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Thread: check valve 2.0 16v 9A

  1. #1

    check valve 2.0 16v 9A

    Hey guys!

    I have a problem with a vacuum leak on my 2.0 9A and when checking the vacuum hoses diagram I noticed that I am missing the check valve all together.

    There is just a hole to where the check valve hose should be.

    Could this be the reason why I have a high idle (1200rpm constantly and with no fluctuations)?

    2019-03-13_100434.jpg
    VW CORRADO 2.0 16v 9A

  2. #2
    ⋆⋆ CF Member ⋆⋆ vw rule's Avatar
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    Hello there,

    I believe the euro spec or USA spec Corrado / Golf 16v engines had a EGR valve (n.o 28 and was bolted to the back of the inlet manifold, but all UK spec 16v engines as far as I'm aware don't have one, but you can sometimes see the moulded recess where the EGR valve would've gone.

    (N.0 11) In your photo is of the vacuum one way valve, that is fitted into the brake servo vacuum pipe, this reinforced plastic pipe runs from the brake servo to the back right of the inlet manifold.
    The 90 degree rubber hose (n.o 13) fits over a steel nozzle end, sticking out of the inlet manifold.
    If the servo pipe wasn't attached to your inlet manifold, then the engine would not start or it would run really badly and just cut out.

    Sometimes the steel nozzle end sticking out of the inlet manifold, can corrode and shear off leaving a hole, but you would hear a massive suction sound as the cylinders are sucking in air, plus the engine wouldn't run for long it would normally try to cut out.

    Idle control valve can play up causing erratic idle and engine cutting out.

    Brake servo pipe can split or the one way valve can split or fall apart, there should also be vacuum hose/s attached to the one way valve, again these can split or fall off.
    There should be 2 or 3 vacuum hoses attached or if only 2 then there should be a small green plug to seal up the none used 3rd vacuum inlet.

    Inlet manifold gaskets can leak as the manifold is in two half's, the 1.8 16v uses 50mm manifold with matching gaskets, and the 2.0 16v uses 42mm manifold with matching gaskets as standard.

    Throttle body gaskets can leak but it is rare.

    There should be a vacuum hose / pipe attached to the throttle body as well.

    The 45 degree inlet hose attached to front of throttle body can split, plus there should be 2 vacuum hoses attached to the underside of that 45 degree inlet hose.

    The large dome inlet boot on top of the fuel metering head can split also.

    Also if you spray some brake cleaner or carb cleaner or WD40 (remember to be careful of the exhaust manifold) if there is a vacuum leak the engine will change note, it'll normally try and speed up slightly for a few seconds.


    Hope this helps
    Si
    Last edited by vw rule; 16th March 2019 at 9:24 PM.
    Had MK2 Scirocco Scarla 1998 to 2002


    Now have Corrado 2.0 16v since 2002 still got it

  3. #3
    Thanks man, you sure know you're way around a corrado!

  4. #4
    Ok!
    After comparing you're information with my setup I am even more puzzled.
    So I think this is the valve (no. 11)
    53871206_1181450452027956_646525880947965952_n.jpg 54518864_826276504392914_5343306299704606720_n.jpg

    One hose (the 90 degree one) is there. The blue silicone hose is probably the EGR one (which is blocked with a screw). The second one goes goes the intake.
    Now, the valve on my car does not seem to have a plug for the hose that goes to the brake servo.

    Does this make any sense?
    Last edited by baff; 19th March 2019 at 3:46 PM.
    VW CORRADO 2.0 16v 9A

  5. #5
    ⋆⋆ CF Member ⋆⋆ vw rule's Avatar
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    Hi at the moment I'm snowed under with work until about 6pm,
    erm are you on WhatsApp if so send me some photos, and then I'll be able to look at things in greater detail.

    I've just sent you a PM reply regarding WhatsApp.

    Si
    Had MK2 Scirocco Scarla 1998 to 2002


    Now have Corrado 2.0 16v since 2002 still got it

  6. #6
    ⋆⋆ CF Member ⋆⋆ vw rule's Avatar
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    Right I've been reading through the 2.0 16v workshop manual for this engine,
    it looks to me as if someone has tried to make up a pipe vacuum adapter connection or something, because the brake servo vacuum assist plastic pipe, should run from the brake servo to the back left of inlet manifold.

    In your second photo above the blue vacuum hose like you say has been plugged off,
    plus the vacuum hose next to it that by the looks of it connects to a white plastic pipe,
    does that white pipe go to the back of your throttle body, or has someone tried to make a brake servo vacuum assist pipe to the brake servo, as the original servo pipe was split or damaged ??

    The white plastic vacuum pipe I think normally runs from the throttle body to a solenoid valve on the back of the air filter box, then from there should be connected to your fuel vapor canister, which is under your air filter box.

    Also on the standard original brake servo vacuum assist pipe, there should be a one way vacuum valve plumbed into the servo vacuum assist pipe, the pipe runs from the brake servo to the left back of inlet manifold, the pipe should run behind a heat shield which by the looks of it is missing from your bulkhead.
    The one way vacuum valve has 2 or 3 small vacuum inlet pipe nozzles sticking out of it,
    one of the small nozzles is connected to a small white vacuum pipe, that then runs through the bulkhead to the back of your instrument cluster, which I think gives you your MPG reading on your dash.
    The other nozzle is normally plugged off with a small green plug.

    Also there should be two support brackets on the back of your inlet manifold. In your left photo above you've circled a small area in red,
    can you see a blue coloured bung / plug, it is connected to the emissions test pipe, which should be bolted upright to one of the inlet manifold support brackets.

    Si
    Had MK2 Scirocco Scarla 1998 to 2002


    Now have Corrado 2.0 16v since 2002 still got it

  7. #7
    ⋆⋆ CF Member ⋆⋆ vw rule's Avatar
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    Quote Originally Posted by vw rule View Post
    The white plastic vacuum pipe I think normally runs from the throttle body to a solenoid valve on the back of the air filter box, then from there should be connected to your fuel vapor canister, which is under your air filter box.

    Si
    Oh hang on I can see the big black vacuum hose is connected to the back of your throttle body,
    that's the one actually I think that runs to the solenoid valve then to your fuel vapor canister.

    Si
    Last edited by vw rule; 19th March 2019 at 10:09 PM.
    Had MK2 Scirocco Scarla 1998 to 2002


    Now have Corrado 2.0 16v since 2002 still got it

  8. #8
    You are right regarding the white hose that goes to the throttle body. Actually that is the only thing that makes sense.
    The blue hose is probably form the EGR which is more likely deleted. That is why is blocked.
    I do have the blue plug on the emission test pipe

    What amazes me is that I am missing the brake servo vacuum hose. I now that this my sound silly but I can't find the brake servo. Isn't it supposed to be behind the ABS pump?

    Can somebody tell me where is the brake servo located on the car (bare in mind that my corrso is LHD) ?
    Last edited by baff; 20th March 2019 at 9:57 AM.
    VW CORRADO 2.0 16v 9A

  9. #9
    ⋆⋆ CF Member ⋆⋆ easypops's Avatar
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    The engine bay side of the brake pedal
    95 Classic Green Storm
    95 Flash Red VR6


    For those who understand, no explanation is needed.
    For those who do not understand, no explanation is possible

  10. #10
    I looked and I just can't find it. I now that this must sound silly. I mean, it's a huge disc shaped black metal thing how hard could it be to spot . But I just can't find it...
    Does anyone have a pic or be more specific?
    VW CORRADO 2.0 16v 9A

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