I don't disagree with you Zee, and I clearly made statements of qualification that said not all UOAs will catch all problems. Unless I misunderstand you, you would probably agree that UOAs are not infallable, but they certainly improve the odds of finding a problem. They are not 100% able to find all issues, but they are also not worthless in finding issues.
This is what I have a problem with; I take exception and disagree when kschachn says this:
Taken in context, that is a statement of finality; a claim that is absolute, without qualificaiton of exemptions. The inference being that UOAs would never find "real damage" as it develops. That statement is 100%, without any doubt, wrong; I linked a path to see where MANY UOAs did indeed find or confirm real damage as it was happening as proof that his statement is wrong.
TiGeo's example is fair and just; UOAs didn't catch his issue. But there are plenty of examples from Blackstone's Newsletters which show problems were discovered in UOAs that never manifested elsewhere, or proceeded discovery by other sensory means. The point being, UOAs work well some of the time, but not all time. However the same can be said of other analysis tools; they occasionally miss stuff too.
Finding equipment problems is a function of how hard you look, how often you look, and what tools you look with. Using UOAs will not assure you that you'll discover a problem, but they are most certainly proven to improve the odds of finding a problem. Here's what we can do to find an equipment problem ...
- look for visual clues (leaks and other abnormalities)
- listen for audible clues (clunking, grinding, squeals, chirps and other abnormalities)
- feel for tangible clues (vibration)
- analyze with high-tech tools (thermal sensing guns, non-primary-order vibration sensors)
- do UOAs to track your unique equipment history and compare/constrast against known "good" examples (wear metal abnormalities)
- track fluid consumption (loss, or transfer of lube and coolant for example)
Some of these are outside the cost and skill levels of the average Joe. But some are easily done in the garage at home. UOAs are not the only means of finding "real damage"; they are but one of several. UOAs work well; not always, but often enough to make them one of the viable tools to find problems. UOAs also offer a distinct advantage in that they are objective and not subjetive. They are also relatively inexpensive relative to other costs such as uber-expensive high-tect tools or engine tear-downs. As you add "tools" to your analysis, you improve the likelihood that you'll discover problems as they develop. It's not that you can be 100% sure; it's much more akin to simply improving your odds of accuracy. UOAs are not going to be without error at all times, but they are also not 100% worthless either. At times, they will be the lead indicator, other times not. That is true of all those "tools" above.
I believe that kschachn's statement is incorrect because it misleads one in a path of totality, as if UOAs can never find real damage. That is utterly wrong; UOAs are proven to find real damage. Just not all the time.
