Grinding, " diesel " noise under valve covers

I'm not the final say, just a prediction.
Maybe you'll see piston to head contact. Idk the motor...but if it was scuffing you can see it from the bottom/ oil pan side.
With a stethoscope you will hear it prominently around the plug area on the cyl head. You won't hear much if at all at the pan rail .
Couldn't hear anything under the car. Jacked it up, fired it, and crawled under. It's quite down there