What is a PCV (Positive crankcase ventilation valve)? How does the crankcase breathing valve work? What are the signs of a failed PCV valve ?….
What is a Positive Cylinder Ventilation Valve?
Even the best engine design, flammable gases can escape through the piston rings into the oil pan. To prevent engine damage or environmental disaster, all cars manufactured before the 1950s emitted unburned gas. Hydrocarbons (unburned fuel), Carbon Monoxide (partially burnt fuel), particulates and water are all examples of these gases. These chemicals corrode all metal components that they touch, displace the engine oil, cause oil to sludge, block small passages and hoses, and also corrode them. The sump system must be ventilated, and unburned gas should not be released to the environment. Since the 1960s, automakers have produced vehicles that use positive crankcase ventilation (PCV).
The PCV system removes unburned gas from the crankcase and returns them to the intake manifold to be burned when conditions permit. The PCV system prevents crankcase pressure from rising, which can cause oil leaks by causing damage to oil seals and gaskets. Additionally, engine oil would become muddy from moisture and other waste gases, which would lead to engine component wear due to oil loss.
How the PCV Valve Worked
The PCV Valve is a simple device that filters clean air and delivers it to the crankcase. The valve draws air from the crankcase using engine vacuum and returns it to the intake manifold. To regulate the flow of unburned gas, there is an internal one-way check valve that has a spring-loaded piston. The valve’s one-way valve connects to the manifold vacuum, while the other connects to the engine’s valve cover. When the engine is turned off, the internal spring in the PCV valve forces a check valve to close. The manifold vacuum opens the check valve when the engine turns on. Fresh air is then sent to the crankcase through a vent pipe. This creates a sweeping effect that drags any unburned gas towards the PCV valve. Through a rubber tube, the gases from the PCV valve are directed to the throttle body or intake manifold. It is then sent to the engine where it will be burned.
PCV Valve Malfunction Symptoms
Many systems use a PCV to regulate the flow rate of crankcase gasses. This task can be accomplished by an orifice tube, separator or other device. As with any automotive component, the PCV can eventually fail and cause symptoms. A PCV valve malfunction could be suspected if you observe any of the symptoms listed below.
Manufactured oil is not available
In high vacuum conditions, the valve should be kept closed. If the valve is left open, the crankcase will be drained of oil. It can also cause oil loss and burning inside the engine.
Misfire / Idling Stop
The PCV valve draws gas and air from the crankcase to the engine. The engine’s air-fuel mixture can deteriorate if the valve is left open. This can lead to idle fluctuations, misfires and the vehicle stalling.
Engine Malfunction Light On
Modern vehicles have an on-board computer (PCM), which monitors the functioning of the PCV systems. The PCM will store the fault code and turn on the engine fault lamp to alert the driver if it detects an issue with the PCV system. A stuck PCV valve can cause misfires and trigger the engine light.
Lubrication for the Air Filter
Unburned gases can build up in the PCV valve if it is not in its closed position. They will eventually be sent to the housing’s air inlet/air filter housing and cause the filter to lubricate.
Oil Leaks
A stuck PCV valve in its closed position can increase crankcase pressure, and cause damage to oil seals and gaskets. Oil leaks can be caused by oil seals that are worn or burst.
Engine Oil Deterioration
If you ignore a blocked PCV valve, moisture can build up in your crankcase and cause engine oil to become muddy.
A faulty PCV valve could cause damage to the seals, increase oil consumption, and possibly engine damage. It should be replaced as soon as possible. Many automakers recommend that you replace the PCV valve as part your vehicle’s routine maintenance program. The maintenance schedule can be found in the owner’s guide. The rule of thumb is to clean your PCV valve at least once every 50,000 to 80,000 km. To change between.
Failure Symptoms: PCV Valve Stuck In Closed Position
- – Illumination at the check engine lights
- – Increased engine pressure
- – Failing one or more oil seals, gaskets
- Leakage of engine oil
- – A whistling sound or groaning sound coming from the engine
- – Sludge and moisture build-up in the engine
- – Engine speed fluctuations
- – Setting fault codes in relation to the MAF sensor
- – P0171 rich and lean fault codes are set
- – Setting fault codes in relation to oxygen sensor O2
Signs that your PCV Valve is stuck in an Open Position
If the PCV valve is not closed, or if a system line becomes disconnected, torn, or becomes disconnected, you will experience one or more of these symptoms.
- – Illumination at the check engine lights
- – Engine misfires when idle
- – Air-fuel mixture with low omissions
- – Prevalence of engine oil in PCV valves or hoses
- – No engine oil
- – Hard start
- – Engine stalls at idle
- – Exhaust fumes emitting black smoke
- – Oil contamination of spark plugs
- – Triggering fault codes for MAF sensors or oxygen sensors
