2000FRCZ19

there is more than enough info in the following threads to help you research ls7 failure or exhaust valve issues. the funny part is after all the threads and posts very little new info has been put out there. i think its time to give it a rest for a while guys. unless you have some new info on an exact cause that can be doccumented and proven please dont start another thread on this asking what can be done to prevent it or stating there is a problem. we all know that there is some form of a problem with some of these things but the extent of it hasnt been proven in stone yet, as well as the exact root cause. if there is a design flaw, then find it and post it please. if there is a proven cause that can be avoided then please post it. until there is factual proof, all that will happen is one more debate and pissing contest will start. if your engine fails then have it added to quicks list and provide as much info about the history of the car as possible.
http://forums.corvetteforum.com/c6-z...lly-gents.html
http://forums.corvetteforum.com/c6-z...his-forum.html
http://forums.corvetteforum.com/c6-z...falling-2.html
http://forums.corvetteforum.com/c6-z...ear-video.html
http://forums.corvetteforum.com/c6-z...riven-z06.html
http://forums.corvetteforum.com/c6-z...st-update.html
http://forums.corvetteforum.com/c6-z...ster-list.html
http://forums.corvetteforum.com/c6-z...-fix-sale.html
http://forums.corvetteforum.com/c6-z...revention.html
http://forums.corvetteforum.com/c6-z...er-z-down.html
http://forums.corvetteforum.com/c6-z...cker-arms.html
http://forums.corvetteforum.com/c6-z...in-stress.html
http://forums.corvetteforum.com/c6-z...-13-000-a.html
http://forums.corvetteforum.com/c6-z...a-new-one.html
http://forums.corvetteforum.com/c6-z...ues-again.html
http://forums.corvetteforum.com/c6-c...n-the-zr1.html
http://forums.corvetteforum.com/c6-z...-e-phenom.html
http://forums.corvetteforum.com/c6-z...ad-enough.html
http://forums.corvetteforum.com/c6-z...-problems.html
http://forums.corvetteforum.com/c6-z...zo6-heads.html
http://forums.corvetteforum.com/c6-z...40k-miles.html
http://forums.corvetteforum.com/c6-z...uide-data.html
http://forums.corvetteforum.com/c6-z...e-and-fix.html
http://forums.corvetteforum.com/c6-z...en-shaken.html
http://forums.corvetteforum.com/c6-z...oming-off.html
http://forums.corvetteforum.com/c6-z...st-valves.html
http://forums.corvetteforum.com/c6-z...th-this-z.html
http://forums.corvetteforum.com/c6-z...-chime-in.html
http://forums.corvetteforum.com/c6-z...-failures.html
http://forums.corvetteforum.com/c6-z...or-let-go.html
http://forums.corvetteforum.com/c6-z...uide-wear.html
http://forums.corvetteforum.com/c6-z...is-winter.html
http://forums.corvetteforum.com/c6-z...re-having.html
http://forums.corvetteforum.com/c6-z...es-guides.html
http://forums.corvetteforum.com/c6-z...igh-marks.html
http://forums.corvetteforum.com/c6-z...n-whiners.html
http://forums.corvetteforum.com/c6-z...es-valves.html
http://forums.corvetteforum.com/c6-z...ue-thread.html
http://forums.corvetteforum.com/c6-z...-it-blows.html post #9 caught me off guard just poking fun at ya quick
http://forums.corvetteforum.com/c6-z...lletproof.html
http://forums.corvetteforum.com/c6-z...valve-and.html
http://forums.corvetteforum.com/c6-z...ollection.html
http://forums.corvetteforum.com/c6-z...ke-valves.html
http://forums.corvetteforum.com/c6-z...-pictures.html
http://forums.corvetteforum.com/c6-z...wn-begins.html
http://forums.corvetteforum.com/c6-z...pictorial.html
http://forums.corvetteforum.com/c6-z...the-issue.html
http://forums.corvetteforum.com/c6-z...-problems.html
http://forums.corvetteforum.com/c6-z...ped-valve.html
http://forums.corvetteforum.com/c6-z...ally-ugly.html

VicCaerter

Sticky!!!

'06 Quicksilver Z06

I'm glad you point that out.

We know a little more now than we did almost a year ago.

I made that update thread in November of 2011, about 2 months after that post.
http://forums.corvetteforum.com/c6-z...st-update.html

and have been reviewing the circumstances surrounding these reported failures ever since I put it up.

Hardly a week goes by that I don't review the circumstances surrounding each report in that list.

Sometimes sifting through posts the claimant made months prior to his actual failure report, in an effort to find information about modifications or any other pertinent information, which went unreported in the initial tale, but were clearly present and indicated in posts days, weeks, or even months prior to the claimant's actual report of the failure.

That is why the size of that list has fluctuated.

Reviewing the posts of the claimants, I have been able to go back and in multiple instances, obtain dates of failure, what motor oil was being used, how many track days, how many owners the car had, the reported "cause" of a dropped valve (broken rocker, broken valve spring, or broken valve) when it was reported to have occurred .....just about everything except build dates, which I will be hunting down next.

In reviewing the reported failures I was shocked to see that while "dropped valve" is what everyone likes to talk about, better than half the 50 stock cars which failed did so due to oil starvation or oiling issues, head gaskets, piston failure, or lifter failure.

So we know a little more now than we did, due to a more in depth and thorough review of the reported stock failures that we have.

That careful review leads me to believe that there was a problem with some of these engines, perhaps a QC issue, but 2009 and up models do not appear to be affected, and not all '06-'08s are either.

Finally, I also use to think that the threads did not glean any new information. For the most part that's true. But every now and then, and it may take over 100 posts in a thread for it to happen, occasionally some new information will come out in them, just other pieces of the puzzle, some of which even dovetails.

http://forums.corvetteforum.com/c6-z...post1581360893
http://forums.corvetteforum.com/1581349709-post335.html
http://forums.corvetteforum.com/c6-z...post1581199882
http://forums.corvetteforum.com/c6-z...post1578667842
http://forums.corvetteforum.com/c6-z...post1580428954
http://forums.corvetteforum.com/c6-z...post1570943338
http://forums.corvetteforum.com/c6-z...-13-000-a.html


Hope that helps.

2000FRCZ19

I saw it was an early post and It is funny how as time goes on and after all the research we do see things in a different light. at first I was convinced the ls7 was a time bomb but I have since changed my view of it. the number of stock unmodded untuned and nonraced failures due to valves appear to be low. could be qc or supplier problems on select cars. I could not resist poking fun at ya over that post. its all in fun.

'06 Quicksilver Z06

Yep, I knew it was.

bowmanized

'06 Quicksilver Z06 ****

Random84

So basically we need a few more "I'm not going to read or search, so spoon-feed me on the best fix for my LS7 timebomb?" threads, right?

Quick Silver Z

So the Cliff notes are - this could happen to any LS7 but odds are it won't - the bigger the cam and the harder you beat on it increases the odds.

Correct?

JoesC5

I just wish that someone from GM would tell us what the difference is(if any) between the 2006-08 and the 2009-13 exhaust valve is and, if there is a difference, why the change was made.

MVPJEFF106

Although newer and less miles, has anyone reported newer (10',11',12') with this issue? I watched a video on here with the heads off and a spring comparison where they were even different colors. Just curious if this only applies to earlier years.

'06 Quicksilver Z06

There appear to be two reasons why the broken valve matter is so frequently discussed.

1.Modified cars which suffered this sort of failure are typically subconsciously included along with stock failures. Indeed, this is arguably the largest reason why the LS7 is linked to dropped valves.

Cammed cars are particularly likely to be reported, and this forum has right at 40 reports of cammed Z06s alone which failed, many due to dropped exhaust valves. When these get lumped into the stock statistics, then it is easy to see why we are seeing what we are seeing.

2. Old reports of oil related track failures, much more common in MY 2008 and prior, are lumped in with these valve related failures.

I think in the early years, many of the failures were oil related and they are included in the "dropped valve" statistics, because people typically instantly conclude that every LS7 engine failure is the result of a "dropped valve".

There are no reports found on this forum of engine failures in 2010-2013 cars.

A rough count, of engine failures in the stock C6 Z06 failure listing which includes 2006-2009 stock cars discussed on this forum shows a breakdown of the failures in the following categories:

22 Oil related (oil pump failure/bearing failure/seized reports.) These typically, but not always occurred on the track.
2 Piston related failures
1 headgasket
1 lifter

That totals out to 26 cars and is more than half of the 51 stock failures. The total count dropped as one car on the original listing was found to have been tuned, another car removed from the listing, suffered what was described as a "bent valve" likely due to a spring failure. The car was purchased used and the owner returned it.

Continuing with the tally it was found:

1 broken intake valve spring.
9 broken rockers or broken valve springs
11 dropped valves
4 unknown

Considering all 11 of the stock "dropped valve" cars reported to be "broken valves", not due to a broken valve spring or a broken rocker, the breakdown on this forum is:

2006 stock cars total of 2 . 1 in the U.S, 1 in Europe??. Both on the street.

2007 stock cars total of 4. All in the U.S 2 on Street, 2 on Track.

2008 cars 5. All in the U.S. 3 occurred on the track. 1 occurred on the street in a car with 8 track days on it, 1 the owner does not report street or track. One car had over 80K miles on it.

What you end up with, on this forum is in stock cars, are 11 instances of broken valves not due to a broken valve spring or broken rocker arms. 5 reported to have occurred either on the track. One of the 5 with over 80,000 miles on it when it suffered an on track failure. 1 reported in a car which had 8 track days on it, but ultimately failed during street driving. 4 which were said to have occurred on the street. 1 with an unlisted history or place listed where it failed, street or track.

It is worthy of note that a few members suffered more than one failure, so the that there are actually more "instances" than cars involved.

Mopar Jimmy

Of course you will still get new threads posted up for the exact reason stated above.

This thread unfortunately will not change the ridiculous amount of constat never ending repetitive threads on the topic at hand.

Another one already posted today after this thread went up.

2000FRCZ19

i agree nothing will change. too bad. here is a link the the one that was posted after this. http://forums.corvetteforum.com/c6-z...e-failure.html

it is headed in the same direction as all of the others before it.

LS7 BUD

Quote:
Originally Posted by '06 Quicksilver Z06
Some of these reports have convinced me to not stay in this car for the long haul either.

I intend to keep driving it like I always have. But I'm looking for the exit ramp too. Doing my due diligence now



Whoa I'm shocked by this... What made you change your mind to keep the car? Gimme the short form of it... Will you be one of many looking to get into the C7 once the 2nd year of them are out and the bugs have been worked out...? Just wondering...

HyperX

reread this thread and you will know.

NYOverlord

Hi there,

I read your post that "better than half of the stock cars that have dropped valves are due to oiling issues or head gaskets..."
-I'm about to use 89 gram stainless steel exhaust valves and thinner head gaskets that will bring my compression up to 11.55:1. This will be on Texas Speed Performance's PRC 265 Street heads with dual valve springs rated at .675 and bronze guide on a KaTech Torquer 110 camshaft.
-Do you think that might cause me to drop a valve or destroy my journal?

Best regards,

Jordan

Fabio-Z06

Vette @ 71

1 will not do it. at a minimum..

'06 Quicksilver Z06

I believe that I said "better than half the 50 stock cars which failed did so due to oil starvation or oiling issues, head gaskets, piston failure, or lifter failure."

Any further advice that you seek on this matter, I suggest that you speak to a cylinder head professional or cylinder head professionals, and make your decisions after evaluating their advice, and experiences.

NYOverlord

No clue what Vette 71 and fabio mean by that.

Quick- thanks for the advice, but I've already asked several tuners and LSX distributers and builders. All said its fine except Jason at KaTech.
That's why I figured I'd get your thoughts on the forum.