Which technician is correct about the PCV valve indicating vehicle operation?

Which technician is correct about the PCV valve indicating vehicle operation?

• A. Technician A
• B. Technician C
• C. Technician B
• D. Technician D

Answer: (C)

Understanding how the PCV valve indicates engine operation hinges on how this vacuum-driven valve controls crankcase vent gases. In normal operation, engine vacuum pulls the PCV valve open so crankcase vapors are drawn into the intake, and you should feel a steady vacuum at the valve when the engine is running. A quick, practical check is to shake the valve with the engine off; a good PCV valve will rattle, showing the internal plunger and spring move freely and that it isn’t clogged. If the valve doesn’t rattle, or you don’t feel vacuum in the line when the engine is running, the PCV system isn’t functioning properly, which can signal improper engine operation or potential buildup of crankcase pressure. Technician C is correct because this behavior—the presence of vacuum under operation and the audible or tactile indication of a free-moving valve when tested—matches how a healthy PCV valve should indicate vehicle operation.

Understanding how the PCV valve indicates engine operation hinges on how this vacuum-driven valve controls crankcase vent gases. In normal operation, engine vacuum pulls the PCV valve open so crankcase vapors are drawn into the intake, and you should feel a steady vacuum at the valve when the engine is running. A quick, practical check is to shake the valve with the engine off; a good PCV valve will rattle, showing the internal plunger and spring move freely and that it isn’t clogged. If the valve doesn’t rattle, or you don’t feel vacuum in the line when the engine is running, the PCV system isn’t functioning properly, which can signal improper engine operation or potential buildup of crankcase pressure. Technician C is correct because this behavior—the presence of vacuum under operation and the audible or tactile indication of a free-moving valve when tested—matches how a healthy PCV valve should indicate vehicle operation.