i need some pcv valve guru's to help me out.
i have read some lengthy articles on a few different sites and still cannot find an answer to my question.
when is the pcv valve supposed to close and when is it supposed to open?

from what i have read, it is supposed to open when the intake manifold pressure is lower than the crank case pressure. and close when the manifold pressure is higher than the crank case pressure.
the reason for that is so that none of the gas vapors that may be present in the manifold can be blown into the crank case and cause the oil to break down.

what i'm not sure about is, should the pcv valve be open or closed at idle with the truck at operating temp?

the other day i heard a high pitched hissing noise coming from the engine and after wiggling the cai a little bit to check for a gasket leak, i grabbed the pcv valve hose and wiggled it a little and the hissing went away.
after tightening the hose clamp by the manifold i realized that touching the hose made the pcv valve open and the hissing was from it being closed.
if i mess with it for a second i can get the pcv to stay open and you can hear the pin inside it rattling around. but if i touch it again it closes and the hissing comes back because of that.

hopefully i gave enough info and it isn't too confusing. to sum up the questions, is my pcv working correctly or should i get another? and should it be open or closed at idle?

 

I have no idea. But they are so cheap, just get a new one. Make sure you get Mopar, not a store brand. I bought a Fram once and it didn't work right. Man, is anything Fram makes work right?

 

frams stuff used to a while back before they go bought out. then again, their air filters are ok. restrictive but ok.

i'm only asking because i want to know if it is working like it is supposed to or not.
my ac started working right after putting this pcv valve in and i have no running issues so i don't think i need to replace it.

 

The PCV gets opened when the internal crankcase pressure exceeds manifold pressure by whatever amount it takes to push the pintle upward. Excess crank gases get pulled into the manifold to avoid dumping them into the environment. If the PCV doesn't jiggle up and down freely, get a new one.

In the old days, there used to be a metal tube that hung down toward the street and the opening of the tube was facing backward and was cut upward at an angle. The negative pressure on the back side of the tube pulled the gases and oil vapor out where it landed in the center of the road and got slicker than snot when it rained. That's where the old rule of motorcyclists never driving down the center of the street came from.

 

well it does jiggle, its new. i was basically asking if the crank case pressure would be lower than the intake at idle because mine wants to close when its idling.
if i tap on it with my finger (when the engine is idling) or grab the hose and wiggle it a little then you can hear the pintle rattling around because the pcv opened. but if i don't touch it then it will stay closed.

 

hell, i don't know
but i do know, this is why i like working on farm equipment, no emissions bs, there is simply a tube that points down towards the dirt, that blowby is vented from

 

Same thing with the diesel engines in big trucks. They just have a vent tube that points to the ground.

 

That was called a "road draft tube" by some and was called a "crankcase vent" by others.

 

yep yet another good name sold to inferior manufactuers for quick profit I read an article that compared oil filters and fram is one of the worst to run....they actually use cardboard in thier filters and in many cases they fall apart internally!.... sorry back on topic

 

Fram has used cardboard ends on the filtering element for over 20 years.