I just bought a couple of PCV valves one for my 03 tacoma (V6) and a ford focus (zetec) Well I was wondering how do I tell if the Valve is bad or needs replaced? I changed the one on the focus, I could not tell a difference between the new and old (I could blow through both sides of the valve and air passed through) the Tacoma though, I tried blowing through the OEM valve and it would only blow through one way, while the new replacement I could blow air through both directions. I am guessing the replacement valves (and the OEM Ford PCV) are defective because air should not pass both ways, correct?