help needed... spark plug decided it wanted to have nothing to do with my head...

[TC535i]

So I'm driving along, and all of a sudden, the 540i/6 starts missing.
Pull over, pop the hood, and the driver side engine cover is bulging
and contracting in time with the miss. Pull the cover, and see the
carnage.

Coil pack has blow off half way down its neck, spark plug looks like
it managed to get completely out of the hole, and on top of all that,
it looks like it decided to take the nice soft hot threads of the
aluminum head along with it. Oh, did I mention it's a
single-electrode spark plug that according to the markings and jagged
metal, used to be a 4-prong plug?

So... that's the situation. I've got a couple options, I guess. Buy
a new coil pack, put it on top of a spark plug, bolt it down, and hope
the coil nuts hold the spark plug down hard enough to seal the
combustion chamber? Have them try and helicoil the head on the car?
Pull the head and work on it? Swear profusely?

I tried the last, and the car's still doing the same things. What do
you guys I think I should try next? I think I'm gonna do that last
one again, just to be sure of the results.

Well, I *WAS* having a good weekend... :(

[Paul in NZ]

dont know,but i am feeling your pain!

[stargazer_61]

When you say "try that last one again", do you mean swear profusely again? Man, I've tried that so many times, and it never seems to make the car better :)

That sucks! Seriously, you are going to have to have the head helicoiled or replaced. There's no way the coil pack will hold the plug in place. And with three prongs floating around in there? I'd be seriously worried about causing collateral damage. Are they still in the chamber?

John

[whiskychaser]

My coil packs have a small amount of spring in the base- no way thats going to hold a plug in. I think you already proved that :-) Dont know if they can helicoil the head while its on the car. I'd just be a little concerned about swarf that would drop down into the cylinder if they have to drill it out. Seems strange that the plug tip was damaged. Hope you can sort it quickly and cheaply

[Rus]

Considering the fact that the plug tip shows damage, it's likely that the metal from that has made its way into the combustion chamber. Simply helicoiling the plug hole won't let you inspect for any damage inside the cylinder. I'd be more inclined to pull the head, since if there is damage inside, heli-coiling will not fix it and you'll be pulling the head anyway afterwards. Just my $.02

[winfred]

helicoil it and go for it the remains of the plug are long gone, blown out the exhaust, the same thing that will happen to the cuttings, if you are worried you can roll the engine over till the exhaust valves are open and hit the plug hole with compressed air and blow the crap into the exhaust, the tap can be loaded with grease and retain most of the chips too. this problem starts off as a loose plug and gets worse, once it makes it's way out the spring pressure of the coil jackhammers the threads

[Ross]

Yow that sucks.
Chances are good whatever bits of electrode came off have been blown out into the exhaust already. Have a look in there with a scope to see if there's any more damamge.
A Heli-coil WILL repair the threads, wether it can be done with the head installed is another issue.
No way will the coil pack hold this together.

[BMWCCA1]

Electrode bits are magnetic (or rather ferrous and attracted to a magnet). Go fishing (at TDC would be best). Then, if you have one, run a spark-plug tap through the threads, vacuum, and try a new plug. You might get lucky. Of course the question is who installed the plug? If it was over-tightened, the threads may be trashed. If just loose, they may only look bad at the top from all that knocking around. Good Luck!

[Chris'91'525i]

I've had excellent results using, http://www.timesert.com/index.html for repairing some spark plug holes on air cooled VW heads.
Kits are pricey, but superior to Heli-coils for repairing spark pug and drain plugs, IMO.......
They have a neat tip for removing metal bits in the cylinder by rigging a small tube to a Shop-Vac hose.....