* Scuffing and scoring of cylinder walls: The pistons, constantly rubbing against the cylinder walls, will create deep scratches and gouges. This severely reduces compression and leads to power loss and blow-by (combustion gases escaping past the pistons).
* Seized bearings: The crankshaft, connecting rods, and camshaft all rely on oil to keep their bearings lubricated. Without oil, these bearings will overheat, melt, and seize, locking up the engine completely. This is often the most immediate and devastating type of damage.
* Damaged crankshaft: The lack of lubrication can cause the crankshaft to bend or break.
* Damaged camshaft: The camshaft, responsible for operating the valves, will suffer similar damage to the crankshaft, leading to valve timing issues or complete failure.
* Destroyed piston rings: The piston rings, crucial for sealing the combustion chamber, will wear down extremely rapidly and likely break.
* Valve damage: The valve lifters rely on oil, so those could seize up causing valve damage or even breakage.
* Oil pump damage: While seemingly counterintuitive, even the oil pump itself may suffer from lack of lubrication, further compounding the issue.
In short, running an engine without oil is almost always a total engine failure event requiring a complete rebuild or replacement. The damage is often so extensive that repair costs far exceed the value of the engine.
