TOPIC:

Just came back to write after I saw the photos yesterday, but scotch already said it for me so I want elaborate but rather confirm that's what you should do and consider.
What metal are the pieces (steel, aluminum, something else?), shape, look at them close, and the loosen bolts under the covers is what came first to my mind as well.

Maybe I missed this piece of information, but what area of the engine was the noise coming from?

Second look and an observation: I see black pieces of what looks like a chain or a tensioner guide.

I now have disassemble the head cover and everything look good up there. I did a visual diagnosis and nothing suspicious.disassemble the two tensioner timming chain and again all good there.Then disassemble the oil pane and at the same time the exhaust for Shure, no molten or propelled metal. in the oil a lot of metal peel and of course the scrin is filled with metal! There is two types of metal in there some magnetic so it metallic and other not like aluminum casing but don't see were and find like a half plastics bushing 1" in and 1"1/4 id but don't what is it.. I am going to dismount clutch and other cover like say Scotch, to see something of suspects and carry out an exam with endoscopic camera wherever I can see. I'll get back to you with the news.

A bearing plastic piece not a bushing? Perhaps a bearing went bad and is grinding now. Cant think of which from the top of my head. None really fits this size. Are there letters on it that Ii see or just indents? The magnetic properties of metal chips point to rotors. Definitely covers off and see further. Or is it a seal part of a disintegrated seal? There are some of similar size.

Perhaps this part of the thread should have it's own Topic ?

This seems odd. Maybe just a camera lens anomaly but: Is this a crack?



Same premise - Has this been previously repaired (welded) ? Seems too "lumpy" for a casting radius.



.....and just some random ideas:

I see this half moon is metal, right? It looked like dark rubber on my phone. In this case, that bearing at the end of the shaft with spacer is a good guess.