How does a positive crankcase ventilation (PCV) system work?

Author's Note

It sometimes amazes me how much thought has gone over the years into the ways that cars work and how some of our ideas about automobile construction have changed over time. Today, emission control is an extremely important part of automobile design, because it minimizes the amount of pollutants that escape into the atmosphere and degrade the environment. While researching this article I was impressed to learn that the idea of emission control began almost exactly half a century ago, with the invention of positive crankcase ventilation and the PCV valve. Of course, there are much more advanced emissions control systems available today and cars with zero emissions are already possible -- electric cars have no emissions at the tailpipe, though emissions may be produced when the electricity is initially generated -- and within a few decades, when internal combustion engines in cars have become obsolete, automotive emissions may be a thing of the past. When that happens, we can thank the inventors of positive crankcase ventilation for leading the way.

Related Articles


  • Bastias, Dr. Pedro, et al. "Air/Oil Separator with Minimal Space Requirements in the Crankcase Venting System." (May 15, 2012)
  • Blackwood, Jim. "Positive Crankcase Ventilation." British V8. (May 15, 2012)
  • Conceptual Polymer. "PCV Line Removal 102." (May 15, 2012)
  • "Positive Crankcase Ventilation." (May 15, 2012)
  • University of Missouri. "Positive Crankcase Ventilation System." (May 15, 2012)
  • Yahoo Autos. "What is the PCV valve and what does it do?" (May 15, 2012)

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