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Excess pressure in rocker cover

Discussion in 'A4/S4 forum(B5 Chassis)' started by tonya4, Sep 26, 2010.

  1. tonya4
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    tonya4 TDi Powerrrr

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    [Sep 26, 2010]
    hi,I have excess pressure in the rocker cover of my 2001 facelift 1.9 TDi.I'm thinking it might be worn rings,the mmileage is uite high at 246,000.Is there anything else I should look at?The pressure is so high that it is lifting the oil filler cap and allowing oil to escape.
    I notice there is a pipe from the rocker cover to near the turbo(maybe the egr valve?)

    thanks in advance
    tony
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  3. Oranoco
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    Oranoco Well-Known Member

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    [Sep 26, 2010]
    Strip and clear teh breathers but at that mileage I wouldn't be surprised if you're suffering with ring blow by
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  4. tonya4
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    tonya4 TDi Powerrrr

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    [Sep 26, 2010]
    thanks for the reply

    any ideas where the breathers are?am new to diesel power and still trying to work out where things are

    tony
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  5. Oranoco
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    Oranoco Well-Known Member

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    [Sep 26, 2010]
    Sorry, have to admit I'm too offay with diesel motors, sure one of the chaps on here will be able to advise though
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  6. evilscotsman
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    evilscotsman Space Cowboy

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    [Sep 26, 2010]
    top o the motor mate, theres a big black plastic round bit, thats the pcv valve (positive crankcase vent) that leads to the intake. The valve itself must be blocked, its filled with steel mesh and gubbins but easy changed, just 2 hose clips. its pancake shaped, seen here on a golf engine but same thing. They called it a ccv valve here (lol) but its item 7 - well the thing at the end of the pipe that arrow 7 points too...

    [​IMG]
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  7. tonya4
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    tonya4 TDi Powerrrr

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    [Sep 26, 2010]
    thanks for the replies

    I have seen the bit you are on about,will have a proper look tomorrow

    tony
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  8. evilscotsman
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    evilscotsman Space Cowboy

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    [Sep 26, 2010]
    even disconnecting it will stop the pressure till you get another one, will just smell a bit oily. If it blows oil out under boost after that, then the turbo bearing would have to be leaking from the pressure side into the crankcase but thats less likely.
    Last edited: Sep 26, 2010
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  9. tonya4
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    tonya4 TDi Powerrrr

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    [Sep 26, 2010]
    cheers,will take it apart tomorrow and report back on whats happening

    tony
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  10. tonya4
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    tonya4 TDi Powerrrr

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    [Sep 27, 2010]
    update

    couldn't get the rocker cover off because the inlet manifold is blocking access to one bolt.I removed the breather tpipe and nothing is coming out,so it would appear the filter in the rocker cover is blocked.Am going to see a mate who owns a garage and see if he has a solution to getting the rocker cover off without the need to remove the inlet manifold.

    tony
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  11. evilscotsman
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    evilscotsman Space Cowboy

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    [Sep 27, 2010]
    I think the filter pulls up out of the hole without taking the cover off but may be wrong, tho they usually do.
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  12. jcb
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    jcb Active Member VCDS Map User

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    [Sep 27, 2010]
    PCV = Pressure control Valve IIRC but you may have a number of issues.
    if it has the pressure to lift the oil filler cap (a lot I would have thought!) and doesnt have the pressure in the crankcase/sump to push the dip stick out I would guess that it is originating in the head as much as it may be ring blow by.

    does it smoke at all on overun?
    drink oil at all?
    I would be looking at valve stem seals as well, as you can pressurise the rover cover through blown inlet valve seals but you would still see the oil consumption with the usual issues.
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  13. tonya4
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    tonya4 TDi Powerrrr

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    [Sep 27, 2010]
    it hasn't got the pressure to lift the dipstick.As far as I know it doesn't smoke on overun,and doesn't seem to drink any oil,just leak it out the oil filler cap.

    tony
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  14. evilscotsman
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    evilscotsman Space Cowboy

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    [Sep 28, 2010]
    pcv = positive crankcase ventilation
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  15. alex-qts
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    alex-qts Member

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    [Sep 28, 2010]
    i have a similar issue on my 2000 1.8qts, it doesn't have the power to lift the dipstick but if you take off the filler cap there is alot of preassure under, the car is also smoking (blue) while driving off (not under WOT) the turbo and oil feed lines have been replaced so dont think its that but i am preparing for some engine work!

    what does this sound like?

    would a faulty PCV cause smoking, I am thinking it is the rings as its done quite a few miles!!
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  16. evilscotsman
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    evilscotsman Space Cowboy

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    [Sep 29, 2010]
    no the pcv feeds oily vapour / air into the intake, but not that much, and if it blocks, the pressure can blow external oil seals but cant cause smoking.

    more likely your rings are worn and the oil is getting past into the cylinders directly from the sump. A leaking turbo bearing can inject oil into the intake too and this also causes smoking.
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  17. alex-qts
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    alex-qts Member

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    [Sep 29, 2010]
    I think it must be the rings because it was smoking like this before and after the turbo replace - im just praying its not the turbo really!! I have never done any proper motor work before but the car is garraged now, is it engine out to do the rings?

    I am thinking of going BT at some point, but want to get the motor sorted first, I suppose a compression test will tell me more about the general health of the engine! I need an excuse for that nice big V8 that I cant fit lol

    Thanks for your help!
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  18. evilscotsman
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    evilscotsman Space Cowboy

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    [Sep 29, 2010]
    no probs alex, yeah its an engine tear-down to replace the rings, and while its out you would do the tb, water pump, any gaskets and seals etc then theres the clutch if its not new, especially for big turbo power, standard clutches get fried lol but obv not necessary when repairing the rings.

    Turbo cars suffer from blow-by crank case pressure worse than na's due to the higher cylinder pressures etc when the rings are worn..
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  19. jcb
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    jcb Active Member VCDS Map User

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    [Sep 29, 2010]
    at a push you can do rings with head off engine in, but to be honest if you are doing that much you may as well pull it and do some little things that you wouldn't otherwise do.

    why dont you do a leakdown and compression test with and without some oil/deisel in the cylinder (oil seals the leaking rings partially). would confirm or deny your suspicions before you start pulling engines out.
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  20. alex-qts
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    alex-qts Member

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    [Sep 30, 2010]
    i am currently at uni in southampton and the car is back in london, as soon as i am back i will try to do the compression tests, i have never pulled an engine before so this may be interesting! the most i have done is fitted a new radiator and turbo pipes, could you recomend anyone who would recon the engine for a good price?!
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