rod bearing in the pic has no scoring so it is not an oil related failure.

when they check the air filter something could have been ingested into the air intake or just vandalism. hard to prove sometimes.
you want to find something related to the air filter or its hardware to prove negligence on their part.
if you find something other than air filter hardware then it could be vandalism.

one time I was called to do forensics on an MB straight 6 gas engine.
It had a foreign object ingested into one cylinder only, broke the piston, damaged combustion chamber however no valve seat broke off in that cylinder.
shop claimed the piece related to the intake flap had its nut come loose and into the air inlet stream.
the nut was all banged up as if it was smashed by the piston.
I told them something was ingested but it was not that nut because it was to big to get past the valve openings.
I was embarrassed for them because of their red faces.




you can look through the debris for something unusual and not part of the internal engine to prove vandalism.

__________________

79 240D my current toy
42 years a Diesel addict

240D sold
250SE sold
220D sold
280C sold
280S sold
300D (2) sold
300CD sold
300DT sold
300SD sold
380SL sold