I use UOA's for make buy decisions on keeping or buying vehicles at what I call the "turning point" (120-150k miles). Most of the time I am looking for unusual wear metals and coolant. Since coolant leaks are fairly common and go undetected by most people until they do permanent damage, a uoa for coolant is a big help in deciding to not buy or trade in a vehicle that is at the turning point in it's life. I won't buy a used car without a UOA/Carfax/complete check by my mechanic. You wouldn't believe the "duds" I have uncovered for friends when shopping for a used car. The whole process costs aboout $250 and is definitely worth it. After doing this for several years now I have come to believe that 3/4 of the used cars out there have some major repair issue waiting to happen.
UOA showed no indication of imminent cam failure
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Originally Posted By: Gary Allan
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.
This is a little easier to read, but still too wide
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. (EDIT FOR CLARITY: I changed the oil @ 50,000. Discovered the failure at ~53,500. Continued to drive the car with a new follower until 55,xxx when the dealer replace the cam, follower again, and pump. I drained a sample of oil for the analysis the evening before I took it in for the repair. Who knows when the actual failure took place, but this particular sample of oil had been in the engine for 5000 miles of metal-grinding action.)
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:
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.
This is a little easier to read, but still too wide
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. (EDIT FOR CLARITY: I changed the oil @ 50,000. Discovered the failure at ~53,500. Continued to drive the car with a new follower until 55,xxx when the dealer replace the cam, follower again, and pump. I drained a sample of oil for the analysis the evening before I took it in for the repair. Who knows when the actual failure took place, but this particular sample of oil had been in the engine for 5000 miles of metal-grinding action.)
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:
Quote:
I suppose it is hard to tell however how much of that wear occured before failure.
Exactly.
If between 10 - 30k miles, the oil was never changed and was basically run dry, trashing the engine, it wouldn't show up on a current UOA where the engine now has good oil and is wearing well. This is basically an "after-the-fact" UOA where a couple of oil changes have flushed out the excess wear particles. So one can't conclude from this that a UOA wouldn't have caught the high levels of wear.
It's takes some pretty serious neglect of the oil to get that kind of damage on an engine with the generally high quality oils we have these days.
I suppose it is hard to tell however how much of that wear occured before failure.
Exactly.
If between 10 - 30k miles, the oil was never changed and was basically run dry, trashing the engine, it wouldn't show up on a current UOA where the engine now has good oil and is wearing well. This is basically an "after-the-fact" UOA where a couple of oil changes have flushed out the excess wear particles. So one can't conclude from this that a UOA wouldn't have caught the high levels of wear.
It's takes some pretty serious neglect of the oil to get that kind of damage on an engine with the generally high quality oils we have these days.
Any pictures of the cam follower ?
It may be related to a stress fracture (sudden failure) and not wear related.
It may be related to a stress fracture (sudden failure) and not wear related.
Cam follower is the broken piece shown above. All the black coating is worn off and there probably was quite a bit of material gone judging by photos of other cam followers that have been posted. This should have been checked at least twice prior to failure at 53.5k. It is a known weak spot. Generally indicators before failing can be black coating worn off, cupping (concavity) of follower surface, and even cracks form one oil hole to the next. Failure generally occurs along those cracks.
f.e. as posted in a UOA thread:
good:
bad:
f.e. as posted in a UOA thread:
good:
bad:
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How in the world can someone not hear/see/feel that the engine has major problems with parts that bad in it?
Originally Posted By: 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.
or filter cut-ography, filter should catch most particles larger them 10 microns
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.
or filter cut-ography, filter should catch most particles larger them 10 microns
hm this is what most UOA's lack..particle count by size:
I am doing my next UOA with Polaris labs since they do particle count.
I am doing my next UOA with Polaris labs since they do particle count.
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Judging by the look of the Cam-follower, it would seem to me that it suffered a fatique failure (Crack and propagate from four tiny holes on the cam follower), not by way of surface wear and therfore would not show much information on UOA before failure.
(Extract from wikipedia: fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. visit http://en.wikipedia.org/wiki/Fatigue_%28material%29 for more detail).
The posible reasons of such failure are as follows:
1) Initial scratch on the cam-follower which caused an usually high stress on the cam-follower. Change your oil to, perhaps, VW 504.00/507.00 compliance oil which offers v high wear resistance when metal are in contact.
1a) Contamination in oil. Select oil with low soot formation, good resistance to oxidation, low piston ring deposit, and good oil film thickness to provide better seal (less blow-by). Again, VW 504.00/507.00 is an excellent oil in this context. Alternatively shorter OCI.
Additional information: Generally, thinner oil provide better seal unless on extreme driving condition such as track day. Oil film thickness is viscosity and load related. Low to mid load - low viscosity oil provide better oil film thickness. High load - higher viscosity oil provide better oil film thickness. (Sorry, don't remember where I read this from. Anyway, it is a thesis from a university).
2) Extreme load on the cam follower. This could be caused by high fuel pressure when you throttle off and fuel pump is still running (fuel, being liquid, is incompressible). Replace your fuel pressure limiting valve which allows the excess fuel to flow back to fuel tank.
2a) Resistance in cam-follower movement. Your housing, where the cam-follower is seating, seem scratched. Bore or replace housing.
3) Cam-follower failure seem common in FSI engine. Change Cam-follower every 30,000 mile or 50,000 km. (Guess work but based on statistic although limited).
Hope this helps.
Cheers,
Clement
(Extract from wikipedia: fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. visit http://en.wikipedia.org/wiki/Fatigue_%28material%29 for more detail).
The posible reasons of such failure are as follows:
1) Initial scratch on the cam-follower which caused an usually high stress on the cam-follower. Change your oil to, perhaps, VW 504.00/507.00 compliance oil which offers v high wear resistance when metal are in contact.
1a) Contamination in oil. Select oil with low soot formation, good resistance to oxidation, low piston ring deposit, and good oil film thickness to provide better seal (less blow-by). Again, VW 504.00/507.00 is an excellent oil in this context. Alternatively shorter OCI.
Additional information: Generally, thinner oil provide better seal unless on extreme driving condition such as track day. Oil film thickness is viscosity and load related. Low to mid load - low viscosity oil provide better oil film thickness. High load - higher viscosity oil provide better oil film thickness. (Sorry, don't remember where I read this from. Anyway, it is a thesis from a university).
2) Extreme load on the cam follower. This could be caused by high fuel pressure when you throttle off and fuel pump is still running (fuel, being liquid, is incompressible). Replace your fuel pressure limiting valve which allows the excess fuel to flow back to fuel tank.
2a) Resistance in cam-follower movement. Your housing, where the cam-follower is seating, seem scratched. Bore or replace housing.
3) Cam-follower failure seem common in FSI engine. Change Cam-follower every 30,000 mile or 50,000 km. (Guess work but based on statistic although limited).
Hope this helps.
Cheers,
Clement
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This is where trending comes in. Unlike commerical stuff few of us do a UOA on every oil change. I can guarntee that if this car had a UOA every oil change of it's life when the accelerated wear started it would have been easy to see somethinginthe valve train was wearing badly. Right before the failure though often the their is nothing to wear interms of contact point as it has already been worn tothe point it is no longer making good contact...Then it is just a matter of time until in it's eakened state it fails completly from a stress crack!
UOA is not that great of a tool unless you do it regularly to establish trending paterns!
UOA is not that great of a tool unless you do it regularly to establish trending paterns!
Wow and a synthetic 40 grade oil to boot, glad a 20wt wasn't used
j/k. Unless you're doing a UOA every oil change I doubt they're going to be useful in averting an engine failure. Even then I have my doubts about them. Still not seeing the value in them, sorry guys.
Why would a uoa show anything about an imminent failure of any kind? It is like saying syn oil will make a trans last longer if the trans failures are from breaking parts.
The fact that one of the visual methods of checking for bad lifters is cracks tells me it probably broke. You are not going to see that type of stuff in a UOA. It almost makes me wonder if there is not enough spring so the lifters are getting thrown off the lobe (float) and getting hammered like that. But I am by no means an expert.
Originally Posted By: zoomzoom
...
I am doing my next UOA with Polaris labs since they do particle count.
At $28 for the "advanced" these guys seem to offer the most bang for the buck ...
...
I am doing my next UOA with Polaris labs since they do particle count.
At $28 for the "advanced" these guys seem to offer the most bang for the buck ...
big time valvetrain design defect on that engine....
Here is a counter example of the same engine with exactly the same problem where a UOA clearly showed something wrong:
QUOTE=corradokidg60...Here's my Blackstone oil analysis for 40k miles worth of changes (4) - the last oil change shows metals in it because I later found out I had the dreaded HPFP/intake cam/cam follower wear issue.
QUOTE=corradokidg60...Here's my Blackstone oil analysis for 40k miles worth of changes (4) - the last oil change shows metals in it because I later found out I had the dreaded HPFP/intake cam/cam follower wear issue.
saaber1 said:
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Wow. the information on this thread flow really fast.
Thanks for all the great info.
Thanks for all the great info.
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