1968 Chevrolet Impala Crankcase Ventilation System

What Is the Crankcase Ventilation System?

The Positive Crankcase Ventilation (PCV) system is designed to control and recycle the gases produced within the engine's crankcase. During the combustion process, some gases escape past the piston rings into the crankcase — including harmful vapors such as unburned hydrocarbons and blow-by gases. If left unchecked, these gases can lead to increased pressure inside the engine, resulting in oil leaks, decreased engine efficiency, and increased emissions.

The PCV system utilizes a series of hoses and valves to redirect crankcase gases back into the intake manifold, where a one-way valve — the PCV valve — regulates their flow. When the engine is running, the PCV valve opens, allowing the gases to be drawn into the intake manifold, where they mix with the incoming air-fuel mixture and are burned during combustion. This closed-loop design not only protects the engine internals but also reduces harmful emissions — making the crankcase ventilation system one of the earliest and most important emissions control technologies on modern vehicles.

Key Components of a Healthy CCV System

The crankcase ventilation system is made up of several interdependent components that all need to be in good shape for the system to work properly. Understanding each part helps you diagnose problems and choose the right replacements.

• PCV Valve: The major component in the system, the PCV valve is a simple spring-loaded valve with a sliding pintle inside. The pintle is tapered so it will increase or decrease airflow depending on its position, changing the orifice opening to regulate the volume of air passing through. Replacement is generally recommended every 20,000 to 50,000 miles to ensure proper system function.
• Engine Crankcase Breather Hose: The breather tube is a core part of the PCV system, connecting the crankcase to a clean source of fresh air — typically the air cleaner body. Cracked or deteriorated breather hoses are a common cause of rough idle and oil leaks.
• PCV Valve Hose: A hose connects the top of the PCV valve to a vacuum port on the throttle body, carburetor, or intake manifold, completing the circuit that recirculates crankcase vapors. Like other rubber components, these hoses harden and crack over time.
• PCV Valve Oil Trap: The oil trap (or oil separator) captures oil mist entrained in crankcase vapors before they re-enter the intake, protecting the intake manifold and throttle body from oil buildup and contamination.
• Engine Crankcase Breather Hose Kit: Breather hose kits provide all the hoses and connectors needed to restore the entire crankcase ventilation circuit in one purchase — a smart choice when multiple hoses are aged or degraded.

Why Crankcase Ventilation Maintenance Matters

Over time, the PCV valve can become obstructed or stuck in the open or closed position, affecting the proper flow of crankcase gases. This can result in increased oil consumption, rough idling, and increased emissions. Minimizing oil leaks, reducing oil usage, preventing crankcase sludge, and improving overall engine efficiency are all benefits of a properly functioning PCV system. Inspecting the entire ventilation circuit — valves, hoses, and oil traps — during routine maintenance is an easy way to head off bigger, more expensive problems down the road.

Top Brands for Crankcase Ventilation System Parts

Choosing quality parts from reputable manufacturers ensures a proper fit and long service life. Here are some of the most trusted brands in this category:

• Genuine: OEM-sourced crankcase ventilation components made to the exact specifications of the original manufacturer. These parts offer the most direct fit and are the go-to choice for drivers who want factory-level reliability.
• ACDelco: GM Genuine Parts and ACDelco are the true OE parts installed during production or validated by General Motors for GM vehicles, with maintenance and repair components designed and engineered to meet rigorous standards set by General Motors. ACDelco's Gold and Professional lines cover a wide range of PCV valves and hoses for both GM and many other vehicle applications.
• OEM: OEM-equivalent parts sourced to match original equipment specifications across a broad range of makes and models — an excellent option for technicians and DIYers seeking factory-correct replacements without the dealership premium.
• URO: URO Parts specializes in replacement components for European vehicles, offering an extensive lineup of crankcase ventilation parts for BMW, Volvo, Volkswagen, and other import brands that can otherwise be difficult to source affordably.
• VAICO: VAICO is a German automotive parts brand owned by VIEROL AG with a primary focus on European car brands like VW, BMW, and Mercedes-Benz. VAICO parts often bear the "Q+" quality label, indicating production in factories that supply original equipment manufacturers and certification to European ISO quality standards. Their extensive crankcase ventilation catalog makes them an ideal choice for European vehicle owners.