What is a spun bearing?

Question

What does it mean to spin a bearing? I'm familiar with the location of these bearings and their function, as well as some of the causes and effects of a spun bearing. I just...don't know what it actually is.

Answer 1

There are two types of bearings, sleeve and ball (or roller). In each case, a spun bearing means the same thing, the bearing sleeve or ball race has attached itself to the shaft and the outer portion of the bearing is spinning in the bearing support structure. A journal sleeve bearing is a steel backing with babbit on the inner surface, keyed to the journal housing with a notch at the end of each half. Oil in the space between the babbit and the shaft provides the lubrication. If the bearing loses oil, it overheats, the babbit melts. The bearing will eventually cool enough for the babbit to solidify and stick to the shaft, and then the backing starts to spin in the journal support, a spun bearing. In the case of ball or tapered roller bearings, there is a "race" which keeps the balls or rollers in place. When lubrication is lost, the grease dries out or oil is lost, eventually the balls or rollers get hot enough to seize and freeze to the shaft, and then dragging the outer race along with the inner race and the balls or rollers, or the outer race stops the bearing and then the shaft spins inside the inner race, thus: a spun bearing. In either case, severe damage is done to the structure which supports the bearing. In the case of the sleeve bearing, like on a connecting rod, it means machining out the support and fitting a new sized bearing or as an alternative, machining out the damage and putting in a sleeve to correctly size the bearing support. The same goes for ball bearings, but ball bearings do not come in oversizes as connecting rod bearings do, so the only fix is to machine out room for a sleeve to make the bearing support the right size again. No matter how you look at it, a spun bearing is bad news, and only one word applies: expensive.

Answer 2

Spun bearing in what location? The engine? If you are referring to the engine it means the bearing halves(either connecting rod bearing or crankshaft main bearing) have rotated in there bores.
They are supposed to stay still in there bores (like a bearing race or cup) If they have spun, it means they have spun around either in the connecting rods big end (the part that spins on the crankshaft) damaging the connecting rod or in the crankshaft main bearing cap/bore damaging the engine block.

Answer 3

It is a term used to mean that a crank or main bearing has failed and is no longer attached ie it is now "spinning" around the shaft. This is a bit of a misnomer however because generally when it happens, most of the bearing ends up in shards in the oil pan

Answer 4

The bearing that is referred to is the bearing between the crankshaft journal and the connecting rod which is more of a bushing that is locked in place, when it gets spun is has turned inside the connecting rod causing damage to both the connecting rod and the crankshaft journal.

Answer 5

how much to repair you think on a 2000 toyota celica or in general estimated amount if can share or it may also involved other repairs ty appreciate it ( 2000 toyota celica auto 180xxx miles this car is really nice and was super reliable still can be it spun a bearing it still runs and drives good surprisingly does not over heat or anything crazy so will need to be rebuilt or just a new swap but literally everything else is awesome

Thanks thats what he has posted waiting to talk to him i can put some money into car but what would i truthfully if can share as i know could have other issues cuz of it now but how much if can say

Answer 6

the engine bearing is only a round metal piece two halves cover the crank or rod and the crank and rods float on oil.well if you run out of oil the bearing starts to spin with the crank,
thus the bearing is spun.i put a lot of thought into that for you tmo

Answer 7

There are two halves held together with an bearing end clamp/cap around the crank.

When 1/2 of the bearing slips around and doubles up on the other half of the bearing.

Answer 8

spun bearing is usually a rod or main bearing that is spinning inside the respective rod journal or main journal. They are not supposed to spin and after your bearing starts spinning, serious engine damage is usually not far behind.

Answer 9

the bearing that goes in between your crank shaft and pistons has kinda overlapped one another