Crankshaft Bearing Caps: Damaged Threads - Mystery

hello

I have an old TDI engine block, a disassembled AEL 5-cylinder. The block itself, as well as the crankshaft and one connecting rod, are defective. I just felt like taking it apart, and besides that, some parts were needed elsewhere.
Anyway, I won't be using the block or the broken parts anymore, regardless.

Yesterday, something quite strange happened. I personally removed the brackets, or housings – or whatever they're called – that hold the crankshaft. All the screws came out normally, and I still have the screws here – they are definitely all in perfect condition and all the same length.
That's exactly why I'm now surprised that I suddenly have three defective threads on block three. The threads are stripped – so something seems to have broken off.

http://localhost.co.at/car/gewinde.jpg

It sounds really silly, but I'm extremely interested in how this could be possible - especially since I have the screws, which are okay, and I definitely didn't strip any screws during the disassembly. (screws are also visible here --> http://gallery.localhost.co.at/d/10411-2/DSC_4573.JPG))

Is there a logical explanation for this?

THANK YOU

Sure, here is the translation of the text from German to English:

"Hello"

You've disassembled a motor that was previously running (in some way), I see the 5 bearing supports are detached, and you have a 5-cylinder engine? Shouldn't it have 6 bearing supports and the corresponding shells?
Then that would be 2 x 6 = 12 screws. I see 10?
Are all the screws the same length?
That would be a case for the quiz page - picture search .

hi

Okay, we're getting closer to the solution. There really should be 6 brackets. So, one bracket is missing, as well as one screw.

That must be the explanation; exactly three screws and one bracket are missing.

I can't believe that something like this wasn't noticed during the disassembly. However, I also didn't work very carefully myself. As I said, the engine has a connecting rod failure, and the parts, including the crankshaft, are defective. In a way, the engine block is just scrap to me.

Although the engine was technically still running, it was partially disassembled from below by a (seemingly very skilled) mechanic in order to determine the cause of the engine damage for the customer.

If this is really the case, I have no explanation for how a mechanic manages to strip three screws, while I, as someone new to this, can easily remove the other nine without any problems.

Sure, here is the translation of the text from German to English:

"Hello"

I think it was different:

The engine had a connecting rod failure in one cylinder.
Either the cylinder is seized or the piston is jammed due to a blockage (possibly from the valves?).
The high force overloaded the two main bearings involved.
The screws were either elongated or broken off/damaged.

Okay, so the engine is supposed to have a connecting rod failure in the second cylinder, and the sheared screws are located in the center.