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308 QV PCV valve

Discussion in 'Technical Q&A' started by spang308, Sep 15, 2005.

  1. spang308

    spang308 Formula Junior

    Jul 17, 2004
    887
    York, PA
    Does the 1984 U.S. 308 QV have a PCV valve, and if so, does it cross over to any other vehicles?

    Thanks,
    John
     
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  3. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,925
    Texas
    Full Name:
    Steve Magnusson
    I don't believe a 308QV has one -- in the sense of a "PCV valve" being a check valve in the line running between the outlet from the upper crankcase and the intake plenum that "opens" under low/moderate intake vacuum conditions to allow the vapors into the intake system yet "closes" under very high intake vacuum conditions (to prevent ingesting liquid oil). See page 77 in your 307/84 OM -- I think that shows all of the components associated with the "crankcase emisson control" system.

    Do you have a specific component on your 308QV that you need to replace, but can't identify?
     
  4. spang308

    spang308 Formula Junior

    Jul 17, 2004
    887
    York, PA
    No. My car is at a friend's shop to have the K-Jet set-up and he told me he thinks the PCV valve seems like it's clogged. i.e. blew the dipstick out of tube when revved, running fat even though the CIS pressures are fine, lopey idle. I don't have the car or the owners manual in front of me. The only crank case ventilation I can remember off the top of my head is the connecting pipe between the two cam covers on the drivers side. I know that pipe T's into something, I just don't remeber what (PCV Valve??)

    In any event, the car has high crank case pressures and runs like crap with good compression and leak down (165PSI +/- in all cylinders).

    Any ideas?

    Thanks,
    John
     
  5. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,925
    Texas
    Full Name:
    Steve Magnusson
    #4 Steve Magnusson, Sep 15, 2005
    Last edited by a moderator: Sep 7, 2017
    With that symptom, I think you should ensure that Item D (the "Oil drop vapour separator"), as shown in Fig 68 on page 77, is not blocked up internally (and, of course, that the interconnecting lines aren't kinked/blocked).

    If you pull the line "B" from the intake plenum (and block off the opening on the intake plenum) and remove the dipstick, and more crankcase vapour comes out the dipstick tube than the line "B" when running, this would be a clear sign that you've got a blockage somewhere.

    Good hunting...
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  6. spang308

    spang308 Formula Junior

    Jul 17, 2004
    887
    York, PA
    Thanks,
    John
     
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