the atmosphere; PCV's pull them back into the engine to be burned off with the normal mix.