Crankcase Breather and PCV Valve

[Tham]

In the 4K engine, there's a crankcase breather port
just in front of the PCV valve grommet, and behind
the oil filler cap, connected by a short L-shaped hose
to the air filter housing, where it opens up just behind
the air filter.

Is this crankcase breather an inlet system (drawing
air from the air filter) or an outlet system (venting
blowby from the crankcase to the air filter) ?


Secondly, if I remove the PCV valve hose and plug
it off, leaving the valve itself sticking on its grommet.
would the valve still be able to ventilate some blowby
gases into the open air (from the blowby pressure
forcing the valve open) ?

[MWP]

Normally the breather is both, an inlet and an exit.

You should leave the PCV system as per the factory setup if possible.
It is there to remove blowby gasses from the crankcase which pollutes the engine oil.

When at idle, cruise and overrun the crankcase gas is pulled out via the PCV valve, and fresh air is pulled in via the breather.
During acceleration, the PCV is closed, and gasses vent out the breather.

[Tham]

Thanks for the info.

I disconnected the PCV valve, as the engine is aging with
loose piston rings and valve seals, so the excessive and
dirty blowby tends to clog the valve pretty fast.

You mean if the outlet side of the PCV valve is disconnected
from the manifold hose and left there in its grommet, it would
remain permanently closed, with no blowby gases coming out ?