Engine died after 20 minutes

[zipzip]

Sorry to hear about your problems!

I think that the pump drive shaft can come out of the pump and drop into the pan if the retaining washer is not in place. In my engine, it is like one of those push caps on a kids toy (you know the ones that you hammer and hammer on until they are bent and mangled but holding - then you realize you forgot a small part and have to somehow pry them off!). Anyway... if that washer drops too far down the shaft, the shaft will be able to pull up and out of the oil pump, then kerplunk, into the pan.

I think the broken part of the lifters look like a brittle fracture, which either means a cast part, or some sort of heat treatment. Even hard parts will wear with no oil. The lifters do not show a lot of heat though, so I think oil was present, but maybe not in the quantity needed. You noted some "supplier problems" - could the lifters have been out of tolerance on the OD, allowing them to "cock" in the lifter bore and bind up? This might explain the lack of damage to the pushrods. Or could they have been allowed to come out of the lifter bores in the block enough to bind, similar to pistons coming out of the cylinder if you get too much stroke on the crank?

Good luck and best wishes!