What exactly is a "spun" bearing?

[douglas vincent]

Just so I know, thanks

[vrg3]

I believe it's just when a bearing rotates in place. Ordinarily, a shaft rotates inside a bearing, with an oil film between the shaft and the bearing. The oil comes in through a hole in the bearing. Once the bearing is spun, the interface no longer gets the lubrication it needs.

I've never torn down an engine or examined the bearings of a motor before, though, so someone correct me if I got it wrong.

[mTk]

That's correct vik. W/ the rod bearings the oil comes through the crank.

MK

[BAC5.2]

Yea, the bearing will actually spin in it's location.

If you spin a rim inside a tire, that's what SHOULD be happening with the bearing. If the tire gets traction and spins slightly, that's what happens when you spin a bearing.

It usually leads to the engine seizing. Bearings should stay in place.

[magicmike]

just to clarify...the oil comes in through a hole in the journal (main or pin) not the bearing, if we are talking about crankshaft bearings anyway.

-Mike