Suzuki: 2008 Suzuki grand Vitara 2000 petrol, oil filler cap, suzuki grand vitara

Question
Today the oil dipstick dislodged itself and spattered oil in the engine compartment.
On putting it back securely, I checked with the engine running.
There was a good bit of back pressure.
So I then undid the oil filler cap, to  find quite a bit of back pressure.
Is this normal ?

Answer
There's usually a vent hose from the air cleaner to a valve cover.
There's also a PCV valve that pulls crankcase vapors into the intake to be burned.  The vent hose allows for replacement filtered air into the crankcase.
It's probable that your PCV valve is plugged and should be replaced.