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Pcv Questions

Discussion in 'Early CJ5 and CJ6 Tech' started by Kene', Dec 8, 2018.

  1. Kene'

    Kene' New Member

    Bought a '63 CJ5 with the 134F it had no PCV. The valve cover cap where these mount was just left open. There was no hose on the dip stick to breather tube. I installed the hose and plugged the cap to keep contamination out thinking the breather would provide enough ventilation. I am now rethinking this. Questions:
    1. Is the dip stick to breather hose enough ventilation?
    2. Did any of the 134F come without PCV?
    3. How do I tell if it is a closed system? Apparently the PCVs are different.
    4. If I install one, does it have to route into the Carb/intake? I really don't want to mess up the air/fuel mixture.
    5. Does it need to be one of the $40+ units or will one of the $10 generic alternatives work?
     
    Kene', Dec 8, 2018
    #1
  2. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    #2 - yes some of the early trucks for sure, maybe others.

    The PCV was developed for the military jeeps to operate underwater.
     
    PeteL, Dec 8, 2018
    #2
  3. 70cj5134f

    70cj5134f Member

    I made one with a couple different size hoses and a cheap pcv valve.
    20180824_201606.jpg
     
    70cj5134f, Dec 9, 2018
    #3
    Kene' likes this.
  4. Kene'

    Kene' New Member

    I was thinking on that line. Mine does not have the valve cover breather, it comes off the side of the dipstick tube.
     
    Kene', Dec 9, 2018
    #4
  5. 70cj5134f

    70cj5134f Member

    I've benn told my valve cover came off another jeep?
    I've got the dip tube hooked to air filter.
    Any internal path is ok, positive crankcase ventilation.
    Mine would not run right until I hooked it up?
    Ok to use the dip tube to intake vacume.
     
    70cj5134f, Dec 9, 2018
    #5
    timgr likes this.
  6. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Yep, all you have to do is connect the crankcase to engine vacuum with a valve between, and plug the draft tube. You may want to arrange something to catch any atomized oil in the vapors - some cars (Volvos?) have sort of a drool bucket between the crankcase and engine vacuum. You can make one with a can and a couple of copper scrubbies.
     
    timgr, Dec 9, 2018
    #6
    J walk likes this.
  7. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    There were three different systems used for CC ventilation:

    -A draft tube with no pcv valve and a ventilator filter mounted to the top valve cover which was used on trucks & early CJ2's​

    -A pcv valve mounted to the side valve cover & plumbed via a 3/16" steel tube around the front of the engine into a vacuum port on the manifold under the carb with a fresh air feed from the air cleaner to the dipstick tube​

    -A late model system that has a combination vent/pvc feed mounted to the top valve cover with a rubber hose the runs to a pcv valve that attaches to the vacuum port under the carb.
    ​
    Note that the early system and late uystem ventialator filters look very similar, the difference is that the early one doesn't have a hose barb.

    Per the parts manual for your '66 you should have side mounted pcv with the vented dip stick tube.
     
    Last edited: Dec 9, 2018
    Howard Eisenhauer, Dec 9, 2018
    #7
  8. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Reading Howard's post, I forgot to mention that you need a fresh air intake to the crankcase. On most cars this comes from the air cleaner. Filtered air comes in to the crankcase, mixes with the crankcase vapors, and exits through the intake manifold.
     
    timgr, Dec 9, 2018
    #8
  9. baldjosh

    baldjosh Member

    I was recently noodling this and came to the conclusion that the tube tees at front of block and goes to both the vacuum pump (if there) and manifold...
     
    baldjosh, Dec 9, 2018
    #9
  10. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    You is correct Sir.
     
    Howard Eisenhauer, Dec 9, 2018
    #10
  11. Kene'

    Kene' New Member

    Mine had the second version, but someone removed the PCV and the breather hose, leaving both open to atmosphere. I guess I will set it up as original and hope it doesn't disrupt my carb air/fuel mixture too much.
     
    Kene', Dec 9, 2018
    #11