Missing idler pulley???

[BCS_ZHP]

$h1tballs. My indy said today it sounded like something he wasn't equipped to handle, so I went out there and opened it up. Valvetrain looked clean, and plugs 1-5 looked normal. But #6... !! Crap!




VANOS looked a little burnt--is this normal, or could that be a clue as to what happened? My theory is that there was valve contact in #6, the valve broke off and bounced around, thrashing this plug and probably everything else in the combustion chamber. I'm open to suggestions.

Should I start a new thread for this?

Here's a thought/idea -- ask your Indy to pull/check the DISA, probably only an hour of labor. If the DISA flapper lets go/breaks it can potentially get ingested in the intake system, maybe a piece of that butterfly flap broke and went thru the intake valve on cyl #6, a couple strokes of the piston and it hit the spark plug mangling it like your photo. It's just an idea/hypothesis, I've never heard of one single valve breaking off into a cylinder on a BMW but guess that's possible too.

[JAZZHP]

The bigger question at this point, regardless of what caused this mess, is whether the likely expense of removing and probably rebuilding the head, and maybe serious work to correct other damage inside the cylinder, is worth the effort versus replacing the engine. It only has 100k on it, I didn't expect to see anything this serious go wrong if everything was otherwise working well and treated well.

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[wsmeyer]

If a valve breaks the engine usually seizes as there just isn't enough room in the combustion chamber at TDC for any piece of a valve. That being residue from a burned piece of plastic from a broken DISA sounds plausible, especially how common it is for those to break.

Is the car manual? If so the noise you heard might have been the dual mass flywheel thrashing around as the engine stumbled on 5 cylinders. If you've never heard it thrash before it is rather unnerving.

[slater]

just seeing these plug carnage pics now... yikes. is it melted? hard to tell from the pics. what does the top of the piston look like if you shine a flashlight down in there?

[JAZZHP]

What little I could see through the plug hole looked like a dark, dirty mess. I couldn't make out any specific shrapnel, bit if it was a piece of plastic DISA valve then maybe all is not lost. I'm out of town now, but I'll pull the DISA in a few days to see if that's likely. I may see if I can get a scope to get a better view before making a decision.

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[Sockethead]

Harbor Freight has relatively inexpensive scopes... even cheaper with the 25% discount from the monthly flyer...

[Dave1027]

Car seems to run perfectly fine--smooth at all rpms, no cooling or electrical troubles, serpentine belt is under tension, no squealing, but wtf??? Am I missing something?

I must be missing something too. How was your car running "perfectly fine--smooth at all rpms" with a spark plug in that condition?

[JAZZHP]

I must be missing something too. How was your car running "perfectly fine--smooth at all rpms" with a spark plug in that condition?

#6 ran perfectly smooth for the entire year that I owned it, until all hell broke loose and it ran for about 10 more seconds sounding like it was flying apart until I could pull over. That's when the spark plug got damaged. Something broke loose inside the #6 combustion chamber. The most popular opinion seems to be the DISA valve came apart and got into the chamber, then the plug got beat to death by the shrapnel.

[JAZZHP]

Harbor Freight has relatively inexpensive scopes... even cheaper with the 25% discount from the monthly flyer...

Been shopping at Harbor Freight a lot lately--I'll definitely check this out.

[JAZZHP]

Well, I'm struggling not to throw up after seeing what happened to my #6 cylinder. DISA was fine, completely intact and functioning normal. I bought a scope at Harbor Freight, on sale--great deal. What I saw with the scope I don't even want to say. I'll give you some hints, and if anyone guesses I'll post the pictures, but it's too painful right now. The hints are that it was 100% avoidable, 100% my fault, and as an airline pilot who understands basic aircraft maintenance procedural requirements I should definitely have known better. Suffice it to say the head and top of piston are trashed, so I'm thinking an engine swap would be a better option than a rebuild. And since my cams appear quite clean (see earlier pictures), swapping them into a low mileage 330 non-ZHP motor is probably the most economical way to go. I'll expect a few recommendations for an M3 motor, or an LS1, but I don't see that being economical or practical, given the reason I bought the ZHP in the first place was to avoid the M3 mechanical concerns, but I will consider this. Either way, I still want to throw up, as I just discovered the carnage an hour ago. CRAP!!