The whole idea of PCV is to introduce clean air into the engine, not dust-contaminated outside air, then pull the crankcase vapors into the intake and burn them rather than allowing them to escape into the atmosphere from a road draft tube. The tree-huggers in California started the practice about 50 years ago, but to everybody's surprise, engine life improved dramatically because dust was not getting pulled into the engine with the ventilation air. I was at a seminar for yacht owners several years ago sponsored by Detroit Diesel when the question was asked "How long will a Detroit engine last before it needs an overhaul?" The answer was simple- - - -"Long enough for it to eat 10 pounds of dirt!" The cleaner an engine runs, the less wear happens. If you pull the crankcase ventilation air from the air filter after it passes through the filter element, that's the best source. Next best is a filtered oil filler cap, a breather such as the one in the link with a foam packing inside, or some other way to strain the dust out before the air goes into the crankcase.
Does that explain the situation better than a bunch of smart-donkey remarks designed to ridicule your understanding of how the vent system works?
Jerry
