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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 22%  22%  [ 14 ]
No 29%  29%  [ 19 ]
Not Yet (But I'm worried) 34%  34%  [ 22 ]
Not Yet (Not worried) 15%  15%  [ 10 ]
Total votes : 65
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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sat Dec 24, 2016 10:06 pm 
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I have never claimed to be any kind of vehicle technician. I am not specially trained in theory of engine design, and I think you will find very few technicians are trained in WHY something is done because that is not germane to their job. Diagnostics and repair are.

I think Flash has the right answer: These are not designed to rotate. The cleaning of the seats is obviously not that important on modern engines. As far as binding in the guides, that is a huge potential issue but I have not seen any evidence thus far for that - all the failures have been below the valve guides entirely. Not a bad guess - and if they weren't oiled, I can see the valve guide wear being a huge issue, but I don't think it is the case on this engine.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sat Dec 24, 2016 11:06 pm 
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well i thing we all work to find right answer , yes some disagree (valve nor rotating ) and others are saying they do rotate in there seats because to prevent misalignment with valve seat and for beater cooling and sealing , and they do rotate but when stop for whatever reason , i say they not making even contact with there seat , that can cause them to overheat and fail .


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 25, 2016 6:24 am 
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geordi wrote:
I have never claimed to be any kind of vehicle technician. I am not specially trained in theory of engine design, and I think you will find very few technicians are trained in WHY something is done because that is not germane to their job. Diagnostics and repair are.

I think Flash has the right answer: These are not designed to rotate. The cleaning of the seats is obviously not that important on modern engines. As far as binding in the guides, that is a huge potential issue but I have not seen any evidence thus far for that - all the failures have been below the valve guides entirely. Not a bad guess - and if they weren't oiled, I can see the valve guide wear being a huge issue, but I don't think it is the case on this engine.



Sorry geordi, but knowledge of the fundamentals of engine design and why things are designed in a particular way they are an important part of a real technician's training. It is also an important part of a technician's ability to diagnose a problem. Otherwise you end up with people who think they know better how to repair and upgrade an engine's operation than the actual people who designed the engine, such as yourself.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 25, 2016 8:31 am 
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TURBO-DIESEL-FREAK wrote:
geordi wrote:
I have never claimed to be any kind of vehicle technician. I am not specially trained in theory of engine design, and I think you will find very few technicians are trained in WHY something is done because that is not germane to their job. Diagnostics and repair are.

I think Flash has the right answer: These are not designed to rotate. The cleaning of the seats is obviously not that important on modern engines. As far as binding in the guides, that is a huge potential issue but I have not seen any evidence thus far for that - all the failures have been below the valve guides entirely. Not a bad guess - and if they weren't oiled, I can see the valve guide wear being a huge issue, but I don't think it is the case on this engine.



Sorry geordi, but knowledge of the fundamentals of engine design and why things are designed in a particular way they are an important part of a real technician's training. It is also an important part of a technician's ability to diagnose a problem. Otherwise you end up with people who think they know better how to repair and upgrade an engine's operation than the actual people who designed the engine, such as yourself.

A little bit quick to judge dont you think?

Very few automotive and diesel technicians and machinists know all the intricacies of the valve train.
A degree in mechanical engineering is not a requirement for being a technician.
And given the various designs Ive seen over the years, its obvious that the engineers never had to turn a wrench for a living.

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intake elbow and EGR delete. 5 volt bosch glow plugs
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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 25, 2016 8:35 am 
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Image
These are the exhaust valves, cyl 4, on my old cracked head.

Notice that the wear pattern is directly over the center of the tip.
It obvious these valves were not rotating.

Without rotators, valves can still rotate but not in a predictable manner.
In this case two criteria must be met.
1. There must be enough friction for the rocker tip to push against the valve stem tip.
2. The rocker must be machined in such a way that it presses more on the side of the valve stem tip. Pushing directly over center will not make it rotate.

_________________
Bought my '05 CRD on June 2nd '07, used with 29,000 miles.
intake elbow and EGR delete. 5 volt bosch glow plugs
Yeti stage 2 ECU tune. Straight pipe exhaust. DIY intercooler hoses
Provent and modified factory 180F thermostat
Replaced cylinder head (cracked) at 160,000 miles + ARP studs
2.5 inch lift, JBA upper arms, 235-85-16 tires.
Still love it.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 25, 2016 10:56 am 
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VALVE ROTATION PLAY IN VALVE /SEAT INSERT …. okay i see there is some agreement ,,, rotation is important and helps grinding away deposits which prevents HOT SPOTS , forming and help maintaining good sealing and TERMAL CONTACT of the valve to seat . i remember reading this in some older books , bare in mind this may not apply to this engine LOL


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 25, 2016 6:04 pm 
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fare question for you guys that believe that valve stem does not rotate , why it does not and why is not so important on this engine design .


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sun Dec 25, 2016 6:42 pm 
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flash7210 wrote:
TURBO-DIESEL-FREAK wrote:
geordi wrote:
I have never claimed to be any kind of vehicle technician. I am not specially trained in theory of engine design, and I think you will find very few technicians are trained in WHY something is done because that is not germane to their job. Diagnostics and repair are.

I think Flash has the right answer: These are not designed to rotate. The cleaning of the seats is obviously not that important on modern engines. As far as binding in the guides, that is a huge potential issue but I have not seen any evidence thus far for that - all the failures have been below the valve guides entirely. Not a bad guess - and if they weren't oiled, I can see the valve guide wear being a huge issue, but I don't think it is the case on this engine.



Sorry geordi, but knowledge of the fundamentals of engine design and why things are designed in a particular way they are an important part of a real technician's training. It is also an important part of a technician's ability to diagnose a problem. Otherwise you end up with people who think they know better how to repair and upgrade an engine's operation than the actual people who designed the engine, such as yourself.

A little bit quick to judge dont you think?

Very few automotive and diesel technicians and machinists know all the intricacies of the valve train.
A degree in mechanical engineering is not a requirement for being a technician.
And given the various designs Ive seen over the years, its obvious that the engineers never had to turn a wrench for a living.



Actually, NO, I am not being too quick to judge here. I never said a technician requires the same level of training that an engineer has, but that he or she should at least have training in the fundamentals of automotive design. It is not necessary to know EVERYTHING about a valve train, but some education is necessary. I do not know what the level of training is required in the U.S., but I was taught the fundamentals in high school automotives courses.

geordi was asking why valves rotate. This is most certainly not a question that requires a mechanical engineer to answer, and I learned why they rotate back in high school in the early 1980s.

As for dumping on automotive engineers, you are wrong here as well. It is almost always the case where flaws in automotive design are directly the cause of the bean counters the manufacturers employ to maximize profits, or designs are altered from what is best to what suits the government bureaucrats by political fiat, (EPA regulations, safety regulations and such).

With geordi, you have someone who has the skill to repair a blown CRD engine cylinder head, but not the background knowledge to know why things are happening. His general inquiry asking about why valves rotate is proof of that. In fact, this entire thread is going in the wrong direction because geordi refuses to consider the undisputed fact that the number 1 cause of cylinder head failures and related problems in internal combustion engines are cooling system failures, and instead focuses on a somewhat dubious notion that the torque-to-yield bolts are at fault here. Re-visit the first page of this thread to see for yourself; he blew me off rudely when I suggested he include driving habits, cooling system issues and modifications. This is now not surprising to me, as he has posted more than once that he does not believe that blocking off the cooling system bypass circuit is a big deal, and that he has a "theory" that other cooling system circuits will take over the task of circulating the engine coolant adequately during warm-up.

So, despite the fact that geordi has made no claims to being a technician of any kind, he has "theories" about how the R428 should operate. He believes - essentially - that he knows more than the engineers who designed this engine. This shows a rather blatant display of ignorance AND arrogance, all at the same time.

Cylinder head gasket failures and valve failures seem to be an affliction of the North American CRD engine, yet problems are much less prevalent in CRD engines in other markets around the world. Someone has to ask why, and investigate for themselves. Has anyone even bothered to ask V.M. Motori if the R428 engine is produced in more than one manufacturing facility, and if they have had problems with their valves in other markets? Somehow I doubt this.

I do not believe this thread will ever go anywhere until those members here who are interested in getting some results consider ALL of the possibilities of why there is a prevalence of cylinder head gasket issues and valve failures in North American R428 engines.


Last edited by TURBO-DIESEL-FREAK on Fri Jan 13, 2017 3:37 am, edited 1 time in total.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Dec 26, 2016 6:46 pm 
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I haven't the time to type the full version but the valve would rotate because the stem is not in contact with the rocker 100% of the time, even with hydraulic valve clearance valve adjusters. At higher RPM all engines do experience some valve bounce, its something that we worked on to prevent excessively for obverse reasons years ago. Maybe its possible due to the low RPM range here, there is no rotation?

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Mon Dec 26, 2016 7:04 pm 
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lacabrera wrote:
I haven't the time to type the full version but the valve would rotate because the stem is not in contact with the rocker 100% of the time, even with hydraulic valve clearance valve adjusters. At higher RPM all engines do experience some valve bounce, its something that we worked on to prevent excessively for obverse reasons years ago. Maybe its possible due to the low RPM range here, there is no rotation?

Valve bounce = valve float = BAD
This would cause the rocker to hammer the tip of the stem, mushrooming it.
Sometimes, on old cam-in-block engines, the lifter would also bounce off the cam lobe.
The solution for high rpm race engines is to use stiffer valve springs. And in some cases, retension springs on the lifters.

I agree that with the low rpm of a diesel engine, there is no valve rotation.

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Bought my '05 CRD on June 2nd '07, used with 29,000 miles.
intake elbow and EGR delete. 5 volt bosch glow plugs
Yeti stage 2 ECU tune. Straight pipe exhaust. DIY intercooler hoses
Provent and modified factory 180F thermostat
Replaced cylinder head (cracked) at 160,000 miles + ARP studs
2.5 inch lift, JBA upper arms, 235-85-16 tires.
Still love it.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Tue Dec 27, 2016 10:25 am 
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flash7210 wrote:
lacabrera wrote:
I haven't the time to type the full version but the valve would rotate because the stem is not in contact with the rocker 100% of the time, even with hydraulic valve clearance valve adjusters. At higher RPM all engines do experience some valve bounce, its something that we worked on to prevent excessively for obverse reasons years ago. Maybe its possible due to the low RPM range here, there is no rotation?

Valve bounce = valve float = BAD
This would cause the rocker to hammer the tip of the stem, mushrooming it.
Sometimes, on old cam-in-block engines, the lifter would also bounce off the cam lobe.
The solution for high rpm race engines is to use stiffer valve springs. And in some cases, retension springs on the lifters.

I agree that with the low rpm of a diesel engine, there is no valve rotation.


I agree valve bounce is bad but the rocker is not in contact with the stem 100% of the time if it was the valve head would not seat correctly when closed. Even with hydraulic lifters, they design them to give a small tolerance to allow for this, because the oil pressure extending the lifter would prevent the valve from closing completely. On older engines especially push rod engines the gap between rocker and valve can be considerable to allow for expansion. So the hammering affect mentioned is normal especially on a cold engine.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Thu Dec 29, 2016 11:14 am 
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It is my understanding that valves rotate due to the spiral wind of the spring and the slight clearance allowed by the lash adjuster as the valve closes?

I have the thermostat in the top hose and know for a fact that it has no effect on cold engine coolant by-pass, all that thermostat does is block coolant flow to the rad when cold to promote faster warmup. The bypass system is built into the thermostat housing itself and uses a hose from the housing down to the water pump. The hose flows coolant to the water pump and the pump pushes that coolant through the engine and head to keep the temps even as possible whether the engine is warm or not.

Sorry I don't have all my history and stuff entered I never figured out how to do it. I have an 05 liberty with 140K mi ARP ID parts tubo new Rocker arms timing belt ect.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Thu Dec 29, 2016 11:46 am 
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Interesting vid look how the valves start to rotate as the RPM increases.
https://www.youtube.com/watch?v=vcyT18qk8ls
Not our head but has the same plat form.

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Thu Dec 29, 2016 12:17 pm 
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x-tech wrote:
It is my understanding that valves rotate due to the spiral wind of the spring and the slight clearance allowed by the lash adjuster as the valve closes?
regardless of the mechanisms that allow for valve rotation, my pictures above show that the valves are not rotating

I have the thermostat in the top hose and know for a fact that it has no effect on cold engine coolant by-pass, all that thermostat does is block coolant flow to the rad when cold to promote faster warmup. The bypass system is built into the thermostat housing itself and uses a hose from the housing down to the water pump. The hose flows coolant to the water pump and the pump pushes that coolant through the engine and head to keep the temps even as possible whether the engine is warm or not.
The factory thermostat is like Schrodinger's cat. Its sealed up inside a box and we dont really know whats happening inside.
The way its supposed to function is that when cold, the main outlet is closed and the bypass outlet is open. When coolant temp gets to about 176F, the main outlet opens and the bypass closes.
So, if you put in a 195F in-line thermostat, at 176F the main outlet opens but coolant flow now butts up against a closed 195F in-line and at the same time the bypass closes. In this case, from about 176F to 195F there is absolutely zero coolant flow through the thermostat housing.
Of course this assumes a fully functioning factory thermostat.
But what if the factory thermostat has failed in some way? Either being stuck open in some position or opening too early? Its difficult to know exactly whats going on under those conditions.
Now you could argue that there are other paths for coolant to bypass the thermostat. This is true. Like through the heater core, or EGR cooler, or the small hose going up to the coolant tank. But do these paths offer sufficient flow when both the bypass and main outlets are closed? I dont know.

Sorry I don't have all my history and stuff entered I never figured out how to do it. I have an 05 liberty with 140K mi ARP ID parts tubo new Rocker arms timing belt ect.

Bottom line.
Nobody knows for sure what is causing valves to break and heads to crack.
I'm going to assume that its related to heat in the cylinder head and coolant flow.
Therefore I err on the side of caution and ensure that all flow paths out of the head are free from obstruction and that the thermostat ports open and close when needed.

_________________
Bought my '05 CRD on June 2nd '07, used with 29,000 miles.
intake elbow and EGR delete. 5 volt bosch glow plugs
Yeti stage 2 ECU tune. Straight pipe exhaust. DIY intercooler hoses
Provent and modified factory 180F thermostat
Replaced cylinder head (cracked) at 160,000 miles + ARP studs
2.5 inch lift, JBA upper arms, 235-85-16 tires.
Still love it.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Thu Dec 29, 2016 12:41 pm 
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The theory of the EGR dumping soot laden air against the stems of the intake valves and the abrasive and corrosive effects on the valve stems seems to be one of the most plausible theories I have read... seems to be the worst on number three valves according to what was posted...
Of course this does not explain why the exhaust valves break...

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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Thu Dec 29, 2016 3:42 pm 
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The picture of the valve tip can (I think) be misleading, the valve can turn and still contact the center provided the rocker arm is ground slightly convex to allow for better oil access and reduced friction.

I see what you mean IF the CRD is designed to shut off the by pass when the stat fully open then I would think problems should be evident on the temp gauge as the sending unit is mounted into the head. My in-line stat has been installed 50K mi with no trouble(I can't believe just typed that). I understand that some one modifies the stock thermostat to a conventional type. IF a normal stat is used in the modified housing then the by-pass is not blocked when hot.

I have the GDE eco hot tune and worry about the possibly of much higher combustion temps. On a gas engine the increased efficiency and temp is countered by adding fuel to compensate for the more burnable air. On a diesel I don't know how its done. If the combustion temps are increased then valve damage could result.

On the engine that that dropped a valve at 200mi after head work was done I would suspect a valve guide to seat misalignment, the misalignment flexes the valve and bang.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Thu Dec 29, 2016 7:34 pm 
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x-tech wrote:
The picture of the valve tip can (I think) be misleading, the valve can turn and still contact the center provided the rocker arm is ground slightly convex to allow for better oil access and reduced friction.
if the valves were rotating, the wear pattern would be circular not rectangular

I see what you mean IF the CRD is designed to shut off the by pass when the stat fully open then I would think problems should be evident on the temp gauge as the sending unit is mounted into the head. My in-line stat has been installed 50K mi with no trouble(I can't believe just typed that). I understand that some one modifies the stock thermostat to a conventional type. IF a normal stat is used in the modified housing then the by-pass is not blocked when hot.
unless you changed something, the temp sending unit is in the thermostat housing

I have the GDE eco hot tune and worry about the possibly of much higher combustion temps. On a gas engine the increased efficiency and temp is countered by adding fuel to compensate for the more burnable air. On a diesel I don't know how its done. If the combustion temps are increased then valve damage could result.
on a diesel engine, its not combustion temp to worry about, its exhaust gas temp (EGT). More fuel = higher EGT. More boost = lower EGT. Finding the right balance is key to diesel engine tuning. Given the nature of the "eco" tune, I dont think GDE is adding enough more fuel for EGT to be a problem.


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Bought my '05 CRD on June 2nd '07, used with 29,000 miles.
intake elbow and EGR delete. 5 volt bosch glow plugs
Yeti stage 2 ECU tune. Straight pipe exhaust. DIY intercooler hoses
Provent and modified factory 180F thermostat
Replaced cylinder head (cracked) at 160,000 miles + ARP studs
2.5 inch lift, JBA upper arms, 235-85-16 tires.
Still love it.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sat Jan 07, 2017 4:09 pm 
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So we have 3 valve failures out of this whole forum !!

most of em with really high millage and most of em are from vehicule geordi have work on the engine......

Yes I agree we have some kind of alarming trend going on here !


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sat Jan 07, 2017 4:36 pm 
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x-tech wrote:
On the engine that that dropped a valve at 200mi after head work was done I would suspect a valve guide to seat misalignment, the misalignment flexes the valve and bang.


This would be plausible and might play into the accusation that PZKW108 seems to be trying to make, except for a couple glaring facts:

I did not remove the head or do anything with the valves on the engine that failed shortly after I worked on it. I replaced the bolts with studs - one by one without disturbing the head gasket - and put in new rockers. Elbow kit, glow plugs, and timing belt kit was the rest of the work. Tell me how anything of that could have caused a valve stem to snap? I certainly can't come up with any way.

All the other failures that I have come in contact with have been on CRDs that broke before I ever came near them. I was called in after the fact.

As for the numbers, I personally have seen 6 engines with valve failures, and only the one mentioned above had I done any work on prior to the failure. I cannot speak to the history of the others because I do not know how they were treated. If there is a suggestion you want to make PZKW, come right out and say it. But you might want to also mention that you have never seen my work on your own CRD, so you are basing your opinion on thin evidence indeed.


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 Post subject: Re: Valve failure research thread - We need your data!
PostPosted: Sat Jan 07, 2017 5:16 pm 
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geordi wrote:
x-tech wrote:
On the engine that that dropped a valve at 200mi after head work was done I would suspect a valve guide to seat misalignment, the misalignment flexes the valve and bang.


This would be plausible and might play into the accusation that PZKW108 seems to be trying to make, except for a couple glaring facts:

I did not remove the head or do anything with the valves on the engine that failed shortly after I worked on it. I replaced the bolts with studs - one by one without disturbing the head gasket - and put in new rockers. Elbow kit, glow plugs, and timing belt kit was the rest of the work. Tell me how anything of that could have caused a valve stem to snap? I certainly can't come up with any way.

All the other failures that I have come in contact with have been on CRDs that broke before I ever came near them. I was called in after the fact.

As for the numbers, I personally have seen 6 engines with valve failures, and only the one mentioned above had I done any work on prior to the failure. I cannot speak to the history of the others because I do not know how they were treated. If there is a suggestion you want to make PZKW, come right out and say it. But you might want to also mention that you have never seen my work on your own CRD, so you are basing your opinion on thin evidence indeed.


You could easily have push or dropped something on a valve and loosen the lock and didn't even realise it.
you never been trained as a tech you might be missing something ! :juggle:

You have never work on my CRD but I've been reading your pretentious posts for years.

You pretend to be the best CRD tech in the U.S. but your not a tech by trade ??? you have no money to resolve any problem you could have cause on a vehicule !!!

You are starting fear mongering post like the "CRD Head Bolt Research Request: We need your data!" and this one for getting member here to do more work than they actually need to get done for your benefit.

You are exaggerating the fact that on any car forum we see a lot of posts about failure because peoples post to find a solution to there problems more than anything else.
The CRD engine is high maintenance but not a bad engine or prone to fail

As per the proof you are asking from me...... :ROTFL:

I think your the one that should have proof of all the wacky theories your coming up with !

Your are the one who should prove of your credential as a tech to have the vendor title

And I don't think anyway a private individual should be a forum vendor, especially an individual with no CREDIT and/or NOT an accredited technician !!!!!



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