Hello,

I have a 1997 Junk150 with the 5.4L. The PCV valve rattles like crazy at idle when cold. As soon as I give it some gas it stops. I just replaced the old PCV valve because it was doing the same thing and it was cheap. It stops making the noise when the truck is fully warmed up at times, other times it still rattles. Is there something I should be looking for?

Thanks

 

Is the PCV vavle made out of metal? I have a replacement one that I bought at Pep Boys made by Purolator, I think. I noticed that the valve is spring loaded and when at idle sometimes depending on the amount of vacuum applied to it the thing will "resonate" so to speak. In other words the thing opens and closes really fast and you are hearing the metal to metal of the valve opening and closing because there is not enough vacuum to hold it fully open. That's what I suspect is going on, but I could be wrong. The Motorcraft valve is not spring loaded and the valve moves freely back and forth if you shake it.

 

Could be wrong but, I always thought the PCV valve should rattle when you shake it.

If it does not rattle it is clogged up and should be replaced. I just sprayed mine with carb cleaber to make sure it would rattle.