What is this thing-in the combustion chamber?

[mo-mon]

1988 Carrera. Changed my spark plugs last Saturday. Cruised through 1 to 5. Struggled like hell pulling out no. 6. When I finally got it out, I noticed nicks in the thread of the spark plug.

Prepared another plug to use as a thread chaser. Greased the chaser & slowly put it in. About half way in, there was resistance. I backed it out & this is what came out, stuck on the grease-




WTF! It is plastic-couldn't cut it with a cutter.

Where could this have come from?

Intake? I pulled out the air cleaner box & the AFM. Nothing broken inside.

Chain ramps? Is it possible? Please help. Sorry for the enormous photo.

[JohnJL]

Debris from around the intake/in the fins that fell in when you took the plug out?

No way for the chain ramps to get there.

[stownsen914]

Could it be carbon? Might want to get a borescope in the sparkplug hole to see if something is going on ...

[mo-mon]

I will check the periphery of the engine for broken plastic.

Will also try to get a borescope or buy a micro camera to see what's going on inside.

Thanks for the input.

[jlex]

Almost looks like insulation from a crumbling speed/reference sensor wire. Had similar looking pieces all over as my wires were deteriorating.

[tirwin]

Someone told me that some auto parts stores have tools for rent. You might be able to rent a scope.

[porsche930dude]

they make ones that plug into a smartphone theyre like 10 bucks and theyve got a smaller head and i hear theyre good. all over ebay

[Trackrash]

Originally Posted by porsche930dude

they make ones that plug into a smartphone theyre like 10 bucks and theyve got a smaller head and i hear theyre good. all over ebay

I just bought one off Amazon for $16. Works with a PC as will as an android. Well worth the $ if you ask me. Arrived in two days to boot.

[mo-mon]

Looked around that side of the engine & didn't see any broken plastic. I will take off the upper valve cover on the passenger side & check further.

[famoroso]

Originally Posted by Trackrash

I just bought one off Amazon for $16. Works with a PC as will as an android. Well worth the $ if you ask me. Arrived in two days to boot.

Link?

[CCM911]

Could it have broken off from your plug cap? Is the cap on that wire newer than the others?

[Trackrash]

Originally Posted by famoroso

Link?

https://www.amazon.com/Best-Sellers-Industrial-Scientific-Borescopes/zgbs/industrial/401578011

7M 6 LED USB Waterproof Endoscope Borescope Snake Inspection Video Camera 7mm - Newegg.com

[prschmn]

I've seen a LOT of broken fan belt bits that look remarkably similar and they do tend to work there way back towards six quite often.

[Bob Kontak]

Originally Posted by CCM911

Could it have broken off from your plug cap? Is the cap on that wire newer than the others?

+1 My first thought.

[Nine9six]

Using a new plug as a thread chaser is not recommended.

Good thread posting though; I just picked up a bore scope that plugs into my tablet micro port.

Sorry, any guessing as to the foreign material you pulled out, would be just that; guessing.

p.s. My hands never look as clean as yours, even after washing! How do you do it?
; )

[Walt Fricke]

"Using a new plug as a thread chaser is not recommended."
Well, he said he "prepared another plug" to use as a thread chaser. I use an old plug (I have lots of these, way more than sensible)into which I have cut slots axially across the threads for some cutting action.

As to the debris, I am clueless.

But does it look like it has been tumbled around and beaten up in the combustion chamber? I, too, think it is more likely that it is debris which fell in when the plug was removed no matter what it is - something which got into the intake tract and the combustion chamber is unlikely to find its way part way up the spark plug hole, given that with the plug in there is no way for it to get up there. And it is pretty unlikely that it was stuck to the electrode of the plug which was removed, but fell off half way up.

Bore scopes are your friend, though.