Mysterious Engine Failure Diagnosis/Disassembly + Bonus!

[SeikenFreak]

Eh thought I'd post this as it's interesting to me. And certain accents make everything better.

Summary: Mechanic/teacher tries to kill engine by dropping metal bits down the intake (Part 1) and then disassembles it to see the destruction and find the point of failure. (Part 2)



Spoiler
There doesn't seem to be an obvious reason for the engine dying. What do you think? Any ideas? Spark plug gap closure is mentioned in the comments, which does makes sense for ball bearings, but not so much for filings which is when it did finally stop. Hmm.

..And because I know my audience:

 

[08mojo]

I didn't watch the videos, but anything that could bridge the gap between the strap and electrode would prevent the spark plug from firing. Also, it doesn't take much damage to valve seat to prevent it from sealing the combustion chamber effectively, same for the rings.