When no vacuum is felt in the PCV valve, what could be the possible reasons?

When no vacuum is felt in the PCV valve, it indicates that there is an issue in the positive crankcase ventilation system that is preventing proper airflow. The correct answer includes both scenarios where the PCV valve may be stuck closed and where the hose could be plugged.

If the PCV valve is stuck closed, it means that it is not allowing the gases from the crankcase to pass into the intake manifold, which results in a lack of vacuum at the valve. This can create excessive crankcase pressure, leading to oil leaks or increased emissions due to unburned gases.

Similarly, if the hose connecting the PCV valve to the intake manifold is blocked or plugged, it also impedes the flow of gases, leading to the same symptoms: a lack of vacuum in the valve, failed ventilation, and potential engine performance issues.

Thus, both factors are critical reasons for the lack of vacuum at the PCV valve, making the choice that includes both possibilities the most comprehensive and correct. Understanding that both conditions can independently or together cause this issue is essential for diagnosing and fixing crankcase ventilation problems effectively.