MarkC

You can add me also. 07 with 21000 miles. All exhaust and three intakes were out. Worked through Vengeance in Feb. 13. I now have 5000 miles on the fix with no issues.

john_g_46

Digging this info out had to take some time. The contrast between the two threads is striking.

Currently have 108,000 miles on my Z06 ... 20,000 since I rebuilt the heads. Re-used original valves. After polishing them, all were still within spec. Went with silicon-bronze guides and Yella Terra rockers ... everything else is oem. No issues since rebuilding.

ctsv510

Added

It did take some time, Ricky definitely pulled a chunk out for me and most of the rest I found via google site: searches.

I agree on the contrast. Many people think their car is fine because it hasn't had a failure, yet if you compare those that have actually measured or inspected the guides, it is 10:1 out of spec vs in-spec.

I'll be on one list or another in a couple weeks.

'06 Quicksilver Z06

Glad to help, and glad to see how informative this thread has become.

Your thread is positioned to become one of the top threads on this subject matter.

EX1 got 16K miles out of his stock guides. He appears to have initially swapped out his stock exhaust valves for SS valves, but kept his stock guides.

http://forums.corvetteforum.com/c6-z...post1583165561

http://forums.corvetteforum.com/c6-z...post1583278595

The part above in italics is of significance.

I have a tendency to first "review the literature" as an initial step in any research endeavor. So as it stands, the "literature" in here on this matter, is in the form of posts.

One can go back into the archives of this forum and get a feel for what was going on during a given point in time.

Attitudes about the issue, what was knowns about it, steps at management, and the evolution of techniques and steps at evaluating and managing it, what was available to manage it, how outcomes were evaluated, rough evaluations of correlation between predicted outcomes and actual outcomes, (in other words were there reports things blowing up after the utilization of certain techniques), etc.

During my own research into the history of the LS7 Valve issues, and efforts to manage it, I have discovered quite a few things, and steps at management.

One was the practice of simply replacing the stock exhaust valves with solid stainless stemmed units, and never bothering to check the condition of the guides.

In some cases, even the stock springs were re used afterwards, or a new set of stock springs were used.

Steps that many would not consider today.

This thread/post is from approximately 4 years ago and if you review the literature from prior to then, and up until now, you can get an appreciation of how this matter, specifically it's management, has evolved over the years.

It is worth mentioning that this approach, or variations of it, had been in use even prior to this thread.

http://forums.corvetteforum.com/c6-z...post1572748187

A review of EX1's posts indicate to me that he may have gone this route.

http://forums.corvetteforum.com/c6-z...post1573423615

At any rate, he mentions that he was running SS solid stemmed units, in stock valve guides, and it did not take long for his guides to wear out.

The other interesting thing of course is that he doesn't say if the condition of his guides had been checked before the SS valves were put in, and so he may have already been near out of spec anyway and not have known it.

4wheels

I noticed you already have me on the list, but are missing my mileage. My car had ~31,000 miles when we found the problem.

I have a video of the play after we removed the heads. I'll see if I can edit the size down to something manageable & send you a link to it.

Also are we only posting results from members of this forum? Some of the other local cars that I've seen with worn guides aren't active members of the forum.

'06 Quicksilver Z06

One more.

10k miles, 2009 stock Z06.

http://forums.corvetteforum.com/c6-z...post1582571781

ctsv510

Updated your mileage.

Yes, we are only including forum members. I too know of others that could be included but it would only be cause for arguments on the forum about potential false information so we can't go down that road. That is why I post a link to each of the posts that state the out of spec guides so that it is clear where and why those on this list have been included.

moose.b3

2008 Z06, 40,000mi, stock, heads replaced by Able Chevrolet.

propain

Interesting. So at first inspection your guides were in spec when they were done by WCCH? They must have been, I am sure WCCH wouldnt send you on your way with out of spec stock guides. What was the mileage at that time?


Seems like you should be on the other list before adding the heavier exhaust valves when you didn't need to.

'06 Quicksilver Z06

Glad to hear that they got you back on the road, but particularly glad that they no longer do things the same way that they did almost 5 years ago, and have gotten better at managing the issue since that time.

Vette @ 71

Your choice of the word "managing" seems to underscore you do not believe bronze is part of "the fix"..

'06 Quicksilver Z06

Since all engine parts have a finite life, and none will last forever if used, how many years would they have to go before they pass "managed" status and go to "fixed"?

That answer is going to vary from one owner to the next and his period of ownership, or even his planned period of ownership, and what he personally considers to be a reasonable amount of time of service, are among many things which are liable to to play a big role in his perspective.

Vette @ 71

Be honest, I am offering this scenario as illustrative, have you ever heard a car owner say I am going to manage that fuel injector problem vs. I am going to "fix" that fuel injector problem?

You manage when you have no solution. Band aids

'06 Quicksilver Z06

Be honest, I am offering this scenario as illustrative.

A guy's clutch is worn out.

He puts in a new one.

Did he "fix" his clutch problem? (there is no wrong answer)

Or is he simply good until he wears that new clutch out too?

Eventually valve guides and valves can wear out. Just like clutches.

As to the guy with the new clutch, well, he is probably hoping that the new clutch either lasts longer than his old one, or is at least better capable of standing up to any additional modifications done to his car than his prior clutch was, or any hard driving or "abuse", than was his prior clutch.

Vette @ 71

How often have u heard of a clutch wearing out?

How often have u heard of valve guides wearing out?

Not remotely relatable or logical in this discussion.

In the absence of a solution or "Fix", you manage till you have a solution or "Fix"..

adamgl

Well GM isn't exactly helping to find a "solution" other than give you the exact thing that has a good chance of having the same problem.

'06 Quicksilver Z06

Thank you for pointing this out, because this tends to escape some of us.

Vette @ 71

Do you have some evidence that validates this?

'06 Quicksilver Z06

What happened is that your argument just got shot down.

It doesn't matter how many times any of us have "heard of it".

A clutch is a wear item.

Valve guides wear over time as well.

http://ls1tech.com/articles/gm-issue...e-wear-on-ls7/

Valve guides are an internal engine component subject to wear over the life of the vehicle. If there is excessive wear (beyond the indicated service limit) after the investigation is completed, GM will cover the inspection and repair expense for vehicles covered under the Powertrain Limited warranty.

adamgl

Other than all the motors that have blown and the all the low mileage heads out of spec on this list so far???
How can the "new" GM heads be any different if they haven't changed anything or even admitted there is a problem?