1st Gen R53 Cooper S A Look at Tomorrow's Head Problem Today

Discussion in '1st Generation: 2002–06 R50, R53 & 2004–08 R52' started by mini_racer, Nov 19, 2012.

  1. mini_racer

    mini_racer Well-Known Member

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    #1 mini_racer, Nov 19, 2012
    Last edited: Nov 19, 2012
    So, I change my spark plugs often, roughly every year whether I think they need it or not. I do some things preventatively and while you can't exactly call it cheap insurance for a set of good plugs, it still is insurance.
    Anyway, it is about that time again and I wanted to share a little concerning reading the old plugs.

    This is a pic of the business end of my plugs and it looks OK, maybe slightly on the darker side with a small amount of carbon, but not too bad. And they are definitely not too tan, indicating too lean or too hot. They are in order here 4-3-2-1, from left to right.
    ImageUploadedByTapatalk1353337830.374023.jpg

    One thing that does not look quite right is above the plug seating surface on 2-4, lets look at the top side of the plugs better. Of course the order here is reversed and 1-2-3-4.

    My next post will have this next pic and some further discussion because the mobile app I am using has some limitations...
     
  2. mini_racer

    mini_racer Well-Known Member

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    Ok here is the pic of the topside of the plugs and again the order is 1-2-3-4:
    ImageUploadedByTapatalk1353342112.995645.jpg

    Note the black carbon deposits above the plug seating surface on plugs 2-4. It is limited by the boot fitting snugly around the insulator about halfway up. Look at plug #1 above the gasket, they should all look like that, perfectly clean.
    Carbon deposits above the seating surface means that the plug was not tight enough and combustion gasses were blowing-by the gasket/seat. This is...... uh...... bad. The terminal nuts were also loose on those plugs and they did not require a ratchet wrench to remove, they were essentially loose. The terminal nuts were likewise loose on those 3 plugs.

    Today the problem is minor, maybe a little performance/ efficiency loss. Left alone the plug would have just kept getting more loose until it starts throwing codes and/or one of them gets blown out of the head.

    The warning is to check those spark plugs. When installed these were torqued to 20ft-lbs as per spec, somehow that was not sufficient to keep them seated properly. Checking them is not really hard and something I should have done more often.

    With a crush gasket style of plug, the plug manufacturer will typically indicate an installation torque or tightness of 1/2 to 2/3 of an additional turn after the gasket touches the seating surface on the head. Using a torque wrench you will hit 20lbs before you get to a half turn. So this time I made sure to use a little anti-seize lube and went with the half turn tightness which would be closer to ~25 or maybe even ~30ft-lbs. Still, I think I will check them after they go through a few heat cycles.

    Crisis Averted! :^)
     
  3. k-huevo

    k-huevo Club Coordinator

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    Vehicles used at high performance levels like frequent HPDE participation should have their plugs changed at frequent intervals, nothing wasteful about that; normal street mileage intervals do not apply.

    Light tan is an indicator of correct fuel mixture. These plugs are a tad too cold.
     
  4. mini_racer

    mini_racer Well-Known Member

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    #4 mini_racer, Nov 19, 2012
    Last edited: Nov 19, 2012
    Agree with all points, and good plug read there K. While these are not crazy off and the pics are maybe not as bright as they could be, there is a little too much carbon for my taste as well.

    These plugs are range 8 and I have installed range 7 for this next set. Thanks for the consult Chris at Sneed's.
     
  5. Dave.0

    Dave.0 Helix & RMW Powered
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    I check my plugs 2 times a year and I change them every year about a month before the Dragon. A week or two after I replace them I go back and check the Tq to make sure they did I not loosen up after a few heat cycles.
     
  6. Drillslinger

    Drillslinger New Member

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    To revive an old thread ... GREAT advice here as I recently blew a plug in my R53. New plugs and/or the time to check them is CHEAP compared to rebuilding or replacing a head :-/
     
  7. Crashton

    Crashton Club Coordinator

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    I know of two folks local to me this has happened to. Not fun when this happens. I've never heard of an R56 blowing a plug out. I suppose their held in by all that carbon.

    Thanks for the timely reminder Drillslinger.
     

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