To me it looks wear lead to a major failure and some chunks breaking off. I'm pretty sure a good machinist could tell exactly what went wrong and why. I'm a little surprised myself the UOA didn't show hints of the problem.
UOA showed no indication of imminent cam failure
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Originally Posted By: demarpaint
I'm a little surprised myself the UOA didn't show hints of the problem.
I'm not surprised myself as it's a common knowledge that UOA does not estimate wear very well. Magnetic particle weight in filter does and magnetic drain plug analysis is another simple technique.
This is a good primer on magnetic plugs:
http://www.noria.com/learning_center/cat...roup=WearDebris
I'm a little surprised myself the UOA didn't show hints of the problem.
I'm not surprised myself as it's a common knowledge that UOA does not estimate wear very well. Magnetic particle weight in filter does and magnetic drain plug analysis is another simple technique.
This is a good primer on magnetic plugs:
http://www.noria.com/learning_center/cat...roup=WearDebris
23 ppm of Iron in a 5k mile OCI sure would have been a warning sign to me. UOA's are not a panacea, especially since they miss any large particles. A lifter bucket falling apart like the one in question was certainly shedding a lot of big stuff.
Put another way, what do you expect for $25 worth of testing and analysis?
Put another way, what do you expect for $25 worth of testing and analysis?
This is what I've been posting about. Two engine failures, worn in the worst possible way, about 8 UOAs between the two and only one showed slightly elevated but single digit lead. In other words the UOA caught nothing even though every surface in the engine was toast.
Anyone know VOA of Castrol HD 30wt mono-grade?
I have looked and can't find it anywhere. Even a UOA would be some information.
Castrol won't give out this information.
JimPghPa
I have looked and can't find it anywhere. Even a UOA would be some information.
Castrol won't give out this information.
JimPghPa
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This supports what Doug Hillary has been saying since the beginning FWIW.
Originally Posted By: BuickGN
This is what I've been posting about. Two engine failures, worn in the worst possible way, about 8 UOAs between the two and only one showed slightly elevated but single digit lead. In other words the UOA caught nothing even though every surface in the engine was toast.
I hear what ur saying but I should clarify that we are talking about failure of one specific part, the cam follower, which is smaller than a thimble. Related parts that also wear due to the failure are one lobe of the intake camshaft (this lobe is for the fuel pump) and the tip of the high pressure fuel pump, which sits outside the engine (all parts are shown in the photos). Not arguing against your point, just clarifying that wear is from those parts. No indication that the small metal bits did damage elsewhere but who knows for sure really.
This is what I've been posting about. Two engine failures, worn in the worst possible way, about 8 UOAs between the two and only one showed slightly elevated but single digit lead. In other words the UOA caught nothing even though every surface in the engine was toast.
I hear what ur saying but I should clarify that we are talking about failure of one specific part, the cam follower, which is smaller than a thimble. Related parts that also wear due to the failure are one lobe of the intake camshaft (this lobe is for the fuel pump) and the tip of the high pressure fuel pump, which sits outside the engine (all parts are shown in the photos). Not arguing against your point, just clarifying that wear is from those parts. No indication that the small metal bits did damage elsewhere but who knows for sure really.
If UOAs can't predict an imminent failure--and obviously they can't be counted on for that--can they still be an indicator of the rate of long term normal wear, say, to campare between two different oils?
Like, hypothetically if an engine is going to go 300K miles with oil A and 200K miles with oil B, do you think there would be a different average metal content on the UOAs?
Since there is a "normal" metal break-in curve as shown above, this would seem to be the case.
Thoughts?
Like, hypothetically if an engine is going to go 300K miles with oil A and 200K miles with oil B, do you think there would be a different average metal content on the UOAs?
Since there is a "normal" metal break-in curve as shown above, this would seem to be the case.
Thoughts?
Not really. There are so many factors affecting engine life not to mention margin of error you really cant. Its basically for checking the condition of the oil. Some times though you will see things like coolant contamination flagged along with wear metals rising or silicon (dirt) going up along with metals. This is where trending helps so you have a baseline of what should be going on so you can catch stuff like this.
I see.
BTW, I periodically look for silver swirls in the used oil and drag a magnet through it.
I had an aluminum cased oil pump getting slowly ground up by the camshaft in a VW van...over a period of about 20K miles. I couldn't figure out why the oil always had silver swirlies in it until I replaced the pump for other reasons and saw the cam side of it. Swirls are gone now.
So I guess that was a good indication of wear in my case. However, the reason I replaced the pump was to put a filter set-up on.
I'll never know if the filter would have caught all that visual metal or not--my guess is it would not have gotten all of it.
BTW, I periodically look for silver swirls in the used oil and drag a magnet through it.
I had an aluminum cased oil pump getting slowly ground up by the camshaft in a VW van...over a period of about 20K miles. I couldn't figure out why the oil always had silver swirlies in it until I replaced the pump for other reasons and saw the cam side of it. Swirls are gone now.
So I guess that was a good indication of wear in my case. However, the reason I replaced the pump was to put a filter set-up on.
I'll never know if the filter would have caught all that visual metal or not--my guess is it would not have gotten all of it.
Makes you wonder whether you might have learned more about the possible failure had you passed on the UOAs and spent some time on a model-specific website instead.
Your's could be a one-off failure, but I doubt it.
Also, could Terry Dyson have been of any help?
I plan on getting a Dyson analysis of the second run of GC from the Sube.
Expensive, but the interpretation is of more value than the test results, IMHO.
Your's could be a one-off failure, but I doubt it.
Also, could Terry Dyson have been of any help?
I plan on getting a Dyson analysis of the second run of GC from the Sube.
Expensive, but the interpretation is of more value than the test results, IMHO.
Originally Posted By: fdcg27
Makes you wonder whether you might have learned more about the possible failure had you passed on the UOAs and spent some time on a model-specific website instead.
Your's could be a one-off failure, but I doubt it.
Also, could Terry Dyson have been of any help?
I plan on getting a Dyson analysis of the second run of GC from the Sube.
Expensive, but the interpretation is of more value than the test results, IMHO.
Those two examples I posted are not my cars. They are not one-off failures, somewhat common. I maintain a database of UOAs for this engine that has over 45 UOAs (see graph above). The second example I posted clearly showed something wrong prior to cam follower issue. The first one I posted showed nothing.
Makes you wonder whether you might have learned more about the possible failure had you passed on the UOAs and spent some time on a model-specific website instead.
Your's could be a one-off failure, but I doubt it.
Also, could Terry Dyson have been of any help?
I plan on getting a Dyson analysis of the second run of GC from the Sube.
Expensive, but the interpretation is of more value than the test results, IMHO.
Those two examples I posted are not my cars. They are not one-off failures, somewhat common. I maintain a database of UOAs for this engine that has over 45 UOAs (see graph above). The second example I posted clearly showed something wrong prior to cam follower issue. The first one I posted showed nothing.
I'm of the opinion that the failure of fuel pump's cam-follower on the FSI should not take as a guage on the effectiveness of UOA. I'm sure more of such failure will happen.
It is a component that seem quite definate to wear out (call it design failure if you wish) and its particals will be seen in the UOA as acceptable trend. It will eventuall fail of fatigue which, again, will not show any symptom when the crack propagation may have already initiated.
As far as I see it, it will be best to replace the cam-follower every 30k miles or 50k km.
Just this helps.
It is a component that seem quite definate to wear out (call it design failure if you wish) and its particals will be seen in the UOA as acceptable trend. It will eventuall fail of fatigue which, again, will not show any symptom when the crack propagation may have already initiated.
As far as I see it, it will be best to replace the cam-follower every 30k miles or 50k km.
Just this helps.
Originally Posted By: autoreign
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.
Very good post Clement I totally agree. This was a sudden failure which could not have been detected in advance by any kind of oil analysis, including particle count.
Originally Posted By: ADFD1
Those parts wore out, they didn't fail immediately. Regular UOA's probably wouldn't have detected the parts wearing out I think is the real point of this discussion.
ADFD1 - you are dead wrong. This was obviously a sudden failure, followed by some major damage, not a case of gradual wear.
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.
Very good post Clement I totally agree. This was a sudden failure which could not have been detected in advance by any kind of oil analysis, including particle count.
Originally Posted By: ADFD1
Those parts wore out, they didn't fail immediately. Regular UOA's probably wouldn't have detected the parts wearing out I think is the real point of this discussion.
ADFD1 - you are dead wrong. This was obviously a sudden failure, followed by some major damage, not a case of gradual wear.
Originally Posted By: mva
Originally Posted By: autoreign
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.
Very good post Clement I totally agree. This was a sudden failure which could not have been detected in advance by any kind of oil analysis, including particle count.
Thank you mva. I am gaining a lot from here and this is just a bit of my contribution.
Originally Posted By: autoreign
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.
Very good post Clement I totally agree. This was a sudden failure which could not have been detected in advance by any kind of oil analysis, including particle count.
Thank you mva. I am gaining a lot from here and this is just a bit of my contribution.
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