What is PVC?

Positive Crankcase Ventilation is a helpful system specially designed to remove harmful vapours from the engine, and most importantly, preventing them from seeping into the atmosphere giving off harmful emissions classed as hydrocarbons. The PCV system averts this by using manifold vacuum to draw vapours from the crankcase into the intake manifold. It essentially “recycles” gases back into the engine for it to burn.

Blowy-by gases occur when a continuous amount of gases such as unburned fuel, combustion gasses and air leak from the combustion chamber. This causes a sludge or dilutes the oil. Installing a crankcase “breather” can prevent oil mist and vapour from entering the air filter, drawing in fresh air instead.

This is important for the car as a bad PCV valve could have a lasting effect and cause permanent damage such as:

  • Engine oil leaks
  • Engine surges and the possibility of black smoke
  • Sludge and moisture infiltrating the engine
  • Excessive oil consumption


Why does this help?

Similar to how you would need to ventilate an office filled with indoor air pollution with a ventilation system, a car requires the same level of care and attention. Pollution can have an extremely harmful effect on the planet so it’s important that you look after the valve, not only for the sake of the environment, but also to help with the healthy running of the car.

As a rough recommendation, you should change your PCV valve every 20,000 to 30,00 miles. This does entirely depend on the design of the system, how often the oil is changed, and the driving conditions your car is usually put through.

Clean it

Instead of changing your PCV valve, poor ventilation might just mean it needs cleaning. This is easy enough to do with the right equipment. You need to immerse it in solvent recommended by your car manufacturer or local garage. A clean valve should show no signs of sludge or discoloration, if this occurs then it may be time to change the valve.

The result

A good PCV valve can save on any extra stress when it comes to keeping your car running smoothly, and ultimately save you money in the long run if you look after the valve to begin with. Bare in mind that not all engines have PCV valves, if you’re unsure how it could work with your car, contact your mechanic for professional advice.

Crankcase Ventilation