Help needed... Appantly the spark plug threw a fit and decided to take off...

[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 thing. 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... :(

[Jon K]

Tim that sucks and I have heard of this happening - how it happens, no freaking clue, but I have heard of it. i'd be more concerned about the piston tops than the head. I'd consider finding a borescope and checking out inside. That sounds like bad news.

[Tiger]

Yeah... you really need that tight seat at the spark plug... no other way around it.

[TC535i]

Car's at the shop getting helicoiled or whatever the guy uses.

Any idea what this is gonna cost me? They must be able to do it over the fender I'd think, and it seemed like they had a pretty straight shot, no real accessories in the way (2nd cyl from the grill, driver side)...

[Evan]

it's pretty simple and shouldn't cost much... but why did you put it in there without having a firm price?!

[TC535i]

it's pretty simple and shouldn't cost much... but why did you put it in there without having a firm price?!
Cuz I trust the shop wouldn't screw me (been doing my gf's and her dad's German cars for 20+ years), and I didn't really have any other alternatives.

What's "not much", a few hundred bucks for a couple hours to drill/install/clean, misc parts costs, etc?

[bsell]

Cuz I trust the shop wouldn't screw me (been doing my gf's and her dad's German cars for 20+ years), and I didn't really have any other alternatives.

What's "not much", a few hundred bucks for a couple hours to drill/install/clean, misc parts costs, etc?

"drill/install/clean"...hmmm. How will they get the shavings out of the combustion chamber so they don't score the hell out of the cylinder walls?

Of course the best way is to pull the head, find the pieces of parts, survey the damage to the block/piston to ensure only the head needs help, then spend the time on fixing/checking all of the spark plug threads. If one is bad, there may be other sickies hiding and now is the time to find/fix them.

My Dad's Grand National blew the porcelain portion of a plug out of the steel collar when his waste gate hose fell off one day. That engine drove for another 50,000 miles or so before sending a rod through the side...

So what have you been doing?;)

Brian

[TC535i]

"drill/install/clean"...hmmm. How will they get the shavings out of the combustion chamber so they don't score the hell out of the cylinder walls?
From what I hear, when they drill, they pack it with grease, which keeps most of the shavings out of the head. Otherwise, compressed air for anything that didn't stick, etc.

What was I doing? Nothing huge at the time, I've been driving it like it was meant to be. :) Always let the water and oil warm up before giving it too much... Nothing that could possibly cause a spark plug to come out. IMO, prev owner probably didn't crank it down enough, and after it backed itself out, it just kept bouncing around between the seat and the boot until it eventually destroyed the threads on a hot aluminum head (not all that difficult, really).

At least with a wire/plug design the stupid thing would have blown out instead of bouncing around stuck under a bolted down coil pack...

As far as checking the rest of the holes, I'm going to be pulling the plugs and replacing them all as a result of this incident, so I'll check them then... that kind of work I can do out in my driveway. Not so comfortable with trying to aquire a helicoil kit and use it on a BMW head, so I'll pay someone that knows what they're doing for that part.

[TC535i]

Got a call back... was an over the fender job, threw a large timesert in there... was pretty bad, he had to get a larger size one, I guess. Anyhow, put some oil in there, and fired it up... running great.

He also checked/tightened all the plugs for me, but I'm gonna pull em all and replace with the standard copper NGK's, I think.

[skr]

damn, i allways considered blowing out a plug more like an urban mith. i'm glad it turned out ok.

[TC535i]

damn, i allways considered blowing out a plug more like an urban mith. i'm glad it turned out ok.
Who knows if it just wasn't tightened, or if the threads were mangled from crossthreading or overtightening... no way to tell, really. Gotta be careful with these aluminum heads, it's not a very hard metal, especially up at operating temp. They recommend you don't even install/torque spark plugs until it's cooled down a bit...

[whiskychaser]

You know there are some lucky bastards around. If that was me I would be picking up bits of plugs, valves, head etc off the ground. You would need CSI to sort them out:-)

[E34-520iSE]

damn, i allways considered blowing out a plug more like an urban mith. i'm glad it turned out ok.
It happened on an old motorbike I had years ago - I kicked over the engine as usual. It ran for a few minutes then I revved it and ptchoo the spark plug shot across the garden like a mini fireball.
The best (or worst) one to see is an engine that has 'put a leg out of bed', or threw a con-rod. The damage that does to a block is something else!

Cheers,

Shaun M

[TC535i]

It happened on an old motorbike I had years ago - I kicked over the engine as usual. It ran for a few minutes then I revved it and ptchoo the spark plug shot across the garden like a mini fireball.
The best (or worst) one to see is an engine that has 'put a leg out of bed', or threw a con-rod. The damage that does to a block is something else!

Cheers,

Shaun M
Yup, happened to my buddy's E30 M3 the second he lifted coming thru 8 at Willow Springs (big track). Bang, loss of power, and a lovely view of the bottom end, courtesy of a new viewing window in the side of the block.

:(