Pcv Valve Issue (i Think)

[jjman]

Hey, tried searching the threads and asking mechanics for an answer to the issue here but no luck...

Basically it seems that my PCV valve is making a hissing sound at idle and it didnt use to.

Im pretty sure its the PCV as iv replaced the gromet and the hose that connects it to the plenum with genuine items (so its not a hose leak). Also the noise goes away if you hold that hose to the plenum shut with your fingers (so no air can flow thru that pipe and the PCV). It also stops hissing when you rev it a bit, closing the PCV valve as it would normally under throttle i assume.

The problem is i stuck another second hand PCV valve in there today and the same hissing sound is still present...

Do PCV valves make a hissing sound when they are knackered and perhaps this second hand PCV valve was also finished or is there perhaps something else at play here trying to flow more air than normal thru the PCV and resulting in the hissing?

Is there meant to be a restrictor in any of the hoses of the rocker covers that might be missing?

Just trying to get to the bottom of it before i order an $80+ new PCV from japan that will take 3 weeks if it isnt the issue....

And knowledge or ideas would be greatly appreciated.

Justin

Edited November 10, 2010 by jjman

[JonnoHR31]

they usually hiss but normally you only notice it if you pull it out of the rocker cover with the engine running. if its not leaking i wouldnt worry about it

[mad082]

at idle (and anytime when the plenum is seeing a vaccum rather than positive boost) the pcv will be open and the engine will be sucking air out of the rocker covers (that is why squeezing the hose stops the sound). once positive pressure builds up it closes the valve.

[jjman]

Right you were, normal behaviour.

Anyways iv since done the 'block the pcv hose' mod and catch-caning the breathers. Not a fan of any sort of oily vapours going into the plenum or in front of the turbo.

Sorted