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Anyone tried deleting the PCV check valve??

Discussion in 'A3/S3 Forum (8L Chassis)' started by HTC, Apr 16, 2008.

  1. HTC
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    HTC Active Member

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    [Apr 16, 2008]
    I was just giving my car a once over be for a remap on Monday when I found a boost leak in the PCV system under the inlet manifold.

    Pic of area (pipes removed)

    [​IMG]

    [​IMG]

    [​IMG]

    No real issue I though so I bought some new pipes and a new non-return valve that sits in the tee piece as the old one was leaking. However, the new non-return or check valve also does not hold pressure in a simulated boost situation (my gob blowing into it :laugh:). Also checked with a mates valve too, same result.

    This is a constant boost leak in my opinion which allows boost into the PCV and a badly designed weak valve.

    So now I'm thinking of removing this valve altogether and only allowing crankcase gasses to vent into the TIP. I can't see the point of the small pipe to the inlet anyway. Anyone else tried removing the valve?

    Thanks.
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  3. Prawn
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    Prawn My other car is a MINI!!!!

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    [Apr 16, 2008]
    Let us know how you get on Kev, I was thinking of installing a catch tank in my PCV system to try and limit the insane amounts of oil that is being vented into my TIP and slowly filling up my intercooler!

    I wasn't aware of the system in your pics under the inlet, very interested to see if mines a problem at all. My car is still only holding 10psi to the redline. I'm going to try bypassing the N75 tonight to see what my wastegate is set at, and if thats not the issue, I'll check out those PCV pipes.
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  4. simch
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    simch Active Member

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    [Apr 16, 2008]
    is the pcv the little lack placky valve in the rubber hose from the maf to the tip, sort of positioned near to the dv?
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  5. Bellic
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    [Apr 16, 2008]
    how do you check what your wastegate is set at , i have a forge on mine but need to get it set right what should it be reading on gauge is it 0.4?
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  6. HTC
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    HTC Active Member

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    [Apr 16, 2008]
    This is indeed the pressure control valve for the crankcase breather system. If you look at the second pic, it connects to the pipe end on the far left.

    I've emailed JBS to get their opinion. I think I'll block the thin pipe to the inlet tomorrow and see how the car drives.
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  7. simch
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    simch Active Member

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    [Apr 16, 2008]
    There is an interesting thread on ukmkivs about boost leaks from the pcv and one guys thinks is the rocker cover on his agu.
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  8. HTC
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    HTC Active Member

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    [Apr 17, 2008]
    Do you have a link to the thread?
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  9. HTC
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    HTC Active Member

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    [Apr 17, 2008]
    Had the breather apart again today. The new valve is faulty I'm sure, but the old valve holds pressure when it has a film of oil within it. I wonder if this intentional? Just been out for a drive and the car is real quick. I was only boosting to approx 15psi after the turbo swap. Now it will boost past 20psi. Couldn't really boot it as fueling isn't right.

    Roll the remap on Monday!

    If it starts to leak in future, I've got a spare check valve from a brake servo pipe that I'll add.
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  10. Prawn
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    Prawn My other car is a MINI!!!!

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    [Nov 24, 2009]
    Monster bump:

    Kev, you're possibly my favourite person right now.....

    I've just dug up this thread and had a look at what you found, then gone and compared it to my car outside, to find the hose under my inlet manifold is FAR worse than yours in the above pics.

    I'm REALLY hoping this could go some way to explaining my boost problems now!
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  11. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    [Nov 24, 2009]
    Hope you get it sorted now mate.
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  12. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Nov 24, 2009]
    I told you these cars are a nightmare! Hope this sorts you out and saves you buying a new turbo!
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  13. 1animal1
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    1animal1 The Clar!! it mouves!!! VCDS Map User

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    [Nov 24, 2009]
    hmmm, just trying to see the downside to this mod IF you have a catch tank fitted? essentially the catch tank is a direct replacement for this valve surely.....
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  14. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    [Nov 24, 2009]
    All the sc.net guys get rid of the mushroom valve and just replace with a 90' elbow.
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  15. 1animal1
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    1animal1 The Clar!! it mouves!!! VCDS Map User

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    [Nov 24, 2009]
    yup and plumb in a catch tank like yours yeah?
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  16. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    [Nov 24, 2009]
    Yup, by the way mine does work tim :icon_thumright:
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  17. Prawn
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    Prawn My other car is a MINI!!!!

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    [Nov 24, 2009]
    yea, the SCN guys just delete the vacuum feed altogether, and let it vent to the catch tank before anything returns to the TIP. in reality, if the engine has enough breathers, the PCV system shouldn't be needed, and it should be more than OK venting naturally.

    I'm not going to delete the valve on mine, as there's no need. I've just ordered a new check valve and hose from Audi, and I'm going to fit an aftermarket check valve inline before the PCV valve too, just to be 100% sure it's leak free
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  18. 1animal1
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    1animal1 The Clar!! it mouves!!! VCDS Map User

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    [Nov 24, 2009]
    i thought the idea was for it to fully breath back into the TIP.... whereas IIRC other 1.8T's have breather filters..... wouldnt this reduce pressure and potentially be a tiny leak/weak point of the system...as opposed to fully breathing via a closed catch tank back into the TIP
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  19. Prawn
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    Prawn My other car is a MINI!!!!

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    [Nov 24, 2009]
    well, the whole idea of the pcv valve and the inlet connection is to use vacuum from the inlet to draw the gasses out of the crank case. as my vacuum pipe is split, the system hasn't been recieving any vacuum in a while, so i guess it can't hurt to just plug up the hole in the inlet for now, and see if it improves performance!

    I'#ll be picking up the new hose from audi tonight though, along with a new check valve to be safe.
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