UOA showed no indication of imminent cam failure

[saaber1]

Found this post where the UOA showed no indication of imminent cam follower failure despite obvious visible wear. I suppose it is hard to tell however how much of that wear occured before failure. I have seen lots of these follower pics as they wear and they get very thin before breaking like this one did, so certainly there was quite a bit of wear. Also the end of the fuel pumps (shown) show a lot of wear prior to breaking usually.

Originally Posted By: OOOO-A3
oil change every 5k since new, Castrol Syntec 5w40 VW 502.00.

Here's my Blackstone report. This oil sample was from before they did the repair, and I had been driving on it for quite a while so it was not 'sudden' as speculated by the Blackstone tech in the notes. Look at my pictures below.... if a Blackstone report won't pick up evidence of THAT, then it certainly won't pick up anything "before major failure".

I had the "B" (good) cam, too:

 

[ClarkB]

I'd consider putting the link in here somewhere. No one is going to want to look at it the way you have it set up.

Clark

 

[CharlieJ]

BuickGN has mentioned numerous times before that he has had a an engine fail yet a UOA did not show any detrimental sign of damage. I do not think UOAs are a very good indicator of engine wear. I see them as a good tool for knowing the condition that the OIL is in. It is called a Used OIL Analysis, not a Used ENGINE Analysis.

 

[Pablo]

Somebody posted the same thing in the same manner you did.

My 2 cents on this situation is two fold:

1) In some cases, when the wear is gradual or increasing, a series of UOA's can detect wear if you know what you are looking at.

2) In other cases, and in particular when a manufacturer relies on a certain level of (insufficient by design or manufacturing flaw) surface hardening on one or both contact/wear surfaces and that hardening goes bye-bye very quickly - that previous single "good" UOA didn't tell you diddly squat about the future.

 

[buster]

Unfortunately, oil analysis is a limited tool. Particle size limit of 3 to 5 microns, which means that particles larger are not detected. I've read that most serious wear issues generate wear particles in the range of 5 - 15 microns. Pablo's theory of little wear leads to bigger is a good one. Not sure if it's right or not. RL says otherwise.

There are other techniques such as ferrography, which looks at the wear particles under a microscope.

Quote:
From Roy Howell. The oils with the better spectrochemical numbers will be much less chemically active on the metal surface, so they will be less able to handle more severe loads. There is always a trade-off between chemical wear and adhesive wear. Chemical wear is the very small particles and soluble metals which is identified in the spectrochemical analysis, while adhesive wear is many orders of magnitude greater than the chemical wear, but much is not identified in spectrochemical analysis. But if you were using spectrochemical analysis as a maintenance tool and started seeing a deviation over the baseline, then you would know something was wrong.

 

[Chris142]

Gnarley

 

[wannafbody]

I'd think that the larger pieces would get caught by the filter and that's why it doesn't show up in a UOA.

 

[BuickGN]

Originally Posted By: wannafbody
I'd think that the larger pieces would get caught by the filter and that's why it doesn't show up in a UOA.



The large particles that don't show in the UOA can still be too small to get caught in the filter. I truly believe these are the ones that do the most wear.

 

[jshaw]

Wouldn't a UOA be at some level an indicator of an oil's ability to suspend particles. Could an oil lubricate very poorly and clean poorly and show a UOA that might not include all wear metals. In reading on this forum certain oils are said to be better at cleaning than others. Could a poor "cleaner" give a skewed indication of the contanimants present inside the oil system?

 

[03cvpi]

If that was the one and only UOA, it really means nothing other than the condition of the oil. We had an old chevy suburban we used for running at the plant. Company bought it new in 84 and it got about 10k of use each year. It got a regular OC at 3k and an UOA at every oil change. It was a 350cu with auto trans and from day one, it had high iron 10-12ppm even after break in. At about 60k the iron started creeping up from 12ppm to 18ppm. At 73k one of the pushrods punched through the bottom of one of the lifter. It still ran with a dead miss on one cylinder. We tore the engine down and found the lobes on the camshaft where almost flat and most of the lifters have a concave bottom. We rebuilt the engine and after about 15k of break in the iron dropped to 2-4ppm. We just sold it as a beater to one of the production guys for 300.00 with over 250k on the chassis and 180k on the engine, The last UOA had 4ppm iron. We use this as a an example of how just one UOA tells you very little, but a series will usually tell the tale. At 29ppm of iron on the sample shown, I would have been looking for something to fail on the engine. I generally ignore the universal averages, because what if 30 or 50 percent of those numbers come from an engine with a similar problem. If you are going to use a UOA to track engine wear start early and don't skip a sample. We use them at our plant for some really large and expensive pieces of equipment and they have helped to prevent what we call a creeping failure on several occasions, but there is still the catastrophic failure that may never show up in a UOA. Those have been few and far between.

 

[saaber1]

03cvpi, that is a great real-world example! I would have assumed large iron numbers with that kind of camshaft wear. Very interesting!

 

[SubLGT]

I like this quote from Polaris Labs website:

"If you depend solely on Elemental Analysis by ICP to detect wear metal concentrations, you may not always know when a catastrophic failure is in progress."

 

[SubLGT]

Here is another relevant quote, from Practicing Oil Analysis (Nov/Dec 2008);

"For instance, most people familiar with used oil analysis understand the limitations of elemental spectroscopy (ICP, rotating disc electrode, etc.) with respect to quantifying actual levels of particulate suspensions in used oils. Regardless of the type of spectrometer, particles larger than 10 microns are generally not measurable or are grossly understated in concentration. There have been many reported cases where this limitation led to “missed saves” when the limitations of elemental analysis were not compensated by other large-particle techniques such as particle counting, ferrous density analysis and patch testing.........."

 

[Liquid_Turbo]

Nice work.

 

[Gary Allan]

Originally Posted By: ClarkB
I'd consider putting the link in here somewhere. No one is going to want to look at it the way you have it set up.

Clark


You got that right. Way too much work to view it.

There's usually a "resize image for" (forums, message boards, web pages, emails, etc.) somewhere on most hosting sites.

 

[tdi-rick]

Has been noted in the past, and Doug Hillary frequently mentions the limitations of UOA's and component failures.

Here's one of my posts from 3.5 years ago http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Board=25&Number=587908

 

[Spector]

Which sort of supports the position that, for the average driver, it is less expensive to just change your oil then to pay for a UOA because, in reality, there is very little one can do to stop the wear and especially the catastrophic failures. Normal wear the engine will outlast the rest of the car, it is the catastrophic failures that are the problem.

 

[ADFD1]

Makes you lose faith in a UOA, aside from finding dirt or coolant leaks. I wouldn't put much faith in them for prevention of major failures.

AD

 

[tig1]

A friend has a 96 Ford Contour with 190,000 miles and a lifter just broke. He pulled the cams to make the repair and found they were in great shape, no sign of wear at all. Many here worry about M1 5-30 causing cam wear, but that's the only oil used in his engine. A few PPM means nothing as far as engine failure in most cases. UOAs are are not much value for the average person as I see it, except perhaps if a coolant leak is supected or other rare failures.

 

[ADFD1]

I feel the same way, dirt or a coolant leak and not too much else for the average guy.

AD