There are things I don't understand (I know, that doesn't mean much but I'd like to ask at least):
-The piston rings are probably not made from aluminum but steel/ cast- something that expands more the way the sleeve would than the piston would, they have a gap allowing them some expansion (about 0.003 to 0.006 inches in diameter)
-If a piston ring could crack mechanically away a part of the piston wouldn't the ring crack itself?
-Everything looks more melted and not ripped away to me, both the area below the piston rings and above them and also the small material deficit on the crown?
-There is no debris around,would've expected at least a little bit on the piston head?
-bishoptf writes "
had this happen a couple of times last summer but only at wot". That does sound more like slowly developing and like "warm seizure"?
Thanks in advance if someone would care to explain
But anyway: Would that change the way to rebuild this engine? Special precautions?
@bishoptf: Thanks for the latest pictures
How many hours ago did the engine start to stall if you remember?
Did you get the "not getting temperature" alarm when idling? (One beep in some minutes interval)
And yes, you're right: Servicing all injectors and rails seems expensive but I think it's essential now, especially as you're still thinking about a lean condition and after your check of the fule lines (even if the fuel filter should keep almost everything of that out of the system).
Concerning the direct air injectors there is a special procedure testing the valve movement (?), requiring a special tool and a dial indicator- don't know if it's a really good idea to do it yourself...