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134 Fhead Surge While At Idle

Discussion in 'Early CJ5 and CJ6 Tech' started by jeepstar, Aug 8, 2016.

  1. Aug 9, 2016
    ronnie victor

    ronnie victor Member

    raleigh, nc
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    My 1966 cj5 has a PCV. I never knew about it until someone here on the forum months ago guided me to it. One end of the PCV is 'hidden' inside the lower end of a hose that extends downward about 12" from the valve cover to a brass fitting beneath the carb (but on the engine body). The PCV is screwed into the brass fitting. To help identify the brass fitting, there is a thin straw-like rod on the opposite part of the brass fitting, to which connected is a thin hose (I think it goes into the jeep to the heater diaphram (I'll have to check on that tonite).

    In any case, when I realized that there was a PVC hidden in a PVC hose beneath the carb, I pulled it and found much goop to clean out with cleaners. I got the PCV spring inside to bobble around again when shaking the cleaned PCV (before replacing it). If I recall, I got a better idle at that time after the cleaning.

    I can take a pic tonite if you think you need one to examine for PCV location.
     
  2. Aug 9, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Please do
     
  3. Aug 10, 2016
    Stout

    Stout Member

    Quakertown, PA
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    I have a '59 with the original engine (at least I assume it's original) that has a PVC setup.
     
  4. Aug 10, 2016
    ronnie victor

    ronnie victor Member

    raleigh, nc
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    Here's a pic of PCV screwed into brass fitting, just right of center, passenger side of engine.
    IMG_20160810_142740_069.jpg
     
  5. Aug 10, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    20160809_150559.jpg
    Here is my engine. No pcv valve. And yes that is a brand new exhaust manifold already not black. The color peeled off before I even installed it.
     
  6. Aug 10, 2016
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

    Tantallon, Nova...
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    OK, you have what is known as a "draft tube", used before PVC's became the norm.

    Is there a fitting on the intake manifold immediately under your carb where Ronnie's PVC plumbing is connected, & if so what's it running to?

    H.
     
  7. Aug 10, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Passenger side 20160810_151310.jpg
     
  8. Aug 10, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    That looks like the PCV valve. Where does that hose go to? I wonder if that hose is collapsing under vacuum, idle slows hose expands, idle speeds up hose collapses scenario?
     
  9. Aug 10, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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  10. Aug 10, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Watch the engine run and see if the hose is collapsing. If it's not rated for vacuum it can do that.
     
  11. Aug 10, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    The t with the brass plug in is the pcv valve? The hose runs up and connects to the doodad on the top of the motor, just right of center in the pic. Ran it, hose didnt collapse.
     
  12. Aug 10, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    Draft tube is the the tube below and to the left of my manifold in the first pic? It just goes down to the ground.
     
  13. Aug 10, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    The fitting that the hose is connected to, and that screws into that elbow looks like the PCV valve. But looking at it further it may be just a fitting with a hex on it for tightening.
     
  14. Aug 10, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Yes that is the draft tube.
     
  15. Aug 10, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    As much as i appreciate the immediate response and help, today is my anniversary. If i dont get to showering and taking my honeybuns somewhere nice, and soon, she will probably tell me to stay out in the shed. Until we meet again friends!:D
     
  16. Aug 10, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Can you squeeze the hose while it's running to see if that stops the surge? Either by hand or with pliers?
     
  17. Aug 10, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Well, I suppose you'd best keep her happy. :)
     
  18. Aug 10, 2016
    ronnie victor

    ronnie victor Member

    raleigh, nc
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    Jeepstar... you definitely have a PCV valve. Vertical piece in your passenger side pic. Remove the hose clamp, the hose, unscrew the valve, and clean it.
     
  19. Aug 11, 2016
    jeepstar

    jeepstar Well-Known Member 2020 Sponsor

    Sheboygan
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    I have a pcv valve and a draft tube? why the system redundancy?
     
  20. Aug 11, 2016
    Vanguard

    Vanguard Chief Cook and Bottlewasher Staff Member

    Vista, CA USA
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    Your pic showed the driver's side of the engine. PCV is on the passenger side. Post up a pic of that side.

    It was stock on the F134 even on very early engines. Originally added for water fording, not emissions.
     

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