What exactly happens when a bearing goes bad?

[Omahaug]

I know what bad bearings look like, what is the failure mode though?

For example if a bearing is bad or damaged, is it guaranteed to progress to total failure? Would you be guaranteed to see an increase in metals in a used oil analysis?

Conversely if you see little to no wear metals in a used oil analysis can you positively state that your bearings are happy?

Is it possible for bearings to be damaged but the damage to not cause an impact? For example if a particle streak occurs, what does it actually translate to? Does it translate to decreased engine life span? Why? Does it leave things unchanged? Why? Does the fact that it streaked cause progressive wear?

 

[ZeeOSix]

All kinds of ways engine bearings can go bad.

http://www.agkits.com/bearing-failure-analysis.aspx

https://www.pioneer-engineering.com/resources/main-bearing-failure-modes

 

[Linctex]

Originally Posted By: NoNameJoe
I know what bad bearings look like, what is the failure mode though?

Bearings can wear slowly over time, Fail dramatically within seconds....or anywhere in-between.

Originally Posted By: NoNameJoe
For example if a bearing is bad or damaged, is it guaranteed to progress to total failure? Would you be guaranteed to see an increase in metals in a used oil analysis?

No, not necessarily. I've torn down good running engines with excellent oil pressure that had bearings worn all the way through the white metal and WELL into (and sometimes past) the copper plating. These were typically engines that led a "Mostly" easy life and interrupted occasionally by severe duty (like pulling a heavily loaded moving trailer cross country every 2 years)


Originally Posted By: NoNameJoe
Conversely if you see little to no wear metals in a used oil analysis can you positively state that your bearings are happy?

Theoretically, that sounds reasonable and logical.

 

[Donald]

I think Blackstone likes to say "particle streak" when they cannot find anything else to blame. I guess it's very rare.

If you see lead or copper in UOA something is going on. An oil cooler can cause higher copper but lead is pretty much a bearing.

 

[BrocLuno]

Originally Posted By: Donald
I think Blackstone likes to say "particle streak" when they cannot find anything else to blame. I guess it's very rare.

If you see lead or copper in UOA something is going on. An oil cooler can cause higher copper but lead is pretty much a bearing.


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