Lack of oil.. Lack of water.. Overheat
Seized piston / seized rod bearing AND/OR seized piston
If the piston can't go up, the force and weight of the crankshaft coming around causes the connecting rod to go horizontal.
Old tractors.. no warning buzzers or lights installed.
How many people actually drive their tractors with their eyeballs fixed on the oil pressure and water temp gauge?
The good news is you can purchase kit alarms online and install them yourself.
They have water temp and oil temp alarms buzzers and lights.
Had to install a kit on a boat engine I owned one time that had 'nothing'
Just some thoughts