rocker cover breathers

On the rocker cover we have 2 breathers.
On the standard setup the one by the filler cap is setup to a vacuum system and the other goes to the intake pipe.
I have removed the vacuum system and the other side I have put to a catch can.
My question is this.
The one by the filler cap has a valve in it and because it has been removed from the vacuum system that valve no longer works so it is now blocked?
I have seen people run a hose from it to the catch can. But because it opens and closes under vacuum surely that's a waste of hose because it does nothing? Or do people change the fitting to ine without a valve.
As you can see in my picture mine has nothing on it.
Shoukd I remove the valve nd fit one without a valve so the engine breaths better?

Personally I would think if you connect a breather/catch can to this connection its not going to do much unless its connected to some sort of vacuum source. In fact if this additional breather is simply a catch can vented to atmosphere then you're practically introducing an inlet air leak as the main breather (assuming connected to inlet tube) could suck unmetered air through the cam cover and not the blow by gas out of the crankcase. If you left the check valve in place and connected this to a catch can then it would almost definitely need to be plumbed to the inlet somewhere in order to operate. The only time this might actually do something is if the internal pressure of the engine becomes so much that it opens the valve and pushes gas out (like a pressure relief valve). At least the check valve would stop the main breather sucking in fresh air though.



On my last R I simply removed all that breather/vacuum pipes and blocked off the valve and installed a catch can between the head and inlet...it ran fine like that for a good 3/4 years before I sold it and as far as I know is still going strong.



I've got a catch can to be plumbed in to the main breather to the side of the head (probably like yours) but I think I'm going to buy a smaller one to plumb in between that check valve and the rats nest of vacuum/breather tubes on the manifold. At least then the original PCV system is still there, but with the addition of two catch cans to prevent oil ingestion.


I've probably not helped much have I, lol!

Lol thanks Mike.
You have confirmed my suspicion mate.
My pcv setup has been removed and it has run like this since 2009 to my knowledge.
I had some spare time to think tho and this was what I thought about haha

I don't want to put the rats nest back as it just puts the gasses and moisture into the inlet which isn't the best thought out design as surely it messes with the fuel mixture?
I don't know tho. I'm just over thinking here.
Guess I will leave it for now. Or maybe I will take the valve off and knock the valve out and re install it so the engine breaths from that side too?
Does it need to breath at both sides is my question I guess?

Personally I would let it breath as much as possible. Not saying it won't work but I know one thing these cars are a lot better than people know. Improve standard set up but any major changes away from it bring problems in my opinion

By that statement I am not saying the car is not going to run fine but you know what I mean

Have a read of this.

https://www.google.com.au/url?sa=t&source=web&rct=j&url=http://www.shophemi.com/images/media/p-2273-arrington_ccv_bible.pdf&ved=0ahUKEwj6mqqG3MbSAhUIybwKHY4oB78QFggbMAE&usg=AFQjCNG9AQSA-i20utzGu9PzCRxA6RfS_Q&sig2=mzM4BbHQnZ6OvbFRJgxDJA

ducie54 wrote:Have a read of this.

https://www.google.com.au/url?sa=t&source=web&rct=j&url=http://www.shophemi.com/images/media/p-2273-arrington_ccv_bible.pdf&ved=0ahUKEwj6mqqG3MbSAhUIybwKHY4oB78QFggbMAE&usg=AFQjCNG9AQSA-i20utzGu9PzCRxA6RfS_Q&sig2=mzM4BbHQnZ6OvbFRJgxDJA

Thank you for sharing that.
Interesting read and very Informative!
I think I need to get the standard pcv bought and installed again..

If you running any more than stock boost I would run a proper one way check valve between the intake manifold and the PCV valve. I got mine from boomba racing, they do several sizes.

http://www.boombaracing.com/check-valves/

I would also take note on oil temps. To low and it won't burn off water/fuel.

If your after some more info check out these guys. http://www.conceptualpolymer.com/Documents/pcvor.pdf

Looking again at your picture, you've already got 90% of the breather plumbing there (of sorts) as the tubing looped between ports on the manifold. If you manifold them together with tee's and connect your one way valve and this to a catch tank then that's job done. I think the original breather setup ties into the manifold before the butterflies (next to the ports with the rubber bungs) to give good vacuum at idle so it should work ok and would save re-installing that mess of a rats nest 

Thanks guys.
I will see what I can do by retro fitting a pcv setup on like you said with T pieces Mike.
I will have a look at those one way valves too

That's some really good info, going to read the whole thing when I have time. Makes me rethink my setup.

This is how I have mine Stu



Left side PVC valve has been taken out for a hollow one and a folter put on the end to it just vents to atmosphere.

Other side has been plumbed to a catch can then back into the intake to replicate the stock setup but stop it pushing oil back into the turbo and catch it. I think this way ensures the engine can still breath freely but is neater for none stock setups. You dont want a badly breathing engine as that will cause issues.

shroom wrote:This is how I have mine Stu



Left side PVC valve has been taken out for a hollow one and a folter put on the end to it just vents to atmosphere.

Other side has been plumbed to a catch can then back into the intake to replicate the stock setup but stop it pushing oil back into the turbo and catch it. I think this way ensures the engine can still breath freely but is neater for none stock setups. You dont want a badly breathing engine as that will cause issues.

I was thinking of going from the catch can to the intake.
I had it going from the rocker to the intake and it was suckling oil into the intake pipe. Or the vapours were gathering and making small oil residue?
But from the catch can to the intake pipe shoukd illuminate that?
I think I'm still going to reinstall the pcv setup. Only not all the oe stuff..

In my last R I tried running it without the black separator thingy (top right of engine) and it spewed oil out into the catch tank. I reckoned it must have doubled as a baffle too to stop the PCV sucking the sump dry so was absolutely critical. If you reinstate that and connect it to the catch tank then the inlet tube that would do it dandy. It's still debatable whether or not you need the breather at the back of the engine but I guess Nissan put it there for a reason so no excuse not to have something there

My pcv valve is removed, and just using a normal fitting and that goes to the catch can, the crankcase breather hose goes up to the rocker cover t-piece (black box removed) and then the t-piece also goes to the catch can. Catch can then vents into the intake pipe.