Will metals always be elevated if bearing bad?

[LM]

If a failing conrod or main bearing, camshaft wear, etc., is causing engine knock (understanding knock can be multi-causal and mis-diagnosed), will metals always be elevated in the UOA if it's been going on for a couple thousand miles/km?

If just a single UOA is used, vs trend-analysis, would the numbers have to be substantially elevated? Thank you

 

[buster]

Hard to say. Guy's at RL have told me that they have sampled oil from engines that have blown, but the levels were very low. It's a good question. Oil analysis has it's limitations.

 

[buster]

Quote:

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Race teams will use observation and comparative measurements to determine engine wear and relative lubricant performance. Oil analysis has typically been used by fleet operators to follow trends, to determine reasonable drain intervals and spot abnormal conditions that might indicate an impending failure. Teardowns are certainly superior for comparing and determining wear. Oil analysis only looks at very small particles, gross levels from a component failure can be difficult to spot.

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[ATS-V]

I think it depends on the failure type.

In the LM's example I think you'll always see elevated levels. If the levels are very, very low I would suspect sudden failure such as a broken rod.