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Thread: VXR / OEM NGK Spark Plug Warning

  
  1. #1
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    2DD - Turbodave's Avatar
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    Cracked insulators on VXR / NGK spark plugs

    Hi Guys

    Now, before we all panic... I'm not looking to create mass hyseria here but I have discovered a slight issue with the plugs fitted to my car and it may be a one off, but it's something that I've never experienced before in all my turbo driving days.

    Basically, fitted a set of GM 'VXR' original spark plugs about a month ago (or about 500 miles) which came in the box branded as NGK PFR6T-G and all was well. To cut a long story short, the car is running FMIC, full exhaust and a pahse one map however since they were fitted I can hand on heart say the care has never seen over 4000rpm... put it this way, I'm averaging 32mpg!

    Tonight, ahead of a remap on Friday I took them out just to double check the gaps and to ensure they were tight etc... in effect, just faffing about.

    This is what I found:





    Ever plug has hairline fractures in two of more areas of the ceramic insulator and number 4 (nearest the battery) has actually fractured a large section off which I did recover before it fell inside the engine thankfully.

    What caused this is beyond me, the car runs at perfect temps and I haven't been thrashing it senseless for the past few miles either. It's had a steady run to Devon and back and the rest has been the daily commute into work.

    Incidentally the car was MOT'd today and failed miserably on emissions, which I put down to the 200cell cat or a mapping/fueling issue. Whether a possible fuellng issue could cause this, if the car is running lean and thus hotter... is beyond my technical abilities but there is obviously some reason this has happened.

    Any suggestions greatly appreciated... although my pressing issue is the car is now strandaed and I'm understandably reluctant to use these plugs even to get to the nearest spark plug shop!

  2. #2
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    Couple of Q's.....

    Has anyone had tyo check the plugs apart from you ?
    (they could have been damaged/swapped by an unruly YTS scamp)

    How is the insulator at the spark end ?

    Does this help:
    http://www.sacskyranch.com/eng217.htm

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    Nope, nobody has been near the car apart from me so they are the ones I fitted and torqued properly (had a plug seize before from being too tight - not funny!) and there is no oil or moisture down the plug holes or anything like that.

    The actual business end of the plugs look perfect, no burning on the tips nor is there any evidence of cracking on the core etc. They are a slight greyish in colour, nowt any differnt from the last set that came out or the plugs in the Cavalier etc.

    My immediate concern is, did any of the fractured ceramic insulator fall inside number 4 cylinder... there was one bit on the edge of the hole which I rescued with a blob of Blu-Tax on a poking device (screwdriver) but the concern I have... it's not a big enough bit to fill the cracked off section of number four plug cermaic.

    So, that means it's gone south... and that doesn't fill me with confidence. Laugh as you might but I've just been out and cobbled together a thin bit pipe onto the end of the hoover attachment and put it down inside the combustion chamber so I can only hope it's sooked up anybit of ceramic that may have fallen inside.

    If it hasn't... anybody know what would happen if a little bit of insulator was inside when it's next restarted or does that not bear thinking about?

    I really am beginning to hate this car...

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    have a look here on this page at the bottom;

    http://www.globaldenso.com/en/produc...ing/index.html

    seems like too much torque has been applied

    i fitted a set of these just this week, so il check the torque tomorrow!


    jimbo
    ASTRA MK4 GSI TURBO
    WAS CS3 268bhp & 282lb/ft
    NOW CS4 279bhp & 336lb/ft

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    Just out of interest mate, what gap did you have on the plugs?

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    Hmmm, well... no aruing with that link but these were definately torqued correctly, if anything I thought they were a bit loose coming out as it took almost no effort with a 3/8th ratchet. I initially thought they were so loose that why it was perhaps running badly unless, once the ceramic cracks it relieves tension or something? I did notice, the plug with the biggest chunk missing has actually distorted which made me think the coil pack had been pulled down too tightly... but that's not possible as the bolts in that were also literally finger tight plus the smallest of tweaks.

    However, the 5th emergency service arrived a few minutes ago in the form of my mate who also brought a set of unknown plugs from his Redtop, ok so not ideal for the Z20LET but it started, sounded a bit clattery (ceramic insulator exiting via the valves?) then cleared itself and idled happily... and yes, these plugs have been put in but again, finger tight and a wee tweak.

  7. #7
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    My machanic mate told me to stay clear of ngk, he said he used to swear by them too.
    ARDEN BLUE GSI

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    only time i have seen plugs go like that is when someone has cracked them fitting/removing them or removing coils or leads from the top of them. its the only way they can crack. if the have been fitted without any damage nothing that can happen in the normal running of the car can cause that to happen.

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    I was going to go for these next after the cossies die off. Might have to rethink. Have never seen a plug do that unless it has been over tightened. Unusual for all 4 to be like that though.

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    It could well have been a faulty set/batch on manufacture,
    In my experience sometimes a new plug can be dead

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