Chris NottMonster Motorsport
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  1. #1
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    Anyone tried deleting the PCV check valve??

    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)







    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 ). 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. #2
    Prawn's Avatar
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    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. #3
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    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?

  5. #4
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    Quote Originally Posted by Prawn View Post
    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.
    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?

  6. #5
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    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?
    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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    There is an interesting thread on ukmkivs about boost leaks from the pcv and one guys thinks is the rocker cover on his agu.

  8. #7
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    Do you have a link to the thread?

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    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.

  10. #9
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    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. #10
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    Hope you get it sorted now mate.

  12. #11
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    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. #12
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    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. #13
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    All the sc.net guys get rid of the mushroom valve and just replace with a 90' elbow.

  15. #14
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    yup and plumb in a catch tank like yours yeah?
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  16. #15
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    Yup, by the way mine does work tim

  17. #16
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    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. #17
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    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. #18
    Prawn's Avatar
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    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.
    -------------------------------------------------------------------------------------------------

    Prawns TFSI Turbo'd 1.8T Track Car

    But I know nothing so ignore me.

 

 

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