Cylinder head wear

akklingler · **Joined:** Thu Oct 13, 2016 3:19 pm **Posts:** 12

At what mileage should the head be pulled to be rebuilt? Has anybody pulled one apart at around 200k miles? How do they look as far as valve seats? Has anybody seen more rocker issues on the exhaust side then on the intake side?

flash7210 · **Posted:** Sat Jan 21, 2017 9:05 pm

At 160,000 miles my valves, guides, and seats were all in great shape.
The cracks, on the other hand, meant the whole head needed to be replaced.

If you really want to remove the head for maintenance, replace the exhaust valves, install new valve guide seals, and lap all the valves.

Otherwise, if you are not leaking coolant into the exhaust, I wouldnt remove the head for anything.

geordi · **Posted:** Sat Jan 21, 2017 9:28 pm

Generally speaking, there is not much to do on these heads. The failures that have been seeing have primarily been on the exhaust side, and between 150 and 200,000 miles. It depends on how much EGR usage has been during the life of the vehicle, but really the major failure point has not been valve seats which are pressed in to the head, but on the valve stems that separate for unknown reasons.

The current thinking at the moment, is to pull the valves and replace them and lap them in. At least if they are the same as stock, they will provide another 150k+ and by that time the vehicle will be close to 300k... and we may know a lot more about the failure mode.

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PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

geordi wrote:

Generally speaking, there is not much to do on these heads. The failures that have been seeing have primarily been on the exhaust side, and between 150 and 200,000 miles. It depends on how much EGR usage has been during the life of the vehicle, but really the major failure point has not been valve seats which are pressed in to the head, but on the valve stems that separate for unknown reasons.

The current thinking at the moment, is to pull the valves and replace them and lap them in. At least if they are the same as stock, they will provide another 150k+ and by that time the vehicle will be close to 300k... and we may know a lot more about the failure mode.

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So how many CRD have dropped a valve ? in your valve research tread it says 3 !! and some of the 3 had work done by you on the head

And also who's current thinking say you need to change the valve at 150k ?

geordi · **Posted:** Sun Jan 22, 2017 12:46 pm

Trying to suggest a correlation without causation again? I have already answered this question but since you like to repeat yourself, here is the answer again:

I am currently aware of 7 valve failures, and the ones that I have worked on have been brought to me AFTER the valve failures. There was one CRD that I did work above the valves (the head was not disturbed) that suffered a failure after I worked on the engine. But that engine was at 200k miles and the owner himself made the determination that nothing I did could have caused the valve failure.

As far as current consensus, that is among the owners that I have spoken with. Obviously far more than that agree with the thought process because IDparts has had to place multiple orders to their Italian suppliers for the valves - they keep selling out, and not only to me.

WWDiesel · **Posted:** Sun Jan 22, 2017 1:14 pm

geordi wrote:

Trying to suggest a correlation without causation again? I have already answered this question but since you like to repeat yourself, here is the answer again:

I am currently aware of 7 valve failures, and the ones that I have worked on have been brought to me AFTER the valve failures. There was one CRD that I did work above the valves (the head was not disturbed) that suffered a failure after I worked on the engine. But that engine was at 200k miles and the owner himself made the determination that nothing I did could have caused the valve failure.

As far as current consensus, that is among the owners that I have spoken with. Obviously far more than that agree with the thought process because IDparts has had to place multiple orders to their Italian suppliers for the valves - they keep selling out, and not only to me.

What ever happened the metallurgical tests that were supposedly being performed on some of the failed valves versus new VM valves?
The results of that type of tests may well indeed help some people on here to make a conscious decision as whether to go ahead and proactively pull a head and replace all exhaust valves.

I also remember some discussion a while back on the possibility of the EGR SOOT eroding some of the valve stems due to either the stratification of the soot in the flow pattern or a chemical reaction with resulting corrosion on the valve stems due to the exhaust soot. So as you stated, EGR operation and / or length of time of being in service may impose a big impact on any decisions as to whether or not to install new valves! Did anything thing ever surface on this theory as well??

I know more information would help greatly in understanding the urgency in how soon it should be performed since mine rolled over 155k yesterday! :roll:

Dent wrote:

I am a professor at the Colorado School of Mines in the Department of Metallurgical and Materials Engineering. If you would like to send me your broken parts, and can supervise a study on the failure mechanism(s). I can't promise anything until I see the parts, but there is a chance we can determine why these valves are failing. PM me and I will give you my address to send the parts. The more the better. I will post results here.

ANYONE have any additional information on any of this or even a good theory, please share!

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

geordi wrote:

Trying to suggest a correlation without causation again? I have already answered this question but since you like to repeat yourself, here is the answer again:

I am currently aware of 7 valve failures, and the ones that I have worked on have been brought to me AFTER the valve failures. There was one CRD that I did work above the valves (the head was not disturbed) that suffered a failure after I worked on the engine. But that engine was at 200k miles and the owner himself made the determination that nothing I did could have caused the valve failure.

As far as current consensus, that is among the owners that I have spoken with. Obviously far more than that agree with the thought process because IDparts has had to place multiple orders to their Italian suppliers for the valves - they keep selling out, and not only to me.

I'm not trying to suggest a correlation without causation, but maybe you are ?? , this forum is aware of 3 valve failure and some are from head that someone as done work on it ! ( you like that better...)

I don't see any concensus here other than you speculating on some valve failure !! Do you remember what you have said about this ?

Geordi said : A disturbing trend is starting to take shape, and I am looking to gather information from anyone that has experienced a valve failure. There is a potential that *every* CRD might have a major design flaw, and be a ticking time bomb. As the miles start to rack up, the risk increases.

Is that a consensus too or the current thinking at the moment ??

geordi · **Posted:** Sun Jan 22, 2017 1:42 pm

Dent has the valves that broke that I had access to, as well as many more examples of aged valves that had not failed. Part of the time delay on getting the test done was waiting until a graduate class was available who could do much more advanced testing. They should be doing the testing as we speak, over the next few weeks of the spring semester.

The advantage is that our patience has enabled much more advanced testing (to a value of tens of thousands if we were to pay for it directly) that hopefully will answer your questions completely.

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WWDiesel · **Posted:** Sun Jan 22, 2017 2:03 pm

geordi wrote:

Dent has the valves that broke that I had access to, as well as many more examples of aged valves that had not failed. Part of the time delay on getting the test done was waiting until a graduate class was available who could do much more advanced testing. They should be doing the testing as we speak, over the next few weeks of the spring semester.

The advantage is that our patience has enabled much more advanced testing (to a value of tens of thousands if we were to pay for it directly) that hopefully will answer your questions completely.

Thanks; it's not just me, there are many on here which I am sure would love to have knowledge of these results!!!! We await with bated breath!!!! :juggle:

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

akklingler wrote:

At what mileage should the head be pulled to be rebuilt? Has anybody pulled one apart at around 200k miles? How do they look as far as valve seats? Has anybody seen more rocker issues on the exhaust side then on the intake side?

If there is no problem with your head , then no reason to pull it off to rebuild based on mileage like a timing belt !

If after diagnosis you have an issue with the head of your Jeep, take it off ( or get a mechanic to do it ) and bring it to a "competent" head shop to get it inspect , fix or rebuild !

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

WWDiesel wrote:

geordi wrote:

Dent has the valves that broke that I had access to, as well as many more examples of aged valves that had not failed. Part of the time delay on getting the test done was waiting until a graduate class was available who could do much more advanced testing. They should be doing the testing as we speak, over the next few weeks of the spring semester.

The advantage is that our patience has enabled much more advanced testing (to a value of tens of thousands if we were to pay for it directly) that hopefully will answer your questions completely.

Thanks; it's not just me, there are many on here which I am sure would love to have knowledge of these results!!!! We await with bated breath!!!! :juggle:

The result of this evaluation will have no statistical validity as the sampling is too small. like a survey in the U.S.A. consulting only 3 persons...... but I can see Geordi jumping to all kinds of wacky conclusions to this test already :SOMBRERO:

I'm still be curious to see the result too as it's an interesting study but with no real scientific value !! :CAMPING:

WWDiesel · **Posted:** Sun Jan 22, 2017 3:39 pm

PZKW108 wrote:

WWDiesel wrote:

geordi wrote:

Dent has the valves that broke that I had access to, as well as many more examples of aged valves that had not failed. Part of the time delay on getting the test done was waiting until a graduate class was available who could do much more advanced testing. They should be doing the testing as we speak, over the next few weeks of the spring semester.

The advantage is that our patience has enabled much more advanced testing (to a value of tens of thousands if we were to pay for it directly) that hopefully will answer your questions completely.

Thanks; it's not just me, there are many on here which I am sure would love to have knowledge of these results!!!! We await with bated breath!!!! :juggle:

The result of this evaluation will have no statistical validity as the sampling is too small. like a survey in the U.S.A. consulting only 3 persons...... but I can see Geordi jumping to all kinds of wacky conclusions to this test already :SOMBRERO:

I'm still be curious to see the result too as it's an interesting study but with no real scientific value !! :CAMPING:

I have to agree with you from a statistical view of point, but is sure would beat NOTHING, which is what we have now as we try and make a conscious decision as whether to proactively replace all the exhaust valves or not! What else do we have to go on??? :banghead:

lacabrera · **Posted:** Sun Jan 22, 2017 4:35 pm

we call it touting for work here in the UK. I think I would have closed up shop and moved on to different forum. On the subject of valve failure I would take a closer look at the possibilities of cam sprocket moving out of time from the shaft.

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

And when I say "no real scientific" value I'm not talking about the metallurgic research on the valve itself.

but just the statistical speculation point of view

rankom · **Posted:** Sun Jan 22, 2017 5:13 pm

this cylinder head is definitely a weird design LOL , new rockers and lifters are better quality from VM made in POLAND , so for time being , valve supplier remains mystery so as their quality.

Cylinder head wear

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