What Happens To An Engine Without Oil?

in this video we’re going to be discussing what happens when an engine has no oil. As a demonstration, we’ll be viewing an engine with and without oil running. This is the exact same engine on the left and the right, on the left with oil, and on the right without. Both engines will start at the exact same time, but the video on the right was filmed 24 hours after the video on the left, allowing for the engine to completely cool. This is a 212 cc air-cooled single-cylinder Harbor Freight engine.

There are five points we’re monitoring on each engine. Point one is the crankcase, below the level at which oil will rest. Point two is the top of the crankcase, where there obviously won’t be any oil resting near. Point three is the air-cooled cylinder bore. Point four is the exhaust pipe exiting the cylinder before entering the muffler, and point 5 is the valve cover. This is a pushrod style valve train with overhead valves.

Opening the crankcase reveals the permanent damage which occurred. First of all, look at the small amount of oil that didn’t quite make it out while draining. It’s quite dark, and this is after a 15 minute run with oil, and 15 minutes without, in a brand new engine. The oil which remained in the drained engine is clearly quite dirty, and actually it has quite a bit of metal content in it, as you can see reflecting as I move around the towel.

Examining further, I removed the connecting rod cap from the crankshaft. This is the bearing the crank rotates on. You can see the scored, less reflective surface of the cap. Indeed, you can see the scratches on the crankshaft as well. I would expect to see similar issues with the camshaft and cylinder bore as well.