FBO Engine Misfire

Discussion in '2005+ Mustang GT 4.6L Tech' started by Redfire_Jimi, Jun 27, 2022.

  1. whitmanink

    whitmanink Member

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    yea time will tell , either way it sucks it happened,,

    i think the only valve strike is when the little bearing bits slammed into them when they made there way into the cylinder...

    i also find it odd there is not paint marks on the head bolts , to show the 90deg after torq spec,, my paint stayed on ,,

    ,, i think the timing off isnt true,, the one experience ive known when timing jumped,, you knew something was horribly wrong and was throwing codes left and right, and the engine jumped and kicked so hard ,, before it eats itself .. if the pistion hit the valve , than the other bank the same thing should have happend?..

    but i guess theres no use sitting here with tin foil hats on, ,, time will tell the cause for sure
     
  2. whitmanink

    whitmanink Member

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    looking at the pic again,, it looks as tho the keeper is almost off,, the right side isnt touching itself
     
  3. Midlife Crises

    Midlife Crises Senior Member

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    Yep! The piston smacked that valve so hard it destroyed the follower and mangled the valve. That impact and the follower coming apart tore up the cam lobe and some of that trash is heading for the oil pan. Nothing is in the cylinder except maybe the head of that valve but I don’t think it has broke off yet. I also believe if the follower failed first, the valve would never open and could not get smacked by the piston. We need to see the heads off.
     
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  4. Redfire_Jimi

    Redfire_Jimi Junior Member

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    This is what I am hoping for.

    Update: I spoke with a machine shop that specializes in cylinder heads. I will be removing the passenger side cylinder head this weekend and drop it off hopefully early next week for a full diagnosis.
     
  5. Redfire_Jimi

    Redfire_Jimi Junior Member

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    Quick Update: I am half way through pulling the heads. I did take off the intake manifold and observed a broken intake valve (see image below). Also, I know that I need to have the head completely off the engine to do a full damage assessment.

    Questions: Is this head salvageable?
    broken valve.jpg
     
  6. whitmanink

    whitmanink Member

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    if your luck is anything like mine,, the head is gonna be trashed ,, thats odd that yours looks like mine did ,,, (the valve broke off about half inch from valve head )

    anywho , lets us know what you find,, my block is trashed so thats that ,, as well as my passenger side head,, still have no idea why or how the valve did what it did
     
  7. Redfire_Jimi

    Redfire_Jimi Junior Member

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    I honestly don’t know what to think at this moment. I’ve been in a quasi-depression state for the last month.
     
    Last edited: Jul 12, 2022
  8. whitmanink

    whitmanink Member

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    i feel your pain all too well , fingers still crossed for ya tho
     
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  9. Redfire_Jimi

    Redfire_Jimi Junior Member

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    Okay gentlemen. Passenger cylinder head was removed (see pics below).

    Observations:
    1. Cylinder head damage seems to be isolated to one area.
    2. Piston head has deep scoring.

    Questions:
    1. Can I just replace the deeply scored piston head?
    upload_2022-7-24_16-14-5.jpeg
    upload_2022-7-24_16-13-35.jpeg
     
  10. Dino Dino Bambino

    Dino Dino Bambino I have a red car

    Age:
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    I'm glad the piston's still intact so there won't be any debris in the oil pan. The good news is that your engine is rebuildable. The bad news is that the MHS passenger side head is scrap. I suggest you look for a salvage engine so you can scavenge a piston/rod assembly plus the passenger side head to replace your damaged items.
    The question then is whether to have the salvage passenger side head ported to match your MHS driver's side head, or just replace the heads on both sides with the salvage unported units.
     
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  11. Redfire_Jimi

    Redfire_Jimi Junior Member

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    Hey Dino, I havent had a machinist inspect the head yet, but I was hoping the head could be repaired by a professional.
     
  12. whitmanink

    whitmanink Member

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    foreyes has a youtube channel , he is selling his used piston , connecting rod,combo for like 250 ,,

    he also has a passanger side head , but theres like 3 or 4 deep exhaust bolts broke off in head that need extracting
     
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  13. whitmanink

    whitmanink Member

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    i would also clean out that bore and make sure there isnt scoring at all on that cylinder wall, if so , you will need to get that taken care of before installing new pistions
     
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  14. Dino Dino Bambino

    Dino Dino Bambino I have a red car

    Age:
    59
    3,397
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    It's not impossible to repair but it would take quite a bit of time for a skilled machinist to weld in new aluminum to fill the defects, grind it back, insert a new intake valve seat, and replace a valve guide. You'd also need to find a single matching intake valve (I assume it's 1mm oversize).
    Consider yourself EXTREMELY fortunate that the broken valve head wedged itself firmly in the valve throat and didn't get bounced around inside the cylinder by the piston, and that the valve stem was still in the guide. Otherwise you'd be looking for an entire replacement engine.
     
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  15. Midlife Crises

    Midlife Crises Senior Member

    1,476
    978
    What does MHS have to say? Perhaps they have another head ready to go.
     
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  16. Redfire_Jimi

    Redfire_Jimi Junior Member

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    I spoke to a gentleman, he requested I email them all the pics and a detailed summary.
     
  17. Redfire_Jimi

    Redfire_Jimi Junior Member

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    I thoroughly inspected the cylinder wall and it surprisingly undamaged. I can replace the piston, but I am worried about the need to rebalance the rotating assembly afterwards. I am hoping that replacing the piston with the exact same copy shouldn't require the need to rebalance. *Fingers crossed*
     
  18. Redfire_Jimi

    Redfire_Jimi Junior Member

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    Hey Dino, I may have to explore this route solely because I want to keep this head. All the porting work that was done wasn't cheap.
     
  19. whitmanink

    whitmanink Member

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    the odds of you getting a piston the exact same weight as the the original one is slim at best,,
    altho the weight difference would be minimal and induce a slight bit of vibration if any,,

    now if your going high HP or blower,, than i would want to match them ,,, but count on having to match the con rod
     
    Redfire_Jimi likes this.
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