HT0 spark plug bottom strap failure.

Discussion in '2005+ Mustang GT 4.6L Tech' started by DETROIT, Jan 2, 2020.

  1. DETROIT

    DETROIT Junior Member

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    Have any of you guys seen a bottom strap separate from the plug like this? This was cylinder #8 and I have 5000 miles on this plug.

    06 GT with a KB at 10lbs. I was driving normal during failure.

    [​IMG]


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  2. 06 T-RED S/C GT

    06 T-RED S/C GT forum member

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    Never seen nor heard of a ground strap separate from a plug like you've posted here. In fact, I've been running Autolite HT0 plugs on my supercharged "06" GT w/Saleen VI S/C and never had any issues with them, but then again, my car's max boost is rated at 7.5lbs. with 3.6" pulley. However, if the Autolite plug that separated is 5 years old and under? it's covered under Autolite's manufacturer warranty policy. Therefore you may want to contact Autolite and find out if they'll replace the plug under warranty :shrug:
     
  3. RED09GT

    RED09GT Senior Member S197 Team Member

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    I've seen the groundstrap melt but if this happened during normal driving, I'd say this is a manufacturing defect.
     
  4. 05stroker

    05stroker Never enough power guy!

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    The new design is stupid with the staps being attached afterwards.
     
  5. DETROIT

    DETROIT Junior Member

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    My bore scope arrived today And I was able to get a few pic’s.

    I only see damage to the piston and not the cylinder.

    Question, can I run 2008 heads on this block?
    [​IMG]


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    Last edited: Jan 2, 2020
  6. 06 T-RED S/C GT

    06 T-RED S/C GT forum member

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    Agreed!

    Couldn't agree more! The previous design was much better with the straps directly attached to the electrode shield as an integrated unit.

    Yes, the revised 2008 heads will fit on the 2005-early 2008 3v motors. All that changed was the head design from the 2005-early 2008 models which had the 16mm high-thread 2-piece design spark plugs over to the standard 12mm one-piece design plugs on the revised 2008 3v heads built after November 2007.
     
    Last edited: Jan 2, 2020
  7. Rick Simons

    Rick Simons Junior Member

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    Detonation?
     
  8. RLF9409

    RLF9409 My blood runs Ford blue!

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    Jesus! WTH is going on inside that cylinder??? That piston is done! I am surprised there is no scoring on the cylinder wall...
     
  9. 07 Boss

    07 Boss Senior Member

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    I never liked the strap electrode design. I've always run Brisk plugs. I'm running Accel plugs now. Had HT0's in there once and used to get a bunch of popping and banging under decel and figured the strap design was hindering the combustion process. I still get a little rumble but the popping and banging went away after switching back to a regular type plug.
     
  10. DETROIT

    DETROIT Junior Member

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    Which plugs are you running? I thought the ht0 where the only cold plug I could run in that head.


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  11. 06 T-RED S/C GT

    06 T-RED S/C GT forum member

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    Which Accel plugs are you running? I wasn't aware that Accel made a one degree colder spark plug that also includes a one piece design for the 2005-early 2008 3v cars. I was also under the impression that only HT0 plugs were available in both a platinum and one degree colder spark plug for the "05-early 08" 3v cars :shrug:

    That's exactly what I thought as well :shrug:
     
    Last edited: Jan 3, 2020
  12. 07 Boss

    07 Boss Senior Member

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    https://www.cjponyparts.com/accel-s...colder-16mm-set-3v-4-6l-2005-2008/p/SP8160C1/

    Not sure if they're a 1 piece design but I don't care as I pull, examine and clean my plugs 2-3 times a year.
     
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  13. DETROIT

    DETROIT Junior Member

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    ^^ thank you, I’ll start looking at them. Let me throw this out there.

    500 miles after the plugs were installed my # 1 cylinder had codes for a misfire. I pulled and replaced the plug. Attached is a pic of the #1 and 8 cylinder plugs. It’s making me wonder if something else is going on in the block.


    [​IMG]


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  14. 06 T-RED S/C GT

    06 T-RED S/C GT forum member

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  15. MrBhp

    MrBhp Junior Member

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    I would be less concerned with the plug strap and very concerned with the obvious detonation occurring from a lean condition. Unless I'm seeing it wrong, that piston has already failed. It's going to be catastrophic failure soon. Have you done any data logging recently?
     
  16. DETROIT

    DETROIT Junior Member

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    No I have not, I bought the car used and it had a horrible tune with a lot of detonation at full throttle. I took it to a local speed shop installed new plugs and had them do a safe tune on their dyno. It has ran solid for the past year as my DD, without any a/f alarms.

    I’m thinking the damage was already done. Right now I’ve been talking with a few shops at building this block, if it is still good.

    Any thoughts on creat engines at a fair price?




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  17. 06StangGT

    06StangGT forum member

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    You're going to be better off having a reputable machine shop take your block and make it a 10 or 20 over. (If your block is still good) Then getting some better pistons and rods in there, and having a reputable tuner tune while data logging. The 05+ nemac block is plenty strong.
     
  18. Rick Simons

    Rick Simons Junior Member

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    Yeah after seeing that plug with the strap blown off, I'm going with detonation. It's a very destructive process!
     
  19. 06 T-RED S/C GT

    06 T-RED S/C GT forum member

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    After reading over some of the recent posts, I tend to agree it was detonation which caused the plug strap to blow off rather than from a manufacturer defect with the HT0 spark plug that was previously suspected from a previous post in which I had submitted earlier in the thread.
     
  20. JeremyH

    JeremyH 3V Fuel Guru S197 Team Member

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    Strap issues is the symptom. Root problem was the detonation which will melt and break any plug.

    PSA When you use 16mm autolites be it either ht1 or ht0 get the HSS version that came out in 2010. Vice original version that is still sold.
     
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