How about the top come off a piston? I wouldn't have still been driving it to be truthful, whatever it is making the noise, it's metallic and broken, so all those metal fragments are buggering up what's left of the decent engine parts.
I had no where to stop I had a queue of about 200 Yds behind me on a country road and that ain't good last thing I want to do is cause an accident, I was also thinking it may have broken near the piston too I'm stripping it tomoz anyway so I'll know more then
If the crank is salvageable then I'm happy I can get the block re-lined so no biggy as long as it's got no holes in which it hasn't its ok
A good bottom end is prob bout a grand as un ground cranks seem to be changing hands for a fair bit nowadays , pull it apart and see what you find but my bet is spun bearing lunched journal, poss bent crank and rod :-( = ££££££ or big power rebuild time