It works just the opposite. When there is vacuum it is closed , so that it does not suck oil out. So what is actually happening is the PCV valve is not closing. They make elbows you could use or even put the breather directly into the valve cover.If you are worried about the motor not breathing but it is not needed, it will be fine with the pcv valve still in. I will try to post some pics but I have to borrow a camera to do so. shawnOriginally Posted by Zorak