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Small Plastic Valve Thing

Discussion in 'A4/S4 forum(B5 Chassis)' started by NineNails, Sep 4, 2012.

  1. NineNails
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    NineNails Proud sponsor of the snack food industry

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    There's one of those plastic disc shaped valves that is connected at the back of the inlet manifold and runs to the master cylinder and a vac line off to the intake pipe somewhere. What's this valve so I can find one somewhere? I just snapped the nipple off for the vac line. I've kind of super glued it back on but I doubt it will last long.
    Thanks as always
    Si
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  2. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Check valve (one way valve) !
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  3. NineNails
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    Cheers Bradderz. I can't get a repair to hold and I can't get hold of a new valve just now. The small vac line won't attach now and the valve is sucking in air where the nipple snapped off. Car seems to be running ok. Is any harm being done for now? What do those particular vac lines do?
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Just wrap some electrical tape round it for now, to limit the leak.

    That valve stops boost reaching the brake servo. Theres not normally anything attached to the nipple as standard though? I connected my boost guage to it.

    Under vacuum it will draw air in and mess up the fuelling, and under boost it'll leak boost. If you tape it up it'll at least hold under vacuum.
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  5. NineNails
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    Hmmm, that's odd about the small vac line then, I'd not realised it wasn't standard issue. It runs accross the fire wall and then changes to a small bore metal pipe over the cat area and along under the airbox to avoid heat from the cat and turbo I guess then changes back into grey vac hose and disappears under the intake pipe somewhere. I can't remember what it connects to but will have look when I get chance. I kind of realised after my other post that I've induced an air leak so have taped it up like you suggested Kev.
    Cheers for the pointers.
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  6. NineNails
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    Found that this odd vac line goes to the N75 valve. Where should the N75 get it's vac from?.
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  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    nope!

    N75 has three ports.

    One goes directly into the TIP, one goes to the actuator and one goes to the compressor housing on the turbo.
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  8. NineNails
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    I've kind of accidentally overlapped threads Kev, see here for a couple of pics http://www.audi-sport.net/vb/a4-s4-forum-b5-chassis/167904-more-problems.html
    That odd line deffo runs to the N75. I googled some random pics and yes it seems that it should have a banjo on the end of the grey pipe and be connected to the turbo as you say but it just isn't. Wtf is going on here then I wonder? I'm not sure there is even anywhere on the turbo to connect it??
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    non-standard turbo then?

    The turbo should have a banjo like this:

    http://www.hstuning.com/images/stories/hst_frankenturbof4l.jpg

    Which goes to the side port on the N75. The top port goes to the actuator.

    I presume your turbo doesnt have the banjo, so someones tapped a boost feed from the aforementioned nipple?

    If so that begs the question what turbo is it?

    Also not sure how taking a boost feed for the N75 to a post throttle location would work. Its not really supposed to do that i dont think.
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  10. NineNails
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    I really need to get a good look at the turbo then but I'm almost sure there is no banjo on it. All has seemed fine with the motor though, boosts to 12psi etc. Remember it had that chipped ecu in it that caused all those probs last year with dry joints? Mark fixed it for me but I never put it back in. I wasn't told it had been chipped when I bought it so I wonder if it has a different turbo too.
    Ok, suppose there is no where for the N75 to connect to the turbo, is there a more suitable way of connecting it than the way it is just now? Sorry for all the questions but I'm clueless with this.
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  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Well the way its connected ATM isnt really correct, as its sampling boost after the throttle plate. You really need a pre-throttle sense line.

    If there is no tap on the turbo, then you either need to make one (drill/tap the housing etc) or use a fitting that goes into one of the boost hoses, like this:

    8mm Self Sealing Hose Outlet from Merlin Motorsport
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  12. NineNails
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    Thanks for that link Kev. That seems a lot easier and less scary than drilling holes in the turbo.
    Last edited: Sep 12, 2012
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  13. NineNails
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    Been thinking about the plumbing of the N75. Going from what you've said Kev and from doing a bit of googling, I can see how the N75 would still regulate the wastegate the way it's plumbed just now but maybe at a lower level because it is regulating the boost in the intake manifold rather than the compressor housing. In a perverse kind of way is this not better? In the same way we monitor our boost gauge that's tapped into intake manni.
    I'll try a tap into the charge pipe then as close to the housing as poss. Does anyone think I will notice much difference or is my thinking on all this total toss?
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  14. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    The issue, is the N75/wastegate etc is never exposed to vacuum in the normal installation. Vacuum only exists after the throttle.

    Also, it will take longer to respond, as theres much more pipe between the boost source and the N75.

    It may well be you'll notice no difference, i dont know.

    I'd be more intrigued as to why its been done in the first place.
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  15. NineNails
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    Yeah I am Kev. Hope it's not like that to mask some kind of problem with the turbo, just can't fathom it mate. Got hold of a new water pump today so I'll have a good poke about when I fit that. I'll post back the findings. Cheers for the advice as usual pal
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  16. NineNails
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    Ok so the reason there was nothing connected from the compressor housing banjo to the N75 is because....

    [​IMG]

    There's nothing there!!! just an empty hole. I don't know why, maybe the threads are knackered, dunno.
    I was going to temporarily screw a bolt in to block the hole but I couldn't find one to fit. I want to try a proper Banjo bolt and banjo but I need confirmation of the size if anyone knows???
    Is it an M12 like this one 12MM BANJO FOR 8MM HOSE M12x1.5 BOLT FUEL OIL IN PLATED STEEL | eBay
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  17. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    That be a fairly big boost leak then!

    Hmm, no tag on the turbo either, i'm wondering if its been tweaked, the compressor shroud looks thinner than normal...
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  18. NineNails
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    Cheers Kev. By shroud I take that to mean the hole the TIP clamps to. I've just googled some pics of K03's and mine does seem a little different. Standard seems to be a straight hole, where as mine has a slight outward taper. Is this a common/useful mod with any gains to be had? I still need to get a bolt in that hole asap though so still need some confirmation of the bolt size. I'm still thinking M12
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  19. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Well it suggests its been machined out for a larger wheel? Ie its some sort of hybrid.

    No idea on the thread, its very fine though. I'll try and measure it later.
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  20. NineNails
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    Thanks Kev that would be a great help. I've tried googling the banjo size but it's been a bit inconclusive. I suppose this turbo may have been modified hence the chipped ecu I have. Although why the turbo was put back on minus the banjo is a mystery. Perhaps it was supplied back to the owner without it and they just didn't know any better and threw it back on. I've no history of any of this when I got the car. All quite a revelation is this. Dunno if it's a good or a bad thing lol
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  21. NineNails
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    Any luck with that Banjo bolt size Kev?.... Anyone??
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  22. NineNails
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    Err, How many fins should the K03 compressor have?
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  23. olds_kool
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    olds_kool Active Member

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    theres a comparison pic here

    AudiWorld Tech Articles

    my k04 has a single big 'k' on housing same as yours in pic k03 i took off had 3 little 'k's
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  24. NineNails
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    That's a great link, cheers! Well it looks like Kev's right again. I've been googling until my brain was starting to fry. As confirmed in the link above, it seems the K03 has 12 fins... My compressor has 8 fins.
    I was wondering about the single K in the triangle too. However I've looked up the number on the housing 5304 101 50 95B and I get K03 housing. Sooo it looks like a hybrid as Kev thought. K04 compressor in machined K03 housing??
    If someone went to the trouble of doing this (plus chipped ecu) why is the banjo missing and N75 plumbed up all wrong with an intentional bodge??
    This thread seems to have taken an odd turn now lol and I may have to change my sig!
    I'm of mixed emotions now coz half of me wants to get it plumbed up right and throw the chipped ecu back in ans see what's what and the other half is a bit pee'd off coz I doubt I would have bought the car if I had been told it had been modded.

    Any thoughts on this turbo mod, good/bad? All opinions gratefully received. The annoying thing is I have absolutely zero info on who modded the turbo or chipped the ecu

    I think the Banjo is 8mm x 1.0 so I'll take a punt on that, only a couple of quid.
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