But today, the valve has been consolidated to perhaps a few dozen applications. Its job was to direct a measured amount of vacuum from the intake manifold into the crankcase, pulling oil vapor into the intake manifold where the oil was burned.Īt one time there were probably hundreds of different PCV valves – all specific to individual engines. The very first emissions device was the positive crankcase ventilation (PCV) valve. If you look at old photos of the freeways in Los Angeles from the early ‘60s, you will see a black stripe of oil centered in each lane from the oil dumped on the road from these road draft tubes. Let’s start with a quick review of what the PCV system is and how it works.īefore 1962, cars merely dumped crankcase vapors overboard. Often, it’s just a matter of getting the car to perform the way you want.

Not everybody is concerned with peak horsepower. Jeff Smith: Sometimes the smallest details can make a big difference in a daily driver. I was thinking of buying one of those big oil separators. But even with a piece of cloth (it’s just an old sock!) around that big breather, it still drips oil on my valve covers. I had a PCV valve on the engine, but at highway speeds it would sometimes push out the dip stick so I removed it and just put a big breather on the valve cover. I have a 472-cubic-inch engine in my ’69 Cadillac and I have a problem with oil vapor covering my nice new aluminum valve covers.

Pcv valve hose connector