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GM response to LS7 valve guide issue summary confirmed

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Old 08-31-2012, 03:07 PM   #1
Short-Throw
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Default GM response to LS7 valve guide issue summary confirmed

Edit #4 -- Chevy Customer Service official post #604 October 11, 2012

Quote:
Originally Posted by Chevy Cust Svc View Post
Hello all,

LS7 Valve guide issue summary:
Affects a small, number of '08, 09 10 and 11 Z06s
GM discovered the condition through our cylinder head warranty data involving a very small percentage of our vehicles.
Through inspection of returned heads, it was determined that a machining error in the valve guide had occurred at our head supplier.
The quality issue has been contained as of Feb 2011 with 100% inspection of all heads.
The most common customer complaint has been excessive valve train noise.
However if the condition is not addressed, it could result in engine failure. To date, where this condition has been observed, it has occurred early in the vehicle life.
What customers need to know: They should drive and enjoy their vehicles without fear. If their car demonstrates this condition, they are likely to hear unusual valvetrain noise first. If you have a concern regarding this issue on your personal vehicle feel free to contact me through private message on this forum and we will work to assist in resolving your concern. Feel free to contact me through Socialmedia@gm.com please put attention Evan in the subject. As always, vehicles that have modifications to the powertrain or the calibrations, are no longer covered by GM's warranty.

Sincerely,
Evan, Chevrolet Customer Service


Edit #2 -- This was originally posted referring to 09 - early 11 models.

Edit #3 as of Sept 7, 2012

The idea of this sticky was to be informational but it turned into a town hall meeting. Nature of forums I guess.

GM will be posting info giving customers a specific method to address any concerns or issues. Once this process is set up, an announcement will be made, hopefully within the next few weeks, but possibly sooner.

Hang in there...


Many of you know my close relationship with Team Corvette and how accurate and truthful my posts are -- those that don't will have to decide for yourself what you do, or do not want to believe. Unfortunately in this high tech age I concede anyone with a keyboard can be a self-proclaimed expert so it's tough to filter out all the misinformation these days.

JVP posted this information in another thread, but it was buried after over 500 posts, so this is for the benefit of many who gave up on that thread, or never saw it.

I was going to post this some time ago but refrained. The recent hysteria over the valve guide issue has been inconceivable as it's come to a point where any failure or issue with the car, even a flat tire was blamed on valve guides.

I posted to substantiate this information is correct.

Quote:
Originally Posted by jvp View Post
I had a chance to chat with one of the engineers at Carlisle about this specific issue. The discussion was fairly focused, and out of it I got the following points (paraphrasing, so forgive me here) ...
  • It sounds like it's affecting a reasonably small number of '09, '10, and '11 Z06s. It's not the cause of any issues that have popped up with the LS7 in prior MYs.
  • GM discovered the problem through their cylinder head warranty data; it went from nearly 0 to a peak of 6.5 problems per thousand engines.
  • They inspected the returned heads and found the machining error in the valve guide. It had occurred at their head supplier. As stated in the thread already: it's not a design issue.
  • Problems contained as of Feb '11 with 100% inspection of all heads.
  • The most common customer complaint has been excessive valve train noise and if left unattended, an engine failure would likely occur. A handful of engines have been replaced under warranty due to these specific failures.

Overall, the engineer wanted customers to: enjoy their cars! If a problem is going to happen, it'll be accompanied by a nasty/excessive valve train noise long before the engine fails. He didn't quantify what "excessive" valve train noise means, as opposed to the LS7's normal ticking.
jas
Furthermore;

If a car makes it through even a fraction of the 100k mile warranty, it is built properly and will have a complete service life.

As far as excessive noise mentioned, it doesn't have to be excessive but more-so not normal or unusual.

If your car is under warranty stop fretting a go enjoy each drive.
If your car is modified you run the risk of spending your own dime for repair, no news here.

There are legitimate failures as with any machine, but there are a countless number of failures that occur due to owner abuse, whether realized or not. In conjunction with the team, I will be providing forthcoming preventative maintenance tips.

The Z06 is a street car, not a race car and if you drive it as such, you have to prep it as such.

Lastly:

Katech has chimed in multiple times with helpful information. If there is an issue, it's not a matter of simply replacing the valves (edit #1 - I had guides here originally and didn't catch the error before posting) like many have suggested, there's more to it and Katech's approach is correct. I'm not singling Katech out as the only shop credible as I know there are other builders, but merely the only shop I can personally vouch for and one that my GM friends approve.


Hopefully this will put a rest to the LS7 paranoia.

I will follow up with any additional questions posed here.


Mike

Last edited by Short-Throw; 10-11-2012 at 11:10 AM.
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Old 08-31-2012, 03:17 PM   #2
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Thanks for this post. Between this one and Katech's recent postings I feel we are righting the ship as this forum has been out of control for the last few months.
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Old 08-31-2012, 03:18 PM   #3
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It's nice to see that we are finally getting answers.
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Old 08-31-2012, 03:20 PM   #4
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Thank you Mike! Hearing that I now hope that the excessive paranoia displayed on this forum will go away and people will get back to enjoying their cars instead of worrying about the sky falling Bottom line, if it happens to your car and it is stock it is covered under warranty, so don't worry about it. If you intend to modify your car then when doing so simply have the shop that you choose to deal with do what the guys at Katech suggest and you have nothing to worry about, problem solved! Now we can all go back to actually enjoying our cars and talking about them on here instead of constantly having to look at thread discussing the possibility that they will break down in the future
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Old 08-31-2012, 03:26 PM   #5
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Quote:
Originally Posted by Short-Throw View Post


As far as excessive noise mentioned, it doesn't have to be excessive but more-so not normal or unusual.

....

In conjunction with the team, I will be providing forthcoming preventative maintenance tips.

The Z06 is a street car, not a race car and if you drive it as such, you have to prep it as such.

...

If there is an issue, it's not a matter of simply replacing the guides like many have suggested, there's more to it and Katech's approach is correct.
Thanks Mike,

A few questions then...

I have a hard time understanding what you mean by "it doesn't have to be excessive but more-so not normal or unusual".

You mean, it has to be 'more than excessive' to be identified as an issue? How could someone determine what is normal, vs excessive vs 'more than excessive'?

I am looking forward to your preventative maintenance tips.

I do agree, this is a street car, not a race car. For a car to be tracked, it needs proper preparation. What exactly would you suggest to prep the car for a track?

You said "it's not a matter of simply replacing the guides like many have suggested", but that is exactly what Katech is recommending. Can you elaborate further?

Thanks.
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Old 08-31-2012, 03:31 PM   #6
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Quote:
Originally Posted by Short-Throw View Post
Lastly:

Katech has chimed in multiple times with helpful information. If there is an issue, it's not a matter of simply replacing the guides like many have suggested, there's more to it and Katech's approach is correct. I'm not singling Katech out as the only shop credible as I know there are other builders, but merely the only shop I can personally vouch for and one that my GM friends approve.
But I interpreted Katech's recent post as exactly that: replacing the OEM guides with bronze is their preferred solution, given the [apparent] inconsistency due to machining inconsistency.

Your post seems to infer that this is not correct - or are you saying that replacing the OEM sintered guides [with new OEM guides] as not being a fix?

Quote:
Originally Posted by Katech_Jason
Nothing changed. I've been saying to replace the guides with bronze all along.
Quote:
Originally Posted by Katech_Jason
The proper fix if the vehicle is out of warranty or modified is bronze guides with Ti/Mo intake valves and OEM exhaust valves such as Katech has been doing all along.
Quote:
Originally Posted by Katech_Jason
WCCH has been doing Katech's heads as dictated by us with bronze guides and Ti/Mo intake valves.

Last edited by Random84; 08-31-2012 at 03:32 PM. Reason: syntax
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Old 08-31-2012, 03:45 PM   #7
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Quote:
Originally Posted by Random84 View Post
But I interpreted Katech's recent post as exactly that: replacing the OEM guides with bronze is their preferred solution, given the [apparent] inconsistency due to machining inconsistency.

Your post seems to infer that this is not correct - or are you saying that replacing the OEM sintered guides [with new OEM guides] as not being a fix?
Sorry, here I am trying to simply and I added confusion.

My mistake, I meant to simply state replacing the 'valves only' was not a complete solution. I will edit, thank you.
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Old 08-31-2012, 03:50 PM   #8
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Hi ST,
Appreciate the post but I must be missing something, I don't quite understand the point of your post.....

So I have a question and maybe you can point me in the right direction...........

So for a person that has a totally stock Z06 (2007) like myself, and uses it for general street driving, what can we do to mitigate the stock rocker arm risk?

I think you are still saying there is some design/build flaw and therefore some minimal risk for guide/rocker failure. So to look at some solution like possibly the Yella Terra rockers to mitigate the valve side loads would make sense. But does that leave you vulnerable to the warranty not being honored even if you don't race the car?

Maybe you could encourage Katech to chime in about the use of these rockers as an aid to maybe not alleviating failures but reducing risk without major engine mods?

Thanks in advance for your Thoughts.
Bob
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Old 08-31-2012, 03:50 PM   #9
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How about I make this a sticky thread and we can direct everyone else here for answers.
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Old 08-31-2012, 04:09 PM   #10
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Answers in red.

Quote:
Originally Posted by Jawnathin View Post
Thanks Mike,

A few questions then...

I have a hard time understanding what you mean by "it doesn't have to be excessive but more-so not normal or unusual".

I guess for an owner who hasn't heard other Z06s run, wouldn't have a baseline to know if their car is normal. Has your engine made a noise over time that wasn't there previously?


I am looking forward to your preventative maintenance tips.

I do agree, this is a street car, not a race car. For a car to be tracked, it needs proper preparation. What exactly would you suggest to prep the car for a track?

There really isn't one list that covers all owners/cars but more of a hierarchy of recommended steps that should be performed before, during and after depending on event, track location, ability, temperature, etc...

I'd be happy to discuss with you in more detail but not sure this post is the best place for it as it will lead to multiple side conversations. Perhaps another thread or you could PM me and I'll call you.




You said "it's not a matter of simply replacing the guides like many have suggested", but that is exactly what Katech is recommending. Can you elaborate further?

I edited my mistake, brain was revving faster than my hands typing. I meant valves.


Thanks.
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Old 08-31-2012, 04:11 PM   #11
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Quote:
Originally Posted by pewter99 View Post
How about I make this a sticky thread and we can direct everyone else here for answers.
It should include Jason's post from the other thread though.. (just a suggestion)
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Old 08-31-2012, 04:19 PM   #12
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Quote:
Originally Posted by pewter99 View Post
How about I make this a sticky thread and we can direct everyone else here for answers.
Fine by me, you're the boss!

Guys, I don't have all the answers on tap, wish I was that smart, just happen to be well connected and can get them. One thing I can say, the Team is committed to keeping everyone happy with past, current and future models. Those that have been to various events over the years have met some of these team members and know how dedicated they are. When is the last time you saw a Porsche exec roll up his sleeves at a track event to change a customers brake pads!

Go ahead and post questions but please be patient as info I don't know will have to be requested and may not come back as fast as we're used to.

Mike
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Old 08-31-2012, 04:28 PM   #13
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The engineers were prepared for these questions when I asked a female GM rep about LS7 failures on Thursday. She said the engineers would address on Friday. My friend and fellow Z owner with an engineering background seemed to get another answer. The GM engineer said that the problem was isolated to 06' and early 07' models. I will get some more info from my friend when I speak to him soon for a more detailed explanation.
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Old 08-31-2012, 04:33 PM   #14
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Quote:
Originally Posted by RFE-57 View Post
Hi ST,
Appreciate the post but I must be missing something, I don't quite understand the point of your post.....

So I have a question and maybe you can point me in the right direction...........

So for a person that has a totally stock Z06 (2007) like myself, and uses it for general street driving, what can we do to mitigate the stock rocker arm risk?

I think you are still saying there is some design/build flaw and therefore some minimal risk for guide/rocker failure. So to look at some solution like possibly the Yella Terra rockers to mitigate the valve side loads would make sense. But does that leave you vulnerable to the warranty not being honored even if you don't race the car?

Maybe you could encourage Katech to chime in about the use of these rockers as an aid to maybe not alleviating failures but reducing risk without major engine mods?

Thanks in advance for your Thoughts.
Bob
The rocker arm problem was 2007 only. For these vehicles I recommend new rocker arms from GM.
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Old 08-31-2012, 04:36 PM   #15
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Quote:
Originally Posted by Short-Throw View Post
Many of you know my close relationship with Team Corvette and how accurate and truthful my posts are -- those that don't will have to decide for yourself what you do, or do not want to believe. Unfortunately in this high tech age I concede anyone with a keyboard can be a self-proclaimed expert so it's tough to filter out all the misinformation these days.

JVP posted this information in another thread, but it was buried after over 500 posts, so this is for the benefit of many who gave up on that thread, or never saw it.

I was going to post this some time ago but refrained. The recent hysteria over the valve guide issue has been inconceivable as it's come to a point where any failure or issue with the car, even a flat tire was blamed on valve guides.

I posted to substantiate this information is correct.



Furthermore;

If a car makes it through even a fraction of the 100k mile warranty, it is built properly and will have a complete service life.

As far as excessive noise mentioned, it doesn't have to be excessive but more-so not normal or unusual.

If your car is under warranty stop fretting a go enjoy each drive.
If your car is modified you run the risk of spending your own dime for repair, no news here.

There are legitimate failures as with any machine, but there are a countless number of failures that occur due to owner abuse, whether realized or not. In conjunction with the team, I will be providing forthcoming preventative maintenance tips.

The Z06 is a street car, not a race car and if you drive it as such, you have to prep it as such.

Lastly:

Katech has chimed in multiple times with helpful information. If there is an issue, it's not a matter of simply replacing the valves (edit-I had guides here originally and didn't catch the error before posting) like many have suggested, there's more to it and Katech's approach is correct. I'm not singling Katech out as the only shop credible as I know there are other builders, but merely the only shop I can personally vouch for and one that my GM friends approve.


Hopefully this will put a rest to the LS7 paranoia.

I will follow up with any additional questions posed here.


Mike
Mike,

What if you car is no longer covered under warranty and low mileage z06?
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Old 08-31-2012, 04:39 PM   #16
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Quote:
Originally Posted by FSTFRC View Post
Mike,

What if you car is no longer covered under warranty and low mileage z06?
I was just going to ask that very question.

I just picked up an 09' Z06 with 11K miles and I only drive about 15K miles a year.

AND, mine seems to have a louder/more pronounced "ticking" sound then other Z06's I have test driven
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Old 08-31-2012, 04:50 PM   #17
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Hey Jason,
Would any roller rocker be better than a stock non roller?
B
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Old 08-31-2012, 04:52 PM   #18
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Quote:
Originally Posted by RFE-57 View Post
Hey Jason,
Would any roller rocker be better than a stock non roller?
B
We find no problem with the factory rocker arms for the applications we are using them in. You have to be careful with "upgrades" sometimes as they can have unknown effects on valvetrain dynamics.
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Old 08-31-2012, 04:54 PM   #19
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Thanks for the info Jason........
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Old 08-31-2012, 04:55 PM   #20
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Quote:
Originally Posted by Turbooo2u View Post
The engineers were prepared for these questions when I asked a female GM rep about LS7 failures on Thursday. She said the engineers would address on Friday. My friend and fellow Z owner with an engineering background seemed to get another answer. The GM engineer said that the problem was isolated to 06' and early 07' models. I will get some more info from my friend when I speak to him soon for a more detailed explanation.
Most of the recent threads I have seen have been 08-09 models.

But thank you OP for helping some of the Chicken Little's sleep better tonight. This Forum is such a small percentage of the cars that are out there. How can anyone assume this is an epidemic?
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