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Do Spark Plugs Wear Out?

Discussion in 'Early CJ5 and CJ6 Tech' started by Buildflycrash, Apr 18, 2022.

  1. Apr 18, 2022
    Buildflycrash

    Buildflycrash More or Less in Line. 2022 Sponsor 2020 Sponsor

    Gulf Breeze FL...
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    I hear that folks replace them? I have 2sets for my jeep (which runs rich) So far I just switch them out. I clean ‘em with a brush and paint thinner, gap and repeat. When do they wear out? How do you know?
    Thanks.
     
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  2. Apr 18, 2022
    scott milliner

    scott milliner Master Fabricator

    Seattle Wa.
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    Try running a V-6 on one bad plug. There's no power at all.
     
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  3. Apr 18, 2022
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    The old-tyme procedure was to sand blast them and reinstall. I suspect they get combustion products baked onto the electrode surface or the ceramic, and the abrasive removes that. Eventually the blasting erodes the conductors and they are really done. Possible solvent will not properly clean them.

    Seems that today they are cheap enough we can afford to throw them away rather than clean them.
     
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  4. Apr 18, 2022
    jeepstar

    jeepstar Well-Known Member 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    My old jeep doesn't run enough to wear them out, but I just replace them every spring, regardless.
     
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  5. Apr 18, 2022
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    I've seen the electrode burned off of spark plugs that weren't changed in who knows how long.
     
  6. Apr 18, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    The electrodes definitely burned away and the gap would open with extended use. That's why we used to check and set the gaps at each service interval. Eventually the electrodes get wore down to nubs.

    Learning that from your Dad was a ritual of growing up. And, servicing your plugs is how your Jeep knows that you love it. :D

    Modern vehicles have done away with frequent service requirements - which I'm sure started as a sales tactic as much as any improved technology. Like removing the grease point from a UJ, and labelling it "lifetime."

    Plus, on many like my Ford truck, my mechanic flat refuses to even touch the spark plugs, they have become so difficult to access, and so likely to fail (strip, blow out, or break). A century of automotive progress. :rolleyes:
     
    Last edited: Apr 18, 2022
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  7. Apr 18, 2022
    Jw60

    Jw60 Airbender and interrupter of the light guard. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    You have a 5.4l do you?
     
    Last edited: Apr 18, 2022
  8. Apr 18, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    How did you guess?

    On my second engine, at 125K. Already blown one plug on engine #2 at 50K. :censored:
     
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  9. Apr 18, 2022
    Jw60

    Jw60 Airbender and interrupter of the light guard. 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    My parents have one, my wife’s parents have one, my wife’s sister has two.
     
  10. Apr 18, 2022
    hooliganrick

    hooliganrick Sponsor

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    remove, wire brush, clean threads, re-gap, and re-install, unless they appear off.
     
  11. Apr 19, 2022
    nickmil

    nickmil In mothballs.

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    Short answer is yes they do. Electrode and ground strap erode over time.
     
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  12. Apr 19, 2022
    Rich M.

    Rich M. Shoe salesman 2022 Sponsor

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    Running rich with efi?
     
  13. Apr 19, 2022
    Buildflycrash

    Buildflycrash More or Less in Line. 2022 Sponsor 2020 Sponsor

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    Not as much for sure.
     
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  14. Apr 19, 2022
    colojeepguy

    colojeepguy Colorado Springs

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  15. Apr 19, 2022
    mickeykelley

    mickeykelley Well-Known Member

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    IMHO that plug in the pic could easily be cleaned and re-gapped.
     
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  16. Apr 19, 2022
    jeepdaddy2000

    jeepdaddy2000 Member

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    Original plugs wear out over time. This is due to the spark taking a minute amount of material off every time it jumps the gap.You pulled the plugs every tune up interval (usually every 3K miles), and inspected/cleaned/regapped them. Newer plugs that run platinum or iridium electrodes don't do that and are good for up to 100K miles.

    If you ever wondered why spark plug gappers use a round wire it is because the wear can come in an arc on the ground electrode.

    Spark plug cleaners/testers used to be a common item in most shops. They were air operated. You cleaned the plug, regapped it, then ran it in the tester to insure it was firing properly.

    There are also12 volt battery powered cleaners. I used to have one in tool kit back when I rode 2 stroke dirt bikes.
     
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  17. Apr 19, 2022
    Twin2

    Twin2 not him 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    HF spark plug blaster . from years ago
    bought it for lawn mower . it liked oil
    spark plug cleaner - Copy.jpg
    now back to question . I only service plug if . I feel a miss
    my new car said to replace plugs at 40K . 4 cylinder turbo
    7 year old car with 20K :shrug:
    last time it was at dealer for oil change . they recommend changing brake fluid
    never heard of such thing
     
  18. Apr 19, 2022
    jackdog

    jackdog Member 2021 Sponsor 2020 Sponsor

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    Try changing plugs in a 3.6 Chrysler TC. You have to remove the intake manifold and everything above it.
     
  19. Apr 19, 2022
    colojeepguy

    colojeepguy Colorado Springs

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    The wear on the center electrode would negate much of the benefit.
     
  20. Apr 19, 2022
    Lockman

    Lockman OK.....Now I Get It . 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    I have a sheet regarding " Reading Spark Plugs " . With HEI diagnostics & regarding Race engines, it's important info, I believe.
    AFAIK, The readings from your O2 sensor being sent to your PCM or ECM is typically why our engines run Rich. Also, the Stoich metered air intake flow is important too.
    Of Course ,this last part does not apply to all systems .
     

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    Last edited: Apr 19, 2022
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