my DIY engine rebuild

[hemonu]

I had that twice in my life, but on a motorcycle engine quite a while ago. A few thouhgts.

Root cause is usually a lack of oilf pressure / flow in the bearing. If the engine is very old and worn the gap may be too high to maintain enough pressure. If the engine is not worn, there may be a problem with the oil pump or an oil line is clocked. Both happened to me. I think it should be possible to grind and polish the crank to the next smaller bearing diameter as it looks. But you have to measure first.
If the bearing has really turned inside the piston rod, you have to change the rod. But I'm surprised that the clips at the corner of the bearings are not broken. When it happened to me the engine got totally overheated in a minute and the bearing was complety destroyed.