What happens to crankcase pressure if the PCV system is clogged?

When the Positive Crankcase Ventilation (PCV) system is clogged, the flow of gases from the crankcase to the intake system is obstructed. Consequently, any gases that normally escape the crankcase, such as blowby gases produced during combustion, become trapped within the crankcase. This leads to a buildup of pressure because the gases have nowhere to go.

As the engine operates, blowby gases increase in volume due to combustion byproducts leaking past the piston rings into the crankcase. If the PCV system is functioning correctly, these gases would be evacuated, helping to regulate crankcase pressure. However, a clogged PCV system prevents this evacuation, resulting in an increase in crankcase pressure due to the accumulation of these gases. Therefore, the correct answer reflects this increase in pressure due to the hindrance of gas escape.