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 Post subject: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<<
PostPosted: Wed Jan 02, 2019 5:20 pm 
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VALVE REPORT IS IN!

Sorry that this took so long, this appears to be a graduate thesis - which fits with my understanding that graduates would be working on this for us. I am just reading through the file myself, so we all get to learn at the same time.

https://filedn.com/l66QmOFvA1PmdSNSgvL0 ... Report.pdf

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 7:06 pm 
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Thanks geordi!!!

My take aways after reading:


A notable decrease in diameter, therefore material loss, in the used specimens is most likely a result of wear. This can occur when combustion products and particulate matter accumulate between the valve and the valve seating and cause abrasion.

As a general trend, the grains at the center of the used and broken specimens are coarse relative to the new specimens, with a larger average diameter. This is most likely a result of prolonged exposure to high temperatures during service up to 660 °C causing grain growth.

A future inspection of the exhaust gas recirculation (EGR) equipment may provide further evidence for the cause of this shortened valve life.

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 Post subject: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<<
PostPosted: Wed Jan 02, 2019 7:58 pm 
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vwroad87 wrote:
Thanks geordi!!!

My take aways after reading:


A notable decrease in diameter, therefore material loss, in the used specimens is most likely a result of wear. This can occur when combustion products and particulate matter accumulate between the valve and the valve seating and cause abrasion.

As a general trend, the grains at the center of the used and broken specimens are coarse relative to the new specimens, with a larger average diameter. This is most likely a result of prolonged exposure to high temperatures during service up to 660 °C causing grain growth.

A future inspection of the exhaust gas recirculation (EGR) equipment may provide further evidence for the cause of this shortened valve life.


What do people see for EGT’s on the stock turbo at low RPM/high load? Like climbing a steep hill in 5th?

I never had a gauge installed on my stock turbo, but with DieselGuys GTB2056 installed, I cannot get over 1100*F unless I’m absolutely foot to the floor and 3500+ rpm. That’s running a lot of pressure at high altitude with fueling to match.

Cruising at freeway speeds im ~800*F.

I guess what i am getting at is I wonder if this is another issue related to emissions. You put a restrictive turbine on the engine to promote EGR function, but it has the side effect of increased EMP’s and EGT’s. Perhaps this is simply an issue of an engine designed for less strict emission standards being shoehorned in.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 8:57 pm 
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TURBO-DIESEL-FREAK wrote:
geordi:

Please make this a "sticky".


The request has been submitted. I'm not an admin, so I can't add or remove stickies myself. Only request them, but I do agree that this is of significant value to the group.


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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 9:41 pm 
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shocking departure from accepted scholarly authorship on
page 21 of linked report -diameter of surveyed valve stems noted in inch notation--

valves of course--are fabricated to metric nominal standards--
and global scholarly journals are Système international anchored


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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 9:46 pm 
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Sorry about the delay on this report. It slipped my mind a year ago, and Geordi and I lost touch. My CRD has been running well besides an electronic transmission problem, so I haven't been checking in here lately. The samples for this report were provided by Geordi, my students did the lab work, and I supervised and funded the project. This represents over a years worth of work in the lab, and a ton of money in characterization costs. I am happy to discuss the results but the conclusions represent what we discovered in this project. So, you can cut to the conclusions for the short version of our findings. These findings will not support any sort of action against VM Motori or Chrysler, that was not the intent of this investigation. No armchair metallurgists need to comment unless you have something compelling and defend-able to add.

Enjoy

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 9:47 pm 
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pulsenpal wrote:
shocking departure from accepted scholarly authorship on
page 21 of linked report -diameter of surveyed valve stems noted in inch notation--

valves of course--are fabricated to metric nominal standards--
and global scholarly journals are Système international anchored


Yep, you got us. Great input.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 10:11 pm 
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To put this work in context, this was an undergraduate senior design report that spanned over one year of work. I did not tally the amount of time and money that we spent on characterization, but it was huge, and if this work were to be done by a consulting firm, the cost would be crazy. Certainly more than a few CRDs are worth. Furthermore, the report is the final report as received from the students. If you hunt and peck, you are bound to find some errors as mentioned above. This was an internal document, and as such, I did not comb through it and make revisions as I would on something submitted to a peer-review archival journal. The students did a really good job on this document, and I think the conclusions represent the findings, and give the CRD owner some insight to their engine, it's longevity, and help to formulate an opinion about the amount of time, energy, and money that one might want to put into keeping a high mileage KJ CRD on the road.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 10:24 pm 
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Jerry (Dent) - I didn't know if you wanted direct credit for all of this, so please accept my apologies if it seems like I was leaving you out of it. There has been a fair amount of "noise" that I have been hopefully successful in shielding you from about this.

That said, I am extremely grateful for your work and testing on these, the information may not be anything actionable against VM, but that was NEVER a goal of mine anyway - knowing that it would never go anywhere with them at all. But your gift of information to the community has been amazing, now each owner just has to decide where they want to go with the information for themselves.

The only credit I will accept for myself is being the public face of the project and a set of semi-skilled hands collecting and forwarding the dead parts for cataloging and evaluations. ALL the credit goes to Jerry and his students.

THANK YOU SO MUCH!!!

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 11:43 pm 
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Well thought out & written report.
Its great to see our future technical specialists getting real world problem experience.
There is no mention that this report is for the ENR engine. There were significant head changes made by VM for the ENS engine that followed. With the introduction of this & newer CRD technology ( paiseo injection) we may have seen VM overcome the problem. I have not heard of similar failures with the ENS engine. I don't know if they used the same valves in the ENS engine.

These are standard exhaust valve alloy. I suspect that more severe service alloys may be available. Can anyone comment?
Having to replace exhaust valves before 150k miles is not what one would expect in a car engine. In other industrial diesel engines this would be seen as way too low. There are Mercedes diesel engines in cars that have done over 1,000,000 miles without requiring such work. I wonder what is the situation with the new 2 litre Bi turbo diesels being used by Ford & VW. They may be keeping EGT's down with injection programing?
Sorry for all the questions.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Wed Jan 02, 2019 11:46 pm 
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Thank you Dent for your help in this wonderful report and Geordi for your contributions to this effort.
Does appear from studying the detailed report that loss of some mass in the critical failed area may be a contributing factor which kinda reaffirms my belief that EGR operation with it's soot injection into the combustion process may contribute to possible erosion or exfoliation of the valve stem material over the life of engine.

Other possibility is the valve stem stretching due to cyclic life in the critical exposed area to the hot exhaust exit gases which could cause a decrease in stem mass over time.
Unfortunately the report did not report or compare valve overall length of new versus used exhaust valves.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Thu Jan 03, 2019 12:51 am 
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No offense taken Geordi. We enjoyed working on this project, and the students learned a lot from it. It was one of the better group project from that year, and they did a lot of work.
Thanks for working with them, and thanks for the help with my CRD when you were here in CO working your magic. As I mentioned on the FB page, if my Jeep gets to 200k miles, I'll be calling on you to come out for a head swap. I'm at 125k, and I feel I'm on borrowed time. I wish the report was even more definitive, but I don't think we are going to see many of these KJ CRDs making 300k miles without exhaust valve intervention. Also, the students should not have referred to the later VM Motori 2.8 engines used by GM. Those that did some literature review got ahead of themselves.
We only looked at 2005-2006 Jeeps, as you know, but someone mentioned above.

geordi wrote:
Jerry (Dent) - I didn't know if you wanted direct credit for all of this, so please accept my apologies if it seems like I was leaving you out of it. There has been a fair amount of "noise" that I have been hopefully successful in shielding you from about this.

That said, I am extremely grateful for your work and testing on these, the information may not be anything actionable against VM, but that was NEVER a goal of mine anyway - knowing that it would never go anywhere with them at all. But your gift of information to the community has been amazing, now each owner just has to decide where they want to go with the information for themselves.

The only credit I will accept for myself is being the public face of the project and a set of semi-skilled hands collecting and forwarding the dead parts for cataloging and evaluations. ALL the credit goes to Jerry and his students.

THANK YOU SO MUCH!!!

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Thu Jan 03, 2019 1:01 am 
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I think you are on the right track. Mass loss, and strength loss (due to grain growth) would both be deleterious to fatigue life. We should have looked at changes in overall length between new and unbroken 150k mile valves. I didn't think of that, but that could be an easy follow up if Geordi still has parts lying around. I think our biggest take away from the whole study was that if you go and buy new valves from an OE type replacement source, you are getting essentially the same thing that was produced in 2006. If someone wanted to chase down getting replacement valves made from a high quality aftermarket valve manufacturer, that could resolve the problems, but is the return on investment worth it? My Jeep is starting to rust on the doors and on the third brake light.
I've had fun with the Jeep, but I don't think I'll be throwing much more money at it. Maybe if it had been a solid front axle, I would keep it going.

WWDiesel wrote:
Thank you Dent for your help in this wonderful report and Geordi for your contributions to this effort.
Does appear from studying the detailed report that loss of some mass in the critical failed area may be a contributing factor which kinda reaffirms my belief that EGR operation with it's soot injection into the combustion process may contribute to possible erosion or exfoliation of the valve stem material over the life of engine.

Other possibility is the valve stem stretching due to cyclic life in the critical exposed area to the hot exhaust exit gases which could cause a decrease in stem mass over time.
Unfortunately the report did not report or compare valve overall length of new versus used exhaust valves.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Thu Jan 03, 2019 1:58 am 
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Dent wrote:
I think you are on the right track. Mass loss, and strength loss (due to grain growth) would both be deleterious to fatigue life. We should have looked at changes in overall length between new and unbroken 150k mile valves. I didn't think of that, but that could be an easy follow up if Geordi still has parts lying around. I think our biggest take away from the whole study was that if you go and buy new valves from an OE type replacement source, you are getting essentially the same thing that was produced in 2006. If someone wanted to chase down getting replacement valves made from a high quality aftermarket valve manufacturer, that could resolve the problems, but is the return on investment worth it?

This is one for the aftermarket parts suppliers. They probably have the contacts & could find out if the valve is a standard size.
Another solution would be to go up in shaft diameter. Again would be useful for someone in the parts supply chain to ask the question if there is a standard size about.
I would hope that there is motivation to do this, though, fixing the problem also takes away the potential for repeat sales of valves.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Thu Jan 03, 2019 9:34 am 
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layback40 wrote:
Dent wrote:
I think you are on the right track. Mass loss, and strength loss (due to grain growth) would both be deleterious to fatigue life. We should have looked at changes in overall length between new and unbroken 150k mile valves. I didn't think of that, but that could be an easy follow up if Geordi still has parts lying around. I think our biggest take away from the whole study was that if you go and buy new valves from an OE type replacement source, you are getting essentially the same thing that was produced in 2006. If someone wanted to chase down getting replacement valves made from a high quality aftermarket valve manufacturer, that could resolve the problems, but is the return on investment worth it?

This is one for the aftermarket parts suppliers. They probably have the contacts & could find out if the valve is a standard size.
Another solution would be to go up in shaft diameter. Again would be useful for someone in the parts supply chain to ask the question if there is a standard size about.
I would hope that there is motivation to do this, though, fixing the problem also takes away the potential for repeat sales of valves.

Running purely on memory here, I believe there was an effort in the past at one point to locate here in the US an aftermarket manufacturer who could supply new exhaust valves for this engine. I believe someone actually contacted Manley Performance, who manufacturers all kinds of engine valves, in regards to building some custom valves but the cost was going to be quite high. I also believe there was some discussion of using valves from the GM 2.8 baby Duramax but the valves were longer than the OE VM 2.8 valves... :banghead:
http://www.manleyperformance.com/dl/custom_valves.pdf

Going to a valve with a slightly larger diameter simply by boring out the valve guide is certainly a great idea, but then you get into valve keeper (locks) issues that must be overcome. :juggle:

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Thu Jan 03, 2019 1:21 pm 
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I don't know about anyone else, but I've been to Manley twice in person.

They are extremely slow in responding, but have said that they can make customs to match our existing valves for about $60 each - three times the price of factory. I am fairly confident that there is something within their catalog that would be close or even a direct match, but they are NO HELP AT ALL in searching the catalog. They only want to make custom. I'm still working on a CRD in my garage right now, and I *may* have a set of valves still laying around. There is a set with unknown mileage in the head I have, those will be getting swapped out before that head is installed. If anyone wants them, they will be available soon enough.

As far as the loss of diameter on the stem, that would fit logically if the temperatures were enough to soften the metal, when combined with the very high spring pressure and the continual pounding of opening and closing. I can see where the valves might slowly stretch over time.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Thu Jan 03, 2019 6:54 pm 
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geordi wrote:
I can see where the valves might slowly stretch over time.

And add the high soot loading and possible abrasive effects to the exposed area of the exhaust valve stem from the EGR system.
The stateside EGR design may be the additional contributing factor as to why owners in other countries are not reporting similar valve failures???

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Fri Jan 04, 2019 1:08 am 
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Try C&C Valves for new customs. Link to contact info below. I had them make two valves for me to match a set of Manley valves for a Honda engine. Manley was no help at all, claimed they did not make the valves. Even after I sent them a photo off the Manley script on the valve stems they denied they made them and would not help out at any cost. C&C made them for about $20 Can. each. That was about 10 years ago though. I had them make an additional set of 8 intakes and 8 exhausts at the time as well. I just had to send them a sample of each valve. I believe they use blanks from Detroit diesels.


https://411.ca/reverse/search?q=(519)%20364-6051

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Fri Jan 04, 2019 1:32 am 
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WWDiesel wrote:
geordi wrote:
I can see where the valves might slowly stretch over time.

And add the high soot loading and possible abrasive effects to the exposed area of the exhaust valve stem from the EGR system.
The stateside EGR design may be the additional contributing factor as to why owners in other countries are not reporting similar valve failures???


I think you will find the EGR design is a world wide thing. We all have the same engine regardless of where it ended up.
The kk 2.8 crd used the updated engine & appears to not have this problem. No one has offered an explanation as to why the problem was overcome.

The high soot load should be more an issue if the soot stuck to the valve & then burned, this would cause high temps in the valve stem.
I am just throwing ideas out to let people add their comments to.

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 Post subject: Re: >>>>> CRD VALVE FAILURE METAL ANALYSIS FINAL REPORT <<<<
PostPosted: Fri Jan 04, 2019 4:02 pm 
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layback40 wrote:
WWDiesel wrote:
geordi wrote:
I can see where the valves might slowly stretch over time.

And add the high soot loading and possible abrasive effects to the exposed area of the exhaust valve stem from the EGR system.
The stateside EGR design may be the additional contributing factor as to why owners in other countries are not reporting similar valve failures???

I think you will find the EGR design is a world wide thing. We all have the same engine regardless of where it ended up.
The kk 2.8 crd used the updated engine & appears to not have this problem. No one has offered an explanation as to why the problem was overcome.
The high soot load should be more an issue if the soot stuck to the valve & then burned, this would cause high temps in the valve stem.
I am just throwing ideas out to let people add their comments to.

I believe it has been posted that the US EGR system on these engines were the only one of its design worldwide???
And no I have not said soot is sticking to the valve, have not even suggested that as a premise as that could be a whole other theory to contemplate but certainly plausible. :banghead:
What as a theory I was throwing out was: that high soot injection rates into the intake flow stream and into the combustion process could cause solid particle erosion or a chemical exfoliation of the valve stem material itself in the exposed area and thus weakening of the valve stem over time which along with adding the long cyclic life loading from the valve spring could ultimately cause stem failure. :idea: :ALONE:

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