Originally Posted by Vette @ 71

Based upon your personal experience what do you contribute/causing the valve problem. Do you subscribe to the concentricity theory valve to guide as Katech is stating.

Originally Posted by Michael_D

You have my attention. Analyzing vibration data makes my head feel like it’s about to explode. The smartest man (or woman) I’ve ever had the pleasure of working with is my employer’s rotating machinery engineer. He continues to amaze me with his diagnosis of a problem by doing nothing more than analyzing vibration data that we send him (we do not have remote monitoring, yet). We had a 15 MW TG go bonkers after a bearing change. We could not get it through the critical stage without tripping from high vibration. Operations immediately came to the conclusion that either the installation was incorrect, or that there was a larger problem with the machine that would require a complete tear down. I sent this engineer the data to review. An hour later he asked for pictures of both bearings – old and new. He thought, through data analysis, that there might be something different with the bearings, even though they had the same part number from the manufacture. Sure enough, the manufacture made a very subtle change, thinking the change would be an improvement, but it instead induced oil whirl. I went back to the manufacture, told them our findings and got a ‘retro’ bearing sent to us. Swapped it out and all was golden. The manufacture changed this bearing’s design back to original for this machine that is still in operation, world-wide. He constantly does things like that.

I think it’s just human nature to jump to conclusions without taking a few steps back, breath for a minute and separate the fluff from the meat of the issue. In my professional world, we cannot simply change a part because it failed. We must find out why it failed. Down time costs result in lost revenue of roughly $500 per second. When there is a failure, we analyze the data, and find out why it failed. Call backs to address a repeat failure usually gets unwanted attention from people in the company I would rather not know who I am….

Originally Posted by hoefi

For the record I am a regiestered professional engineer. My engine dropped an exhaust valve back in September 2009. I stripped my own engine down and did my own investigation when GM denied my warrantee. I am the first person on this forum officially reported abnormal guide wear measurements back in January 2010. I provided meaurements, X-Ray, NDT test results to GM even before z0sickTanner started jumping up and down here telling everyone there is an issue with this engine. Do I have data??? Yes, I have data on ONE failed engine. Now, my question to you is, have you examined ANY failed LS7 engine yourself? If not, you have ZERO data compare to my data.

I was at a seminar many many years ago. The lecturer is a geneticist. He made the comment that when he is standing there in front of the large crowd, all he sees is mutants in front of him. I have read your previous posts, and your take on this valve issue is always a vibration one. I guess it's similar to the geneticist seeing only mutants in the crowd. The important question is that have you examine a failed engine as a first step in investigating the problem. Katech has the same issue. Three years ago, they said there is absolutely no issue with the LS7 engine because they have not seen any issue. Twenty months later, they changed their tone and said there is abnormal wear in the valve guides because they are starting to see it. But their comment then was that they have not seen any dropped valve even with the valve guide wear, so there is no danger of dropping valves. In additon, they also said the issue is only contained to a small segment of the population (because that's what GM told them and Katech took that at face value). Now, the last few days, Katech is saying that they are seeing valve guide wear in other model years and confirmed valve heads will fall off with excessive guide wear. All because they are now seeing them. Great, so if you haven't seen something, that something does not exist. Data is great, when it is YOUR data. Someone else's data or observation is not relevant I guess, especially when one considers himself an expert.

Three years after the official start of this valve drop debate and we still have people here convinced that it is less than 1%. I am just shaking my head in disbelief.

I don't post much these days any more. I let Quick do the posting since he is much more effeicent in doing it. My Z has put on about 10,000 miles since the new replacement engine. New heads from WCCH will be going on once they arrive. Should be ready for the road again very soon.

Originally Posted by hoefi

For the record I am a regiestered professional engineer. My engine dropped an exhaust valve back in September 2009. I stripped my own engine down and did my own investigation when GM denied my warrantee. I am the first person on this forum officially reported abnormal guide wear measurements back in January 2010. I provided meaurements, X-Ray, NDT test results to GM even before z0sickTanner started jumping up and down here telling everyone there is an issue with this engine. Do I have data??? Yes, I have data on ONE failed engine. Now, my question to you is, have you examined ANY failed LS7 engine yourself? If not, you have ZERO data compare to my data.

I was at a seminar many many years ago. The lecturer is a geneticist. He made the comment that when he is standing there in front of the large crowd, all he sees is mutants in front of him. I have read your previous posts, and your take on this valve issue is always a vibration one. I guess it's similar to the geneticist seeing only mutants in the crowd. The important question is that have you examine a failed engine as a first step in investigating the problem. Katech has the same issue. Three years ago, they said there is absolutely no issue with the LS7 engine because they have not seen any issue. Twenty months later, they changed their tone and said there is abnormal wear in the valve guides because they are starting to see it. But their comment then was that they have not seen any dropped valve even with the valve guide wear, so there is no danger of dropping valves. In additon, they also said the issue is only contained to a small segment of the population (because that's what GM told them and Katech took that at face value). Now, the last few days, Katech is saying that they are seeing valve guide wear in other model years and confirmed valve heads will fall off with excessive guide wear. All because they are now seeing them. Great, so if you haven't seen something, that something does not exist. Data is great, when it is YOUR data. Someone else's data or observation is not relevant I guess, especially when one considers himself an expert.

Three years after the official start of this valve drop debate and we still have people here convinced that it is less than 1%. I am just shaking my head in disbelief.

I don't post much these days any more. I let Quick do the posting since he is much more effeicent in doing it. My Z has put on about 10,000 miles since the new replacement engine. New heads from WCCH will be going on once they arrive. Should be ready for the road again very soon.

Originally Posted by JWingo

I apologize for the time delay! Had to cut grass. Wife cracked the whip on me. I never meant to imply "there never was an issue within the heads" of the LS7. Absolutely was as GM admitted to and unfortunately some have had the experience of. All my comments were viewed from a root cause analysis point of view. Before any conclusion can be made, data has to be considered. It may be one of many variables. It may be a combination. Nothing wrong with many of the repairs I see people doing. Better than failing. However, assuming all people are going to fail is very premature. Sorry to hear of your failure but that does not mean everyone will fail as your 2009 did. Which is named as a year that had a potential issue by GM. I thank you for your opinion. As far as what I have for data. I have not failed an LS7. So I have 2. I had a 2008 with 30k miles and then bought the 2013. Does that indicate there will be no future failures? No. It's inconclusive. Total number on the roads today versus the number of failures are what I have referred to. Calculated uptime. Expert? Sir, I want even dignify that with comment.

Originally Posted by Vette @ 71

As they (GM ) has gone on record by stating it is a "machining error", their solution was to correct the error, as they believed they had and move on with producing more engines.

Unfortunately for them it appears the problem (machining problem) is far more widespread than they believed or had hoped for and which naturally casts doubt on their integrity as it relates to having identified the source of the problem and put in place proper corrective actions to eliminate the problem..

Originally Posted by '06 Quicksilver Z06

And just how do you know what they "believed" or "hoped for"?

The only thing that you can say, is:

"Unfortunately for them it appears the problem (machining problem) is far more widespread than they STATED."

And with regard to your #5 above in a prior post, well I got a real kick out of that.

If he knows so much more than I do about this matter, then how come his car isn't fixed, but mine is as solid as a rock?

My signature is below, and as far as reliability or anything else you would like to name, I will put my car against his, which currently has a KNOWN worn out exhaust guide in it as of two months ago, which he has yet to state that he has addressed, or more importantly, leave him out of it, I'll put it up against YOURS for that matter, in terms of reliability or anything else, any day.



'06 Quicksilver Z06:

2006 C6 Z06

DRM Bilstein shocks
2008 axle shafts
MGW shifter
Katech LS9X clutch
Tick remote clutch bleeder
Callaway Honker CAI
Ported stock Formato Throttle body
Ported stock Formato intake manifold
Katech Torquer 110 Cam
Katech C5R Timing Chain
WCCH Stage 2 Cylinder Heads, Stainless steel exhaust valves
C.H.E. Rockers
KOOKS 1 7/8 headers X Pipe with Cats
NGK TR6 Spark plugs
Elite Catch Can
Tuning by Ed Hutchings


I understand that he is your hero. But when it comes to this matter, I feel very comfortable with what I've done in my own car thus far.

Originally Posted by Vette @ 71

Congratulations on what you believe you have accomplished with your car I hope it lasts a millennia of reliability.

However, as is your ridiculous debating style, the discussion is not and never has been your car vs his car or your car vs my car.

You seem to have difficulty staying focused and on track.

Originally Posted by Vette @ 71

Do you really believe that by "fixing your car" as you hope and I also hope for, provides you with superior knowledge? Really? Give careful consideration to what you said..

The status of his car or anyone's car has no relevance. The objective is to understand what is going on with the valves/guides.

Originally Posted by Vette @ 71

We are not comparing whose car is more reliable..

Do you proof read and perform a sanity check before you push the send key?

Originally Posted by hoefi

For the record I am a regiestered professional engineer. My engine dropped an exhaust valve back in September 2009. I stripped my own engine down and did my own investigation when GM denied my warrantee. I am the first person on this forum officially reported abnormal guide wear measurements back in January 2010. I provided meaurements, X-Ray, NDT test results to GM even before z0sickTanner started jumping up and down here telling everyone there is an issue with this engine. Do I have data??? Yes, I have data on ONE failed engine. Now, my question to you is, have you examined ANY failed LS7 engine yourself? If not, you have ZERO data compare to my data.

I was at a seminar many many years ago. The lecturer is a geneticist. He made the comment that when he is standing there in front of the large crowd, all he sees is mutants in front of him. I have read your previous posts, and your take on this valve issue is always a vibration one. I guess it's similar to the geneticist seeing only mutants in the crowd. The important question is that have you examine a failed engine as a first step in investigating the problem. Katech has the same issue. Three years ago, they said there is absolutely no issue with the LS7 engine because they have not seen any issue. Twenty months later, they changed their tone and said there is abnormal wear in the valve guides because they are starting to see it. But their comment then was that they have not seen any dropped valve even with the valve guide wear, so there is no danger of dropping valves. In additon, they also said the issue is only contained to a small segment of the population (because that's what GM told them and Katech took that at face value). Now, the last few days, Katech is saying that they are seeing valve guide wear in other model years and confirmed valve heads will fall off with excessive guide wear. All because they are now seeing them. Great, so if you haven't seen something, that something does not exist. Data is great, when it is YOUR data. Someone else's data or observation is not relevant I guess, especially when one considers himself an expert.

Three years after the official start of this valve drop debate and we still have people here convinced that it is less than 1%. I am just shaking my head in disbelief.

I don't post much these days any more. I let Quick do the posting since he is much more effeicent in doing it. My Z has put on about 10,000 miles since the new replacement engine. New heads from WCCH will be going on once they arrive. Should be ready for the road again very soon.

Originally Posted by '06 Quicksilver Z06

Guides are still wearing out prematurely in these engines. Even those in late production.

Ask Howie above about his 2011 built engine and I have pointed go one in here which was a September 2012 build which Mark 200X tried to dismiss because it was an intake guide. [...]

Originally Posted by Mark200X

I dismissed it because it was not proof of your claim that the OEM exhaust valve is culprit.

In fact it is circumstantial evidence that machining or geometry is the culprit, which you vehemently deny.

So in trying to misrepresent what I said/my position, you only condemn your own position to failure. Priceless

Originally Posted by z0sicktanner

How many will it take for ppl to see they are wearing guides and it's causing failures even Katech has said this so what is the debate at this point? look at how many ppl on this forum that have checked their guides in the last 6 months to find out of spec in over 50%. How many will it take? if you think your car is fine then thats ok but to say this is a small issue is strange to me

Originally Posted by ramairws6

This is why i keep at it on the issue! In reguards to number 6. He will not answer the question us "valve crusaders" keep asking, if it is a valve concentricity problem why have not ONE head shop that redo these heads for the said issue see a problem with valve concentricity!? [...]

Originally Posted by '06 Quicksilver Z06

[...] But there are other experiences and opinions which are just as valid and have just as much merit deserve just as much consideration as do Katech's. [...]

Originally Posted by Mark200X

I'm sure there is, but yours is not one of them.

But neither is mine

Originally Posted by Mark200X

....

Also, I would like to stress clarity when reading what others wrote (and, to constructively criticize, clarity of writing for some): Disagreeing on the root cause of the issue does not = disagreeing that there is an issue.

Originally Posted by '06 Quicksilver Z06

Funny you mention that, because I'm looking at your continued insistence that the valves can't be the problem [...]

Originally Posted by hoefi

For the record I am a regiestered professional engineer. My engine dropped an exhaust valve back in September 2009. I stripped my own engine down and did my own investigation when GM denied my warrantee. I am the first person on this forum officially reported abnormal guide wear measurements back in January 2010. I provided meaurements, X-Ray, NDT test results to GM even before z0sickTanner started jumping up and down here telling everyone there is an issue with this engine. Do I have data??? Yes, I have data on ONE failed engine. Now, my question to you is, have you examined ANY failed LS7 engine yourself? If not, you have ZERO data compare to my data.

I was at a seminar many many years ago. The lecturer is a geneticist. He made the comment that when he is standing there in front of the large crowd, all he sees is mutants in front of him. I have read your previous posts, and your take on this valve issue is always a vibration one. I guess it's similar to the geneticist seeing only mutants in the crowd. The important question is that have you examine a failed engine as a first step in investigating the problem. Katech has the same issue. Three years ago, they said there is absolutely no issue with the LS7 engine because they have not seen any issue. Twenty months later, they changed their tone and said there is abnormal wear in the valve guides because they are starting to see it. But their comment then was that they have not seen any dropped valve even with the valve guide wear, so there is no danger of dropping valves. In additon, they also said the issue is only contained to a small segment of the population (because that's what GM told them and Katech took that at face value). Now, the last few days, Katech is saying that they are seeing valve guide wear in other model years and confirmed valve heads will fall off with excessive guide wear. All because they are now seeing them. Great, so if you haven't seen something, that something does not exist. Data is great, when it is YOUR data. Someone else's data or observation is not relevant I guess, especially when one considers himself an expert.

Three years after the official start of this valve drop debate and we still have people here convinced that it is less than 1%. I am just shaking my head in disbelief.

I don't post much these days any more. I let Quick do the posting since he is much more effeicent in doing it. My Z has put on about 10,000 miles since the new replacement engine. New heads from WCCH will be going on once they arrive. Should be ready for the road again very soon.

Originally Posted by '06 Quicksilver Z06

[...] Just because I've in the past referred to the stock valves as "crap", does not = they are "defective".

Originally Posted by Mark200X

Can you quote me on that?

Originally Posted by Mark200X

... You insist the valve is the problem, so tell us what's wrong with it.