[ChevLoRay]

An internal combustion engine is merely an air pump. In order to compress the air, it has to breathe. All of the breathing that needs to happen, needs somewhere for the excess crankcase pressure to vent. Prior to PCV valves, engines had a "road draft tube". If you've ever seen an engine that had one, especially when it was nighttime, you would frequently see the smoke from the crankcase as it came out under the car body.....if it had some blow-by. Engines back in the day, didn't last like these engines do today. So, seeing the blow-by coming out of the tube wasn't a biggee. Virtually all of the engines did it. Sometimes, the oily vapor was wet...and would drip on the road and in the garage and on the street and driveways where you parked. It was just another way to track your movements.

I think the Privacy Laws were drafted to prevent oil leakage from engines and that required the PCV system to be installed on all new vehicles.....makes as much sense as some of the other enviromnental laws we have to endure....