PCV orientation

[NZS2]

Which way round does the valve sit?...flat side facing forward or upward?

Cheers

[Knight Rider S4]

post 27

http://www.s2forum.com/forum/showthread.php?t=18258&page=2&highlight=pcv

[newsh]

Flat side forward

[S2central.net]

Yep

[NZS2]

Thanks guys

[Ross]

Just checking this, as I'm currently taking my PCV system to bits and cleaning it, and replacing the nastier bits from the PCV system that came off my old engine.

Question - what would happen if you ran with the PCV valve installed the wrong way round?

[mcandmar]

It wouldnt work

Think of it as a one way valve, allows air to be sucked out of the crankcase but not in.

[Jamo]

It's a one way valve if that answers your question.

[Ross]

OK, makes sense, it allows pressure to be released from the crankcase but stops it becoming pressurised when you're on boost, right?

So I'd be right in saying...

If it were the wrong way round, then it would be as if there was no PCV system - except when on-boost and then you'd pressurise the crankcase.

[mcandmar]

I dont think so, the breather connects to the turbo inlet hose so it shouldnt see positive boost pressure. The valve itself is unusual, does a little more than a simple one way valve as it has a spring loaded membrane inside. From memory the family album refers to it as a pressure regulator valve.

[Jamo]

The valve is open when it sees vacuum from the inlet manifold and turbo hose and closes if boost pressurised at the manifold AFAIK.

[Ross]

Good point there Mark! Doh!

Guess then it'd just not work, valve would always be closed. Point is, the new engine will have the PCV valve the right way round

[S2central.net]

As I understand it ... that PCV valve is always open... It opens in varying amounts wrt crankcase pressure. It might be shut with zero pressure - I can't remember. But the PCV system always vents to the MAF hose cos regardless of whether the IM is in boost or not - there is *always* vacuum on the MAF hose where air is being sucked into the turbo.