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    Thread: what causes a headgasket to blow between cylinders?

    1. Member
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      07-14-2007 12:43 AM #1
      so mine burned through between cylinder 3 and 4 driving back from K-Mart with milk @ 35mph in 4th gear.
      the head was decked for sealing and the gasket was only a few months old. it was the fiber style with the metal sealing rings around the cylinder.
      what gives?





      Modified by weeblebiker at 6:07 AM 7-14-2007
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

    2. 07-14-2007 10:34 AM #2
      Looks like your head maybe cracked between the cylinders, thats the only thing i can think of that would have coused that.

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      07-14-2007 12:15 PM #3
      nope. I'm thinking it was just too cheap a gasket. I got an aba gasket going in, at least next time I won't have to scrape fiber material off the aluminium head. I'm just waiting for my buddy to come over so he, I and my 14 year old garage knomb can set the head back on and keep the exhaust manifold out of the way.
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

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      07-14-2007 02:54 PM #4
      car ever been over heated? the head could have warped in that spot. go deck it.
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    5. Banned skillton's Avatar
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      07-14-2007 03:46 PM #5
      It happened to me twice on my old 16v(with 2 different heads), I think it's mostly caused by detonation. Take the head to a machine shop and have them check for cracks, my first one was cracked, I didn't bother checking the 2nd one, I just put in a rebuilt one, also the timing belt had skipped a few teeth on both occasions.
      Have it checked for cracks and make sure the valves are still straight(if you didn't check the timing before removing the head). If it's all good, put it back on with new head bolts and a metal headgasket

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      07-15-2007 09:52 PM #6
      well, I'm gunna chalk it up to a cheap hg. the head was decked last fall, it has never come close to overheating, I have water and oil temps. when I cleaned of the exhaust crud today, there was no evidence of a crack, thered be a black hairline left by the gasses passing through the crack from one cylinder to the other in the deck polish. also when I did the hg last time I placed the head on myself, I probably buggard it then.
      I'll know in a few months



      Modified by weeblebiker at 2:57 AM 7-16-2007
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

    7. Member Rev Jerry's Avatar
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      07-15-2007 10:06 PM #7
      Quote, originally posted by skillton »
      ..... it's mostly caused by detonation.....

      Bingo. Low rpm and detonation will do that everytime.

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      07-16-2007 07:15 AM #8
      hmm
      I did megasquirt v2.2 with msns-e controlling spark this spring
      and I did have the idle and low map part of the ve table on the lean side for a few months, (it drove good though)


      Modified by weeblebiker at 12:28 PM 7-16-2007
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

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      07-16-2007 09:26 AM #9
      so could low rpme detonation just blow the gasket and not crack the head?
      or is the blown gasket a result of the cracked head
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

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      07-18-2007 12:33 AM #10
      it takes way more to crack a head than to blow a headgasket....trust me I know....

    11. Banned skillton's Avatar
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      07-18-2007 06:13 AM #11
      Quote, originally posted by weeblebiker »
      so could low rpme detonation just blow the gasket and not crack the head?
      or is the blown gasket a result of the cracked head

      when it happened to me, the head was cracked as well. it wasn't really noticeable, but I had it checked by a machine shop and they told me it was cracked.
      Mine blew at around 3000rpm and ~1/2 throttle the first time, then it happened at around 2000-2500 at 1/3-1/2 throttle

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      07-18-2007 06:54 AM #12
      are you boosted or na?
      from what I've read, its alot easier to blow the gasket by detonation boosted than na and the damage is more likely catastrophic
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

    13. Geriatric Member need_a_VR6's Avatar
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      07-18-2007 10:18 AM #13
      Detonation is detonation and even NA you can blow the gasket quickly that way.
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    14. 07-18-2007 11:08 AM #14
      probly some stupid questions.....
      was the head warped prior to decking last time?
      if so, did the machine shop properly clamp it down before machining?
      when you did the last headgasket - did you use new head bolts?
      I would suggest ARP studs (cheap @ Summitt Racing) and torque them to 75ft/lbs instead of the 65 on their sheet.
      BTW - from the looks of your combustion chambers and valves i'd say you were running way to rich, or burning oil.


      Modified by OhioBenz at 11:10 AM 7-18-2007

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      07-18-2007 06:32 PM #15
      the head was straight prior to decking. I don't use warped heads even decked cause the cam alignment is off.
      the head was pulled and replaced for bent valves.
      new gasket and bolts, I think I may have torqued em to 60ftlbs plus 180* instead of 42ftlbs. I put the exhaust manifold on the head before trying to set it on the block.
      well the oil was fresh, dribbled out onto the head when I pulled it off, hense the wet look. they're not that coated


      Modified by weeblebiker at 11:33 PM 7-18-2007
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

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      07-19-2007 12:39 AM #16
      this motor was run with megasquirt??

    17. Member
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      07-19-2007 07:17 AM #17
      yuppers
      ms was installed after the last time the head was off
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

    18. 07-19-2007 07:43 AM #18
      Quote, originally posted by weeblebiker »
      there was no evidence of a crack, thered be a black hairline left by the gasses passing through the crack from one cylinder to the other in the deck polish.

      You cant always see a crack with just your eyes. Either get some 2 part crack tester (penetrant dye and developer) or have a machine shop do it for you. It'd be better for a machine shop to check it, though, because they're experienced and know what to look for. For the $30 it costs its worth it, I have a head inspected any time I take it off, and have been surprised by how many have been cracked/warped.


      Modified by Jetta2dr at 7:44 AM 7-19-2007

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      07-19-2007 03:50 PM #19
      I think in this case a crack would be visible, the head was decked prior to the last install, and I can still make out all the decking swirls across the area once I rubbed off the soot.
      my main question is"is the head always cracked in this situatiion?"
      It's all a little mute at this point cause the head has been reinstalled since sunday morning. I just need to know if another head gasket and bolts should be my next purchase soon to toss on another head.
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

    20. 07-19-2007 10:58 PM #20
      i've had 3 ABA headgaskets blow on different 16v motors with ARP studs torqued to their specs - 65 ft/lbs (for aluminum heads).
      I now torque them to 80 ft/lbs with fible gaskets (stock) and 70 ft/lbs with ABA steel ones.
      My son just did a 7200+ mile raod trip with his GLI, and I ran my 90 GLI for about 10,000 before pulling the motor for other reasons, the 89 is getting driven daily - run hard and no more issues.
      I caught this one pretty early... No.1-2 cyl



      Modified by OhioBenz at 11:06 PM 7-19-2007

    21. 07-20-2007 12:01 AM #21
      Quote, originally posted by OhioBenz »
      i've had 3 ABA headgaskets blow on different 16v motors with ARP studs torqued to their specs - 65 ft/lbs (for aluminum heads).

      Did you retorque them after some break in? I've heard that you're supposed to. In my VWMS group A workshop manual they specify a procedure with a couple retorque-ing periods on whatever kind of bolts/studs they used in their rally engines.

    22. Member
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      07-20-2007 09:28 AM #22
      and how many times was there head damage?
      '87 rocco ,ABA16VitbT, dual exhaust cams, megasquirt 2-extra v2.2 box
      volvo TD04h-14T turbo, celica intercooler, corolla manifold, gsxr itbs,beer can, staged injection, maf, COPs
      I really don't trust myself and have a tendency to catastrophize, but I don't even trust that I screw things up, so I'm pretty damn good at making and fixing stuff!

    23. 07-20-2007 10:03 AM #23
      Quote, originally posted by Jetta2dr »
      Did you retorque them after some break in? I've heard that you're supposed to. In my VWMS group A workshop manual they specify a procedure with a couple retorque-ing periods on whatever kind of bolts/studs they used in their rally engines.

      I've heard the same but cant find anything in writing that supports that. ARP certainly doesnt in their paperwork that comes with the headstuds....
      VW stock headbolts are a stretch type and should not need re-torqueing.
      The head in the pic was just pilled off and put aside - never checked because I had a fully prepped P&P'd head sitting around. I usually catch them pretty early - so no, no damage at this point.

    24. 07-23-2007 09:30 PM #24
      I have always ran the ARP undercut studs on my 8vt which does not need retorqued. Never had a problem with it blowing hg, I torqued it to 75 ft/lbs. From what I heard the regular ARP head studs need to be retorqued while the undercut doesnt require retorquing.

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      07-24-2007 04:58 PM #25
      Quote, originally posted by need_a_VR6 »
      Detonation is detonation and even NA you can blow the gasket quickly that way.

      Then he has to look for the source of the problem elsewhere,specifically how fuel is being distributed between cylinder 3 & 4.

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