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Have you had a valve failure? Please fill out the form below (hit quote on post 2) if you have!
Yes 20%  20%  [ 19 ]
No 28%  28%  [ 27 ]
Not Yet (But I'm worried) 32%  32%  [ 31 ]
Not Yet (Not worried) 20%  20%  [ 19 ]
Total votes : 96
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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Wed Oct 24, 2018 1:01 am 
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The valve issue seems fairly limited to the R428 sold in domestic jeeps.

I'm pretty sure there are isolated examples in other offshore markets, but this engine has a sterling reputation as used in multiple brands and multiple countries, where, with proper preventive maintenance, they commonly outlast body and frame even in commercial applications.

The 'big 2' differences US VS Offshore markets:

1) The US EPA approved version of NOx emissions that is slapped on as afterthought to all of the engines sold with domestic Jeeps of the day.

2) The average European vehicle owner tends to like to tinker with their vehicle, especially if it's one they are fond of.
The average US vehicle owner might run it through a car wash a couple times a year, and a "Jiffy Lube" or "Oil Can Henry's" once or twice per year. Beyond that, they perhaps check the oil if they are taking an extended trip, drive it till it breaks, haul it to a shop, and gripe about it to everyone who will listen.
I know there are exceptions to this, and I think they help explain the differences between those with chronic problems, and those with no problems. The first is someone buying a second-hand KJ CRD (or third+) and knowing nothing about this engine's peculiarities, find themselves soon broke down for one of a number of reasons, and probably in a very inconvenient place. As compared to someone who bought theirs within a year or two of brand new, and has paid attention to proper maintenance and repair, and has accumulated 200K+ miles and counting, with relatively small cost of ownership, and none of the cylinders doing a sword swallowing act with the valves. Examples of this exist, but are relatively rare in the US market.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Nov 11, 2018 10:29 pm 
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I have been looking much further into this & wanted to share some further information.
The engines that are discussed are all ENR type. This was the first of the R428 . In other parts of the world the newer version of this engine, the ENS is used in other jeeps like the KK & JK. It is even used in cars from other manufacturers.

One big difference with the ENS is the configuration of the timing belt. The ENS has the belt driving only the inlet cam & the exhaust cam is gear driven from the inlet cam. One should be asking why was this change made? As it is an added expense in the engine. On our ENR motors there is no easy adjustment between the cams. So if there is any miss time between the cams, this could result in the exhaust valves being slightly retarded in their operation. This situation could result in an ongoing small interference for the exhaust valves. This added to the likely bedding in that would occur in the first few 1,000 miles/km after changing a timing belt. Has any one ever checked their belt to see if the tensioner is still within adjustment? With the length of the belt between the crank & fuel pump being large enough to allow a harmonic vibration to occur it is likely that a small amount of belt stretch could occur. The belt length between pulleys has been reduced with the ENS with the water pump now being on that side. If there was no problem, why was it changed?

Anyone have any thoughts on this?

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Nov 12, 2018 2:25 pm 
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The changes you reference could be due to many things, but I do not believe that belt stretch is one of them. There should be no harmonic interference anywhere in the belt system as the only driven belt is the crankshaft, and the other pulleys would all stop any vibrations from the long end between the crank and the tensioner or the fuel pump from propagating at all.

I also have verified the timing on many of the engines that I have opened up, and found little to no variance with installing the pins - IF they were installed in the right place to begin with. The clearance from the pistons is also equal to about 3 teeth rotation on the cams, or 1-1.5 teeth on the crankshaft. So there is some safety room that would prevent contact if the timing was not-perfect, but also not-catastrophically-out.

There have been suggestions on the FB group that the valve separation could be due to cracking in the coin of the valve that transitions to the stem. I agree this is a good place to investigate, but with the several dozen valves that I have sent to be tested, no mention of this has been made, so I have to conclude that those cracks aren't connected to the failures.

To date - ALL valve failures I have seen have been in the middle of the alloy section of the head, a clean square break as if it was severed by a laser. This is an area of the stem that is not contacted by anything other than hot air. If it was due to continual contact "piston kissing" the valve, I would expect to see some bending of the stem in the alloy section, as there is nothing to prevent it - none has been seen. Once a failure happens, the remains that drop onto the piston often are beaten to hell, so it is difficult to examine those and see anything useful from the actual failure and not the carnage after. But the stems have all looked clean.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Nov 12, 2018 2:54 pm 
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geordi, did you ever get anything back on the metallurgical tests on the broken valves or did we miss them? :?

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Nov 18, 2018 5:13 pm 
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geordi wrote:
The changes you reference could be due to many things, but I do not believe that belt stretch is one of them. There should be no harmonic interference anywhere in the belt system as the only driven belt is the crankshaft, and the other pulleys would all stop any vibrations from the long end between the crank and the tensioner or the fuel pump from propagating at all.

I also have verified the timing on many of the engines that I have opened up, and found little to no variance with installing the pins - IF they were installed in the right place to begin with. The clearance from the pistons is also equal to about 3 teeth rotation on the cams, or 1-1.5 teeth on the crankshaft. So there is some safety room that would prevent contact if the timing was not-perfect, but also not-catastrophically-out.

There have been suggestions on the FB group that the valve separation could be due to cracking in the coin of the valve that transitions to the stem. I agree this is a good place to investigate, but with the several dozen valves that I have sent to be tested, no mention of this has been made, so I have to conclude that those cracks aren't connected to the failures.

To date - ALL valve failures I have seen have been in the middle of the alloy section of the head, a clean square break as if it was severed by a laser. This is an area of the stem that is not contacted by anything other than hot air. If it was due to continual contact "piston kissing" the valve, I would expect to see some bending of the stem in the alloy section, as there is nothing to prevent it - none has been seen. Once a failure happens, the remains that drop onto the piston often are beaten to hell, so it is difficult to examine those and see anything useful from the actual failure and not the carnage after. But the stems have all looked clean.


I find your comments interesting.
I would suggest that what ever the cause of the failures was fixed going from the ENR to the ENS engine as it would appear the issue was overcome. I am not aware that the valves changed at all. I believe they are still made in the same factory in Turkey.
The only changes that I am aware of are the timing belt/cam drive, the injectors/fuel pump & the location of the water pump. The piston/ring change occurred earlier & I have heard of pre & post failures.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 23, 2018 6:28 pm 
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I am in the process of repairing a CRD for broken rockers. After reading the priceless info here, I ended up pulling the head to send to the machine shop for new exhaust valves just to be safe. This machine shop works on pretty much any kind of internal combustion engine up to and including 1000+ HP cummins engines along with Duramax's & Powerstrokes. The machine shop did the work and afterwards reported the results to me. They ended up having to ream pretty much all the valve guides in the head because they were all tight. Before this the engine had no head gasket or overheating issues. This was all for preventative measures. So, I am wondering if the tight valve guides could be a contributing factor to broken rockers, broken exhaust valves and other CRD maladies?

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Wed Dec 26, 2018 4:03 am 
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kmagg wrote:
I am in the process of repairing a CRD for broken rockers. After reading the priceless info here, I ended up pulling the head to send to the machine shop for new exhaust valves just to be safe. This machine shop works on pretty much any kind of internal combustion engine up to and including 1000+ HP cummins engines along with Duramax's & Powerstrokes. The machine shop did the work and afterwards reported the results to me. They ended up having to ream pretty much all the valve guides in the head because they were all tight. Before this the engine had no head gasket or overheating issues. This was all for preventative measures. So, I am wondering if the tight valve guides could be a contributing factor to broken rockers, broken exhaust valves and other CRD maladies?



kmagg:

I believe the following are all related...

1) ...cylinder head gasket failures.

2) ...cracked cylinder heads.

3) ...broken and bent exhaust valves.

4) ...cracked and broken ceramic glow plugs.

5) ...worn out and broken rocker arms.

In the case of the worn out rocker arms, a contributing factor appears to be the pollutants being pumped back into the engine.

So far, there has been no evidence presented that conclusively proves the exhaust valves themselves are to blame for their failure.

The preponderance of anecdotal evidence points to the cylinder head warping for one reason or another. If you twist up any cylinder head enough, any of the above problems can occur. Your machine shop reporting that your valve guides had to all be reamed is clear evidence of this. It is not normally possible for tolerances to get tighter as an engine wears out in its lifetime, so the only explanation I can come up with is that your cylinder head is warping and twisting.

When a cylinder head warps and twists, valves can become misaligned to the valve seats and the valve stem to valve guide clearance, (already one of the closest tolerances in any internal combustion engine); can get tighter as the cylinder head metal that supports the valve guides begins to bind them up when it warps.

The fact that the exhaust valves appear to be the problem almost 100% of the time in CRD engines lends additional credence to my explanation here. Exhaust valves, the exhaust valve seats, the guides and all of the metal immediately surrounding these parts are the hottest part of the engine during operation, creating the greatest differential in temperatures with the parts and metal next to them. This - in turn - creates the greatest opportunity for parts to start warping and twisting, (and cracking, in some cases).

ENGINES LIKE THE V.M. MOTORI R428 IN THE LIBERTY CRD USE CONSUMER GRADE ARCHITECTURE; THAT IS; ALUMINUM CYLINDER HEAD ON IRON BLOCK CONSTRUCTION. A PROPERLY OPERATING ENGINE COOLING SYSTEM AND MAINTAINING FACTORY DESIGN OF THE COOLANT FLOW ARE ESSENTIAL REMEDIES TO AVOIDING THE ABOVE PROBLEMS.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sat Dec 29, 2018 4:09 pm 
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Your explanation makes sense and supports what I believe are the root causes of these failures. My one question is about the rocker arms. I know disabling the egr is good for the health of the engine. Are there owners who disabled the egr early on in the life of the engine (low miles) and have then proceeded to go another 200,000 miles without rocker arm failure as they seem to do in Europe? The two I have worked on with broken rockers both had approximately 100,000. Neither had overheated or had head gasket problems prior or afterwards. Both had working egr systems and were sooted up in the intake as expected.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sat Dec 29, 2018 8:13 pm 
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kmagg wrote:
Your explanation makes sense and supports what I believe are the root causes of these failures. My one question is about the rocker arms. I know disabling the egr is good for the health of the engine. Are there owners who disabled the egr early on in the life of the engine (low miles) and have then proceeded to go another 200,000 miles without rocker arm failure as they seem to do in Europe? The two I have worked on with broken rockers both had approximately 100,000. Neither had overheated or had head gasket problems prior or afterwards. Both had working egr systems and were sooted up in the intake as expected.



With whom are you agreeing with?


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 30, 2018 9:25 am 
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TURBO-DIESEL-FREAK wrote:
kmagg wrote:
Your explanation makes sense and supports what I believe are the root causes of these failures. My one question is about the rocker arms. I know disabling the egr is good for the health of the engine. Are there owners who disabled the egr early on in the life of the engine (low miles) and have then proceeded to go another 200,000 miles without rocker arm failure as they seem to do in Europe? The two I have worked on with broken rockers both had approximately 100,000. Neither had overheated or had head gasket problems prior or afterwards. Both had working egr systems and were sooted up in the intake as expected.



With whom are you agreeing with?


Sorry. I was agreeing with you TURBO-DIESEL-FREAK

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Weeks Stage 1&2 EGR fixes
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idparts
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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 30, 2018 11:53 am 
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Another factor which Jeff did not mention and I believe may be a big factor in the failure of exhaust valves on this engine is SOOT!
The soot particles dumped into the intake by the EGR valve when exposed to high compression and burning of the fuel could transform into a fine abrasive when leaving the combustion chamber.
This would expose the exhaust valves/stems to a flow of these abrasive particles and the exhaust valves being at a very high temperatures could cause some of the outer metal to exfoliate and weaken the valve stems over time.
Exfoliation can be achieved by mechanical or chemical means.

I believe all exhaust valve failures reported have been the in critical stem to head area so far?
It would be an interesting fact to know if anyone who totally *defeated or removed their EGR system at a very early age in the life of their engine has suffered a valve failure.

(*not just by unplugging the MAF or by installing a tune, but by either mechanically blocking it off or removing the system totally)

:ALONE:

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 30, 2018 11:35 pm 
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WWDiesel wrote:
Another factor which Jeff did not mention and I believe may be a big factor in the failure of exhaust valves on this engine is SOOT!
The soot particles dumped into the intake by the EGR valve when exposed to high compression and burning of the fuel could transform into a fine abrasive when leaving the combustion chamber.
This would expose the exhaust valves/stems to a flow of these abrasive particles and the exhaust valves being at a very high temperatures could cause some of the outer metal to exfoliate and weaken the valve stems over time.
Exfoliation can be achieved by mechanical or chemical means.

I believe all exhaust valve failures reported have been the in critical stem to head area so far?
It would be an interesting fact to know if anyone who totally *defeated or removed their EGR system at a very early age in the life of their engine has suffered a valve failure.

(*not just by unplugging the MAF or by installing a tune, but by either mechanically blocking it off or removing the system totally)

:ALONE:



I believe the soot has been tagged as a culprit for premature rocker arm wear on R428 engines, but it may be a bit of a stretch to think the soot, (even if it were to be chemically changed), will exfoliate the exhaust valves and cause them to break.

I am not dumping on your theory, WWDiesel; I just do not think it is likely. However, I think it bears investigating. Victims of exhaust valve failures should look for evidence of chemical abrasion and/or exfoliation around the broken ends of the valves.

It would indeed be interesting if an original CRD owner realized that the pollution control system on the CRD engine was junk, and removed it early on. What shape would the valves be in, I wonder? Unless, of course, he or she had decided to install an inline thermostat in the upper radiator hose... then head warpage and associate damage that would occur over time is a foregone conclusion.

The two following issues...

1) .... a preponderance of head gasket failures CRD engines seem to have in North America

2) .... the fact that parts get bound up in cylinder heads when they warp

.... are inexorably linked, and therefore leads me to believe that head warpage is the real culprit for exhaust valve failures in CRD engines.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Dec 31, 2018 4:16 am 
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It is a possibility, I suppose, also could be a contributing factor in a more complex series of events.

There is another set of linked events I've also been wondering about, that of failed timing belts and broken valves. It's basically a chicken vs egg scenario, that could equally go either way. A failed valve head dropping into piston-head interference could cause a high mileage timing belt to fail, likewise a failed timing belt will cause equal catastrophe.

If a valve fails on an engine that recently had a timing belt service, there is generally overwhelming evidence as to the order of events.
But when someone has purchased a CRD with no documented history, or is pushing a belt well past it's limit on a high mileage engine, it's almost impossible to tell which was the causal event. I'm beginning to wonder if sometimes we are laying the blame on the timing belt, in error.

Essentially it's all to blame of excess mileage either way, but in here, we've been steadfastly recommending that any CRD whose timing belt is of unknown mileage, change the belt ASAP, and that I still believe is correct to do, but I've been wondering lately if we should also stress the valves as well, seeing how the ones that have actually been tested, failed from excess cycling fatigue.

What say you all?

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Dec 31, 2018 12:46 pm 
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Valves usually break due to age, fatigue1, and a combination of environmental2 conditions to which they are exposed. Exhaust valves are repeatedly loaded and unloaded as they open and close, they can fatigue earlier than normal if the environmental conditions to which they are exposed to are severe enough. These conditions can be a combination of temperature, stress and a corrosive environment. If any of these conditions are excessive, the valve will break its weakest point.

(1) In materials science, fatigue is the weakening of a material caused by repeatedly applied loads. It is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values that cause such damage may be much less than the strength of the material typically quoted as the ultimate tensile stress limit, or the yield stress limit.

(2) Deposits formed on an exhaust valve can be due to the reaction of fuel-borne or airborne contaminants and lubricating oil created during the combustion process as well as the reaction of combustion products with valve materials themselves (chemical). Build-up of deposits on the valve tends to have an insulating effect that can limit critical valve metal cooling (heat transfer) and can make the valve run much hotter than normal which can lead to hot corrosion or exfoliation of the valve stem material.

We know from experience by many on this forum who have suffered timing belt failures just how tough the valves themselves are as many have made severe contact with the top of a piston hitting it hard enough to break or crack rocker arms without sustaining any valve failures in the process. With this history, I believe it rules out valve failure simply caused by contact?

So this leaves failure by some other means or process. Manufacturing defects have been discussed but not entirely ruled out. I think valve stem cracking was ruled out as well in some of the past tests reported? Stated failures are clean breaks between the valve stem and valve mushroom head?
I still believe that the high soot loading these exhaust valves are exposed to from the EGR system may be a contributing factor in their failure, be it chemical as described above or mechanical from abrasives created from the soot and combustion process and possible exfoliation of the valve stem material, or a combination of both.

Bottom line, everything is pure conjecture at this point as we really just don't know for sure what the failure mechanism is unfortunately.
A full metallurgical test on a failed valve may give us some insight....but then again, may not. :banghead:

One thing for sure; if you have to pull your head for any reason, its some mighty cheap insurance to replace the exhaust valves verses suffering a catastrophic engine failure due to a broken exhaust valve. :juggle:

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Dec 31, 2018 7:13 pm 
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WWDiesel wrote:
Valves usually break due to age, fatigue1, and a combination of environmental2 conditions to which they are exposed. Exhaust valves are repeatedly loaded and unloaded as they open and close, they can fatigue earlier than normal if the environmental conditions to which they are exposed to are severe enough. These conditions can be a combination of temperature, stress and a corrosive environment. If any of these conditions are excessive, the valve will break its weakest point.

(1) In materials science, fatigue is the weakening of a material caused by repeatedly applied loads. It is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values that cause such damage may be much less than the strength of the material typically quoted as the ultimate tensile stress limit, or the yield stress limit.

(2) Deposits formed on an exhaust valve can be due to the reaction of fuel-borne or airborne contaminants and lubricating oil created during the combustion process as well as the reaction of combustion products with valve materials themselves (chemical). Build-up of deposits on the valve tends to have an insulating effect that can limit critical valve metal cooling (heat transfer) and can make the valve run much hotter than normal which can lead to hot corrosion or exfoliation of the valve stem material.

We know from experience by many on this forum who have suffered timing belt failures just how tough the valves themselves are as many have made severe contact with the top of a piston hitting it hard enough to break or crack rocker arms without sustaining any valve failures in the process. With this history, I believe it rules out valve failure simply caused by contact?

So this leaves failure by some other means or process. Manufacturing defects have been discussed but not entirely ruled out. I think valve stem cracking was ruled out as well in some of the past tests reported? Stated failures are clean breaks between the valve stem and valve mushroom head?
I still believe that the high soot loading these exhaust valves are exposed to from the EGR system may be a contributing factor in their failure, be it chemical as described above or mechanical from abrasives created from the soot and combustion process and possible exfoliation of the valve stem material, or a combination of both.

Bottom line, everything is pure conjecture at this point as we really just don't know for sure what the failure mechanism is unfortunately.
A full metallurgical test on a failed valve may give us some insight....but then again, may not. :banghead:

One thing for sure; if you have to pull your head for any reason, its some mighty cheap insurance to replace the exhaust valves verses suffering a catastrophic engine failure due to a broken exhaust valve. :juggle:



Yeah; I agree with your most of your assertions. Nothing conclusive has been proven yet, and you are correct in stating that replacing exhaust valves is likely cheap insurance, (how much are they, by the way?).

When I write about cylinder head warpage causing valve failure, I am talking about binding of the valve stem in the valve guide and mis-aligning the valve on the valve seat. In this scenario, I see a valve weakening over time/use, and then breaking... not a valve breaking because of a sudden impact by a piston due to a timing belt failure. This actually lends credence to your assertion that fatigue may be a factor in R428 exhaust valve failure. I disagree with the popular narrative that it is due to the quality of the valves themselves.

The problem with above average exhaust valve failure and cylinder head gasket failures seems to localized in the North American market, so I believe it is the unique situation that we have here that is a major contributor to this phenomenon. By "unique situation", I mean the ridiculous pollution control laws we have here leading to engineers being forced to do stupid things to our engines. This is being made worse by some of the backyard remedies being cooked up by people to get around these pollution control problems.

My primary example for this is the really cheap and terribly short-sighted inline thermostat fix to bring the engine temperatures up to a decent level. There are definitely long term problems with this.

Happy New Year to all of you!


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Dec 31, 2018 10:05 pm 
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TURBO-DIESEL-FREAK wrote:
The problem with above average exhaust valve failure and cylinder head gasket failures seems to localized in the North American market, so I believe it is the unique situation that we have here that is a major contributor to this phenomenon. By "unique situation", I mean the ridiculous pollution control laws we have here leading to engineers being forced to do stupid things to our engines. This is being made worse by some of the backyard remedies being cooked up by people to get around these pollution control problems.

Thanks Jeff, your comment on EGR application only reinforces what I have stated.

Happy New Year to everyone....

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Wed Jan 02, 2019 2:37 pm 
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TURBO-DIESEL-FREAK wrote:

It would indeed be interesting if an original CRD owner realized that the pollution control system on the CRD engine was junk, and removed it early on. What shape would the valves be in, I wonder? Unless, of course, he or she had decided to install an inline thermostat in the upper radiator hose... then head warpage and associate damage that would occur over time is a foregone conclusion.


I can answer this. I purchased mine 2/2005, performed the SEGR mod the earliest the boards were available and had less than 6k on the motor at that time. It ran that way until I GDE'd it in 2016. I had gone through three thermostats before I replaced it w/ HDS, again in 2016. Timing belt and water pump were done at the same time. The motor never had any sort of overheating issue - in fact, w/ the failed thermostats, it was far more often that it was running too cold than too hot.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Wed Jan 02, 2019 5:19 pm 
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Ouch - both exhaust valves... And it is hard to tell in this condition, but it almost looks that both of them failed at the same time, the break in the stem is so clean on both. How many miles?


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Wed Jan 02, 2019 5:19 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: Valve failure research thread - We need your data!
PostPosted: Thu Jan 03, 2019 11:45 am 
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geordi wrote:
Ouch - both exhaust valves... And it is hard to tell in this condition, but it almost looks that both of them failed at the same time, the break in the stem is so clean on both. How many miles?


Not even 70k.

One valve broke clean off - then bounced around, bent, then broke the 2nd valve, then split the piston and wedged it in the sleeve. Motor is locked up - waiting time for me to get back to it. Meanwhile, my 230k Odyssey keeps on clickin' along - though on it's 3rd transmission. ;)

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