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62' Cj5 Blue Smoke On Acceleration

Discussion in 'Early CJ5 and CJ6 Tech' started by Rogert, Mar 13, 2019.

  1. Mar 13, 2019

    Rogert New Member

    Southern California
    Jan 7, 2019
    I just finished dealing with a carburetor flooding issue which was detailed in an earlier thread here. Now it runs very well but there is a billowing cloud of light blue smoke when I accelerate. I'll list the series of events here, hopefully it will give you all some evidence as to what's going on without too much unnecessary details.

    1. Fixed carburetor flooding issue
    2. Went for a victory drive and it was billowing a lot of light blue smoke (more than now) even at idle
    3. Removed oil plug after victory drive (while warm) and let oil drain for a few hours while I ate spaghetti
    4. Oil smelled like gas
    5. Removed mechanical fuel pump and installed block off plate (electric pump was installed by P.O. who left mechanical pump attached to engine but disconnected the fuel lines)
    6. Plugged vacuum line that ran to fuel pump
    7. Replaced oil filter
    8. Filled engine with 4qts 30wt dinosaur oil and 1qt "Lucas Engine Oil Stop Leak"
    9. Drove it around for ~3 or 4 hours and needed to add 1qt of oil as indicated by my friend the dipstick
    This is where it stand now. The smoke is not noticeable at idle but is a billowing cloud on acceleration, especially if I am going uphill. The smoke is not really that bad on deceleration/when engine braking downhill. It seems to have gotten slightly worse over the past week but that could be all in my head. I did a compression test today while the engine was still decently hot and these are the numbers I got. (test was done by removing one spark plug at a time)

    Cylinder - Without squirt of oil/With squirt of oil

    1 - 90/100
    2 - 93/103
    3 - 93/110
    4 - 90/110

    What I believe happened was that the mechanical fuel pump failed and started leaking fuel into the oil. This prompted the P.O. to install an electric pump but they never replaced the oil. The oil got thinned and when I got it running right was leaking past the rings/valve guides causing the huge amounts of blue smoke initially.

    My questions are these,
    1. Do these compression numbers mean my rings are worn and need to be replaced?
    2. Is it worth looking into the valve guides as the source of the oil or should I go straight for the rings?
    3. Could some of the oil/gas combo have been left in the engine during the change and be causing the current oil to thin and leak into the combustion chamber? (I just smelled the dipstick and it doesn't smell like gas).
    Thanks for all of you help folks I couldn't do this without you.
  2. Mar 13, 2019

    jeepstar Well-Known Member 2021 Sponsor 2020 Sponsor

    Jun 28, 2006
    Head gasket....
  3. Mar 13, 2019

    PeteL If it wasn't for physics, and law enforcement... 2021 Sponsor 2020 Sponsor

    Hills of NH
    Aug 3, 2003
    I have some friends who are dipsticks, too, but I love them anyway - even if they are a quart low. :D

    Those compression numbers are low, but not impossible for a used f-head. I would think a bad head gasket would show as one or two cylinders being different than the average.

    In my personal experience, F-heads have often have broken rings, but again the bad cylinder would probably stand out.

    My '57 burns a lot of oil. (Ask anyone on the trail behind me.) It shows especially on acceleration after a long downhill run, which is likely rings and guides.

    But oil is cheaper than a rebuild.
  4. Mar 13, 2019

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
    Sep 21, 2002
    How soon after shutting it off did you check the oil? 3 or 4 hours of driving and needing a quart isn't really too bad in the scheme of things. I'd try 5 quarts of 15/40 diesel oil and no additive. If you don't have one you need an oil pressure gauge.
  5. Mar 13, 2019

    70cj5134f Member

    East Tn
    Aug 18, 2018
    Got a pressure regulator on the fuel pump?
    Do u have a pcv valve?
    Did it smoke before flooding issue?
  6. Mar 13, 2019
    GTS Dean

    GTS Dean New Member

    Feb 21, 2019
    With your previous flooding issues, it is possible that your cylinder walls were washed clean. The previous oil was probably heavily fuel diluted and not promoting good sealing by the oil control rings. Your fresh oil change should help the walls, and you may need to squirt some more top cylinder treatment in case the compression rings are stuck.
  7. Mar 13, 2019

    Alan28 Well-Known Member 2021 Sponsor 2020 Sponsor

    Ch√Ętillon en...
    Oct 21, 2012
    With a new good oil you can make again the test.
    How is the oil pressure and the temperature after 15 minutes of good driving?
    I have installed oil pressure gauge and temperature gauge on the dash, they are the Willys model.
    Of course if your oil pressure goes down and you temperature goes too high there is a problem.
    But as I understand the problem is elsewhere, with a new oil the test will be better.
  8. Mar 13, 2019

    NCRenII yellow fever

    Far Nor Cal
    Sep 22, 2017
    I'd try two things:

    1) endoscope (fits to android phone or p.c.) to inspect cylinder walls through a spark plug hole
    2) while the spark plugs are out (and if no severe scuffing apparent) squirt in some marvel mystery oil, then add some to the fuel tank and the crankcase.
    Run for awhile. The stuff is known to clean and free up piston rings and cleans guides, seals and gallerys.
    After running change oil and filters (cut open the filter for kicks). See if it helps.
  9. Mar 13, 2019

    Keys5a Sponsor

    Florida Keys
    Jan 23, 2014
    Blue smoke is oil burning. Pull the spark plugs and inspect them. Are they all equally oily? If one or two stand out as worse than the others, you likely have broken rings or cracked ring lands on the piston.
    Try running a heavier weight oil, at least 30w.
    You could have really bad valve guides on the intake valves, allowing oil to be pulled into the combustion chamber.
  10. Mar 13, 2019

    70cj5134f Member

    East Tn
    Aug 18, 2018
    Add a bottle of witch oil,(no smoke, motor honey, stp for high mileage)?
    Mine smoked bad until I got the pcv straightened out?

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