Spun bearings - Maintenance and Repair Forum

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Spun bearings
Wednesday, April 13, 2005 5:38 PM
My friend thinks he may have spun a bearing. I've never had this happen to me or any of the other cavs I know of. Care to explain what this is and how I can tell if he's spun a bearing?

(personally I think it's just his power steering making noise but hey.... what do I know)

Re: Spun bearings
Wednesday, April 13, 2005 5:42 PM
There are bearings that support the crankshaft as it spins, and these can break by spinning out of their journals (metal to metal contact) or say if theres improper oiling it wears down making the bearing useless. The bearing is on the bottom of the piston connecting rod and it kind of rides around on the crankshaft as it spins.. when a bearing is "spun" it means its all worn out and the connecting rod no longer can rotate correctly on the cam, so it knocks all around the crank journal and will have a lot of play in it..




Re: Spun bearings
Wednesday, April 13, 2005 5:48 PM
Thanks I'm gonna take a look into it this weekend. he said he wants to take it to a professional. just got off the phone with him.

So much for friendly advice.
Re: Spun bearings
Wednesday, April 13, 2005 6:28 PM
If he spun a bearing, you would definitely know it. It sounds like someone is hitting the block with a hammer. It is loud as shiznit.




-da chinchilla

<img src="http://registry.gmenthusiast.com/images/jiggamon/avatar15569_2.gif">
Re: Spun bearings
Wednesday, April 13, 2005 6:51 PM
sorry to jack the thread, but when a bearing is spun, what gets damaged other than the bearing? Does the crank/block get damaged?
Re: Spun bearings
Wednesday, April 13, 2005 7:04 PM
depends on what breaks...sometimes you can get away with just replacing the spun bearing..but most times, when the bearing goes, it scores the journal of the crankshaft...usually you have to replace the crank, the connecting rod, and the bearings.. if you go too long with a spun bearing like i did in a toyota tercel i had, the connecting rod broke at the crank and blew a hole in the side of the block.



Re: Spun bearings
Thursday, April 14, 2005 5:13 AM
If you just replace the bearing, it will spin again, because it wears the crank and rod itself, so it will just wear the new bearing. If you spin the bearing, you must take the rods and crank to the machine shop to have them checked and turned. Then purchase an undersized bearing. For example if they take 0.010" off the crank journal, you must purchase a 0.010" undersized bearing. (it is referred to as undersized, because the rod journal on the crank is now smaller than it was previously).

That is the best case. Worst case, the bearing breaks into pieces, the rod binds on the crank, breaks, and goes through the block, or the oil pan. Not pretty.




-da chinchilla

<img src="http://registry.gmenthusiast.com/images/jiggamon/avatar15569_2.gif">
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