Piston hitting spark plug!:(

NokaoiMK3

Drifter..
Jul 27, 2008
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I figure.. Even if they were i probably wouldn't.. So i will post some pics after the head gets fixed at machine shop and as i put the engine back together..
 

te72

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IJ.;1777051 said:
Still don't think it's possible Brad, look at the pic then consider the piston is dished in the middle where the plug is.

head6a.jpg
I don't know how else to explain what went wrong in my case though Ian, spark plugs don't just smash themselves do they? Foreign object always seemed the most likely candidate to me, but I never tore the engine down to inspect, figured it was a fluke. Looking at your picture (how did you DO that anyway, lightsaber?), I would think any foreign object would have to be fairly sizable and extremely lucky to hit just between the plug and piston without getting hit by a valve first...

Like I said, I dunno, all I have is the experience myself, but no answers as to why.
 

NokaoiMK3

Drifter..
Jul 27, 2008
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Yeah havnt removed the valves yet to take a look at the seats but im sure there is some sort of damage to the intake valve seats if not both the intake and exhaust valve seats.. we will see.. But yeah im impressed with how little of damage was actually done given there was foreign metal in my combustion chamber.. But also as soon as i heard anything i shut it down and towed it to my shop and tore it down
 

te72

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IJ.;1777371 said:
Detonation can be very destructive Brad, just don't think there is any chance of the piston physically hitting the plug per the above pic.

Ahh, perhaps we're not on the same page here, at least with my case. I was assuming debris inside the combustion chamber is what killed my plug. Totally agree with you, kinda hard to argue with that picture, no way a piston and plug are kissing in our engines. :)
 

IJ.

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Mar 30, 2005
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te72;1777674 said:
Ahh, perhaps we're not on the same page here, at least with my case. I was assuming debris inside the combustion chamber is what killed my plug. Totally agree with you, kinda hard to argue with that picture, no way a piston and plug are kissing in our engines. :)

I'm guessing the "debris" was the ground strap bouncing around before escaping, something would have to have been HUGE to sit on the piston and hit the plug and snap off the ground, most times it will embed in the piston or at least leve a good imprint.
 

te72

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IJ.;1777688 said:
I'm guessing the "debris" was the ground strap bouncing around before escaping, something would have to have been HUGE to sit on the piston and hit the plug and snap off the ground, most times it will embed in the piston or at least leve a good imprint.
The ground strap was still attached to the plug though, that's what confused me. :)
 

te72

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Rattle? Not really wanting to be spoon-fed here, but I think you've lost me sir. Detonation?
 

IJ.

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te72;1779088 said:
Rattle? Not really wanting to be spoon-fed here, but I think you've lost me sir. Detonation?
Google "Incipient detonation" a "Rattle" is the next step that you can actually hear, by the time you've heard it it's been doing damage for a long ass time... :(
 

te72

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Well, one thing is for sure, I'm definitely not an engineer after all that reading. What I think I got is that incipient detonation is the 'pinging' sound spoken of, and that by the time you realize its happening, it's most likely already fried something in the engine unless you shut it down by some means of detection, whether through EGT changes or using some sort of stethoscope... Maybe I'm misunderstanding what I found on the subject, but that's what I gathered. :dunno:

Still makes me wonder what happened though. I drove that car for at least a year or so after that without consequence... or at least nothing catastrophic consequence.
 

IJ.

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Can't actually hear incipient but it's doing damage, by the time it rattles hard enough to hear it's doing big damage, this is why I sit here and chuckle at people "tuning" their engines by "ear/feel"...

You might have just got a load of bad fuel it happens form time to time, rattled + leaned out and closed the plug up, next tank of fuel "fixed" it ;)
 

te72

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IJ.;1779429 said:
You might have just got a load of bad fuel it happens form time to time, rattled + leaned out and closed the plug up, next tank of fuel "fixed" it ;)

Good to know man. The idea of leaning out mine kinda makes me wonder, given that it was NA, but I suppose shit happens. Changed a spark plug and never had the issue again. Hell, drove for some ~40-50 miles with a bum 5th cylinder. God that thing was rough on the way back haha...
 

92TealSupra

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Sep 2, 2008
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IJ.;1777036 said:
Pretty sure with the head design it's impossible for the piston to hit the plug as it'd bottom out on the quench pads first..

I was going to say this as well. Ill get some pic's first. Also iv had some 7M's that when the rod bearing went it hit the head, but never the spark plug.