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Cj5 Smokes When Revving Engine And When Accelerating.

Discussion in 'Early CJ5 and CJ6 Tech' started by 1957Willys, Sep 25, 2016.

  1. Sep 25, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    My CJ5 starting smoking blue smoke today I noticed it when I cranked it up. The smoke was really bad then it went away. I noticed it smoked alittle when accelerating after I let off the gas to slow down. I let it sit for awhile and cool off I went out and cranked it up a few minutes ago and it smoked blue smoke again. So I have done a search and found that the three common things for a F-134 could be intake valve guides, valve guide seals or rings?
     
  2. Sep 25, 2016
    Stout

    Stout Member

    Quakertown, PA
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    I would guess valves since bad rings. If it were rings, it would probably smoke constantly rather than go away.
     
  3. Sep 25, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    It doesn't smoke at idle.
     
  4. Sep 25, 2016
    PeteL

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

    Hills of NH
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    Maybe check your PCV system, since it seems it came on so sudden.

    Also if you have the combination vacuum/fuel pump, be aware it can communicate a leak to/from the crankcase if a diaphragm is failing.

    How's the oil level?
     
  5. Sep 25, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    I agree with Pete. If it truly came on suddenly then that of course isn't normal. Pull the dipstick and smell for gas would be the first step to take.
     
  6. Sep 25, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    I have a single action fuel pump and I checked the hose coming off the top of the valve cover and there wasn't alot of oil residue.
     
  7. Sep 25, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Single action can definitely leak gas into the oil. Smoking when revving usually indicates oil rings tired.
     
  8. Sep 25, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    I sure hope not I have been doing some research on how the valve stems are sealed. So the intake valve has a oring and the exhaust doesn't? How does the oring seal? I'm used to small blocks with press on valve stem seals.
     
  9. Sep 25, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Since the exhaust valve is in the block it doesn't need a seal. I've never messed with valve guides myself, I had the machine shop install them and assemble the head.
     
  10. Sep 25, 2016
    PeteL

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

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    Okay, but what about the PCV valve on the side cover??
     
  11. Sep 25, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    Mine is on the side of the cylinder head under the carburetor with a rubber hose that runs up the to valve cover. The side cover has a larger fender washer over it like in the pictures. CouvillonEngine.jpg
     
  12. Sep 26, 2016
    PeteL

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

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    Okay - not like my stock original '57.
     
  13. Sep 26, 2016
    Chilly

    Chilly Active Member

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    Concur with theory that a sudden onset of blue smoke likely isnt ring wear. Good advice on PCV and valve seals. Dont know what yours look like but the umbrella seals on I6 become brittle, ride up the stem, or fall away in pieces.

    Might also be plugged oil drain-back holes in the head, flooding the top of the head faster than it can drain.
     
  14. Sep 26, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    This isn't the original engine it was replaced at some point in time.
     
  15. Sep 26, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    How long and how much have you been driving it? Any chance it was maybe already lightly smoking and you didn't realize it? Recent oil change?
     
  16. Sep 26, 2016
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Valve seals should smoke most when you back off the throttle, IIRC. Manifold vacuum goes way up, pulling the oil into the cylinders.
     
  17. Sep 26, 2016
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Also smoking on startup after the engine has been sitting a while is a normal scenario.
     
  18. Sep 26, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    I've had it for four years it wasn't running right when I got it. Because the carburetor shaft was worn out and the valve lash was to tight and the oil pump was out of time so the distributor could not be put in time.
     
  19. Sep 26, 2016
    samned

    samned Member

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    I just had a smoking issue with my F 134 . The first thing I did was to check the pct valve. I took it off and checked to make sure it was not stopped up. The next thing was to check the fuel pump. The oil has a slight smell of gasoline so I changed the fuel pump. This slowed the smoking for a brief while, but it then came back. I then did a compression test on the motor to check to see what the general condition of the rings and pistons. All 4 of the cylinders checked out at 120 psi during a dry compression test. I then added a squirt of motor oil to each cylinder and the compression rose to 140 psi on all cylinders. So after dog all of that I took the head off and had it checked by a machine shop. Valve guides checked out ok but valve seals needed replacing . Valve seals were replaced and a head job was done to ensure a good seal. After reinstalling the head I had a slight smoking issue again but it soon disappeared and motor is running great. I would highly recommend a compression test to check the condition of the internal parts of the engine.
     
    Rick Whitson likes this.
  20. Sep 26, 2016
    1957Willys

    1957Willys Member

    Birmingham, Alabama
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    I'm going to pull one of the valve springs off when I get home this afternoon. To see what shape the valve seals are in and to see if there is any slack in the valve guide. I think I'm going to use the string method for keeping the valve up.
     
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