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Car tried to shoot itself...


Z34-5speed

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Ok, so today i go outside to crank my car to let it warm up and it tried to shoot itself.

 

I turn the key and as soon as it cranks...POW!!! and then starts running really rough. I immediately shut the car off and pop the hood. When i open the hood i find my center spark plug laying on top of the injector cover, still attached to its plug wire. There is parts of the plug wire everywhere, the little fibers were strewn everywhere. I then look up and notice that there is a huge gash in my hood liner, then i realize what the bang was. So i close the hood and see where the spark plug attempted to exit my hood. It cracked the paint and all kinds of fun stuff, will have pics tomarrow.

 

I then pulled out another plug and tried to thread it into the center hole, it just spins and spins, doesn't catch anything. So, what do you guys think happened?

 

I haven't taken out those plugs for at least 5 months. Whats the likelyhood the plug just backed out and then blew out, or did i just get stupid high compression for no apparent reason?

 

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I have heard of this on Ford motors. The replacement plugs do not have enough threads to hold it into the head. You are going to have to rethread your spark plug hole in your head.

 

When was the last time you changed your plugs? I always like to make sure the threads are the same length. I don't remember which brand they were having problems with.

 

 

Bummer. Hope everything works out.

 

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Yup, that happened to my old 2.8L in my first Grand Prix. Funny thing was, I bought a set of helicoils, did a shitty job of helicoiling it, leaving a very small gap in the cylinder head for air to escape between the plug hole threads. I drove the car like this for months without any major problem.

 

Either you're retapping/helicoiling the head, and risking metal shards in your motor, or you're replacing the head.

 

Helicoils are basically just surrogate threads that you put around a spark plug. They come with a tap that you use to retap the head to a larger size so the new threads will fit into the head, allowing you to use normal size spark plugs.

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I feel your pain - boosting my car last Monday the hood fell down from the wind on top of the booster cable clamps and dented anc racked the paint on my hood. Sorry to hear about that.

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I've never personally seen it either - but it does happen. I guy on here from Ontario used to drive an older GP, like 1988 model had that happen to him. I don'tt hink he frequents the board anymore though.

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I had that happen to my dad's 1987 Buick Century with the 2.5. Hammerin' down the backroads near 100mph, and all of a sudden, a big BANG, and a bunch of glowing sparkly stuff came out from under the car, and it was hitting on three cylinders. Turned out a spark plug had blowed up or something, and it was crazy. Replaced the plug, and we were good.

 

Good luck with your car.

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crazy stuff right here.

 

you can try using a heli-coil without drilling, but the best way to do it would be to remove the head and have one installed properly, or just replacing the head.

 

 

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I don't recall ever seeing that happen to a 3.4 DOHC, but I've seen a few Ford modular V8's that had this problem. :redface:

 

EDIT: Are you going to repair it yourself or have a shop fix it?

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I don't recall ever seeing that happen to a 3.4 DOHC, but I've seen a few Ford modular V8's that had this problem. :redface:

 

EDIT: Are you going to repair it yourself or have a shop fix it?

 

Currently it sits at the local Chevy dealer. :sad:

 

 

I tried to take it to a few places but they wouldn't touch the motor. Tomorrow they are going to try and re-tap it, and see how that goes, if it doesn't work then hello to a new head, or two.

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I saw the techs at the dealership I worked at work on many northstar v8's and they were always retapping the block and heads because the aluminum was so soft. The heli-coils they used were a Kent Moore part, and they spun them in on the existing threads sometimes. If they are going to drill out you spark plug hole they better be careful not to shred your cylinders.

 

 

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Lol, i wish.

 

They re-drilled the hole today. I am going to pick it up tomarrow. They are only going to charge me $250, thats for the new plug wires, new plugs, drilling/tapping the hole, and the labor, and this is a Chevy dealer!!! :willynilly:

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Not true to comment above we have SP hole rethreaders that you place into the head and then tighten the upper adjust nut to open the thread up, so you start at the bottom where good threads are and re-tap going up so all the filings can be brought up in the plug wire hole and removed.

 

SPKTHR03_Large_1.jpg

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