Originally Posted by jimman

Will this ever end, on and on and on. My conclusion is you F'ed your motor and you want someone to pay for it and it took you a long time to do it. I guess with over 140K on mine I'm sitting on time bomb where the clock must have hung up.

Originally Posted by My07C6

How hard do you drive your Z06?
Do you do wide open 7,000 rpm shifts? If so, how often?

Originally Posted by Doc V.

Here's a link to the 2007 Corvette Owner Manual: http://www.c6registry.com/Technical/...07corvette.pdf

I can't find the information (highlighted in red) to which you've made reference, hoefi. In fact, only pages 290-1 contain references to "racing or other competitive driving," and the information on those pages doesn't focus on "REALLY high speed driving" or on the steps necessary "to extract full performance out of the car by shifting at redline." (Page 333 identifies the Z06's "racetrack-ready dry sump engine lubrication system.")

Are you making reference to a different document--one which contains those "multiple sections?"

Originally Posted by hoefi

My Canadian version that came with the car. We get a french version too, do you want to see that one too :

[IMG][/IMG]

Originally Posted by bass mechanic

my car doesnt have a shift light, only a 1-4 shift indicator are canadian cars different?

Originally Posted by hapnermw

If you don't trust the dealership to measure the guides then ask them to have it done by a third party. Either way you should request a record of all measurements, not just a general pass-fail.

There is no interpretation here. GM has publicly specified the allowable valve guide tolerance. Either a guide is in-spec or it isn't. I believe someone posted the allowable tolerance in one of these valve separation threads.

Originally Posted by EViL427

My car has it in the HUD when it is in Track mode. Thus, all cars have it.

Originally Posted by bass mechanic

i have been running my car in track mode most of the time, i have never seen it, is this a warning rpm inticator or a fuel efficient time to shift indicator and where is it exactly? on track 1 or 2?
mine is an 08

Originally Posted by AirBusPilot

But making the bizarre claim that GM is tuning the LS7 rich to avoid a hot exhaust valve is ludicrous. As I stated, ALL LS motors are tuned rich from the factory.

Originally Posted by bass mechanic

If GM reads these posts to use the evidence in court then i would think it is fair to say that they are WELL aware of the LS7 failures.
initially i was thinking to myself they must be at least a little concerned about the problem. however as others have stated there are few cases of unmodified engines having failures. it seems at least from what i have been reading most of the failures have occured on modified engines or engines that have been used at the track. since they can only be replaced under warranty GM's only option is to place blame on hoe the owner uses their product despite all the info you have presented about their written information that the car is a race ready built car.
understand i am in NO WAY trying to take away from the issue at hand that this does happen to totally stock motors.
the point i am trying to make here is that if GM is watching thease posts and is aware that stock engines have failed. that in thoes cases with some poking and prodding end up replacing a motor under warranty. you would think they would either come up with a solution or a recall or at least a service bulliton.
but i guess since the number of failures are so small on un modified engines maybe the cost to send out a recall with a fix would be far in excess of cost than dealing with a warranty on only thoes customers who experience an engine failure on a unmodified engine. it is also clear from your pictures that they sent out someone to basically try to diffuse the situation and deny your claim rather than man up and honor their warranty.
i think it all comes down to dollars and it seems to me that GM will always take the path that cost the least amount of money, rather than the path that creates the most amount of customer loyalty!

so GM if your reading this post why don't you make a comment for us and share your opinion? do you not see what a mess of things your making? as these corvettes reach their 5 year 100,000 mile warranty starting in 2007 you have 1 more year to start dealing with this mess. and with the 2011 and i believe 2012 corvettes comming off the line with the same engine this problem will haunt you for a good while longer. you cannot simply deny every claim. sooner or later there will be somthing in the news about your company and it's failure to simply honor the warranty. do you want to get in the public eye like toyota did for the floor mat recall? or their prius issues?

and to Hoefi, i think it is great your bringing all of your findings to light. but i think the best service you could do for the corvette community would have been to share your story before and during your court battle with the media. not only would they love to make a story on it but it would definitly get GM's attention and instead of dealing with you as an upset customer it would likely create a lot of negitive PR for GM and it seems companies like this only react wien their name gets drug through the mud in the public eye.
i think that if GM was faced with the thought of loosing sales due to totally stock engines failing and GM unwilling to warranty the engine if you race the car on a track it would definitly limit the number of people considering the purchase of a new corvette, and give GM a black eye in the eyes of the publis looking to buy their product knowing the company wont stand behind their product.

look at hyundai, they offer a pretty amazing warranty.. i wouldnt consider running out and buying one, but it does make me feel like they arent such a peice of crap car as i used to think. at least people who buy them have the feeling the manufacturer will stand behind the product and last i checked they have been selling a lot more cars then they used to.

Originally Posted by 40YRW8

In spite of all the arguments as to how much heat is too much and splitting hairs on proper fuel mapping, one thing has become clear to me. NO ONE has reported taking apart a new LS7 head and reported on the valve guide clearances. This means that we can't assume that the out of spec guides were worn for any reason. They could very possibly been mis-machined at the valve guide factory. If we had a heat/wear problem, we would see fairly similar problems on all of the exhaust valve guides. Not necessarily the same specs but at least a noticeable wear trend. Hoefi has 2 guides that are way out of spec at almost the identical measurement. The other 6 are virtually perfect. I re-read the GM representative engineering report and I agree that the small amount of metal transfer from the guide was due to the final few passes of the stem through the guide after being bent by the valve head failure. With the information presented here, I personally feel that GM's valve guide supplier mis-machined two of his guides and has a quality control problem that caused the valve head to rattle in the guide, land offset to the seat and fail due to (and no one has mentioned this as a Non Destructive Inspection Test) metal fatigue at the flex point of the stem which is between the valve head and the part of the stem that rises short of the bottom part of the guide. I think that also explains why some cars have failed valves at low mileage and no racing. I think that is also why some engines as Katech has said have shown massive valve guide wear in low mileage engines. Remember, when an engine guy pulls apart a head and sees that the guides are way out of spec, he really doesn't know if they are worn or they were out of spec at assembly. We only assume that they were in spec at assembly but we don't know for sure so an assumption as to the cause can be misleading based on erroneous information. The GM engineer has no information to support his position that there was no manufacturing defect that contributed to the failure since he doesn't know what the actual (not specified) valve guide clearance was to start with. Anyway, I keep reading and I still keep coming up with my conclusion that the guides were MOST LIKELY but not positively bored incorrectly at the factory. That is the only conclusion that I can see that would show 6 perfect guide bore diameters and two guide bores that were way out of spec but almost identical to each other. A Non-Destructive Inspection of the two valves that came out of the two bad guides could show why the broken valve broke and if the good valve is near a metal fatigue stress point. Either way, hoefi should win his case.
Good Night!
Gary

Originally Posted by '06 Quicksilver Z06

Agreed that is possible. But why would his, at 140,000 miles, be in spec, and the next car with 10,000 miles on it have valve guides which were out of spec?

Also, and to throw another fly into the ointment, I wonder if you took the heads off of 100 brand new LS7s if all of the valve guides would be in spec.



Well, one can still hope, but it's not looking promising Rock.

This saga of a thread, when it's all said and done, and it finally is wrapped up, we are not likely to be any closer to an answer than we were before.

We will have a few more theories though.

Originally Posted by jimman

It's driven as hard as any out there, I am on my 12th set of tires if that helps. Car has been tracked, I have videos.

Originally Posted by 40YRW8

In spite of all the arguments as to how much heat is too much and splitting hairs on proper fuel mapping, one thing has become clear to me. NO ONE has reported taking apart a new LS7 head and reported on the valve guide clearances. This means that we can't assume that the out of spec guides were worn for any reason. They could very possibly been mis-machined at the valve guide factory. If we had a heat/wear problem, we would see fairly similar problems on all of the exhaust valve guides. Not necessarily the same specs but at least a noticeable wear trend. Hoefi has 2 guides that are way out of spec at almost the identical measurement. The other 6 are virtually perfect. I re-read the GM representative engineering report and I agree that the small amount of metal transfer from the guide was due to the final few passes of the stem through the guide after being bent by the valve head failure. With the information presented here, I personally feel that GM's valve guide supplier mis-machined two of his guides and has a quality control problem that caused the valve head to rattle in the guide, land offset to the seat and fail due to (and no one has mentioned this as a Non Destructive Inspection Test) metal fatigue at the flex point of the stem which is between the valve head and the part of the stem that rises short of the bottom part of the guide. I think that also explains why some cars have failed valves at low mileage and no racing. I think that is also why some engines as Katech has said have shown massive valve guide wear in low mileage engines. Remember, when an engine guy pulls apart a head and sees that the guides are way out of spec, he really doesn't know if they are worn or they were out of spec at assembly. We only assume that they were in spec at assembly but we don't know for sure so an assumption as to the cause can be misleading based on erroneous information. The GM engineer has no information to support his position that there was no manufacturing defect that contributed to the failure since he doesn't know what the actual (not specified) valve guide clearance was to start with. Anyway, I keep reading and I still keep coming up with my conclusion that the guides were MOST LIKELY but not positively bored incorrectly at the factory. That is the only conclusion that I can see that would show 6 perfect guide bore diameters and two guide bores that were way out of spec but almost identical to each other. A Non-Destructive Inspection of the two valves that came out of the two bad guides could show why the broken valve broke and if the good valve is near a metal fatigue stress point. Either way, hoefi should win his case.
Good Night!
Gary

Originally Posted by hoefi

Since the lawsuit is over, I can now cut part of the guides off and send them out for testing. Interesting to see if there is a difference between them. Didn't want to destroy them earlier because of the lawsuit.

Originally Posted by Hirohawa

The lawsuit is over? What where the results? I must be reading this thread wrong as I thought it was in progress from your part 2 update.

Originally Posted by tim414

No, he is posting in parts because it was over and extended period of time.....

If you read the post his suite is over. GM settled (4) days before the court date and honored the warranty.

One of hoefi's issues and part of reason he is posting his experience is that GM 'never' was interested in doing the 'right' thing here (according to hoefi's suit) and did not care to find what the issue really was/is.

In his claim he states that GM advertise(s)(d) the Z06 as/is a "track-ready" car. The issue since they claim it's track ready-worthy is that they "refused" his warranty work in his failed engine after having 'tracked' his Z06. (There is another post-NOT by hoefi-that also claims ZR1 advertised in same way-I mention because there seems to be confusion by some following/reading posts here and interupting info as being stated by hoefi-and NOT the case here).

To note, hoefi NEVER claimed that he did NOT track his 'Z as well. I think that is also a point of confusion. He (hoefi) states from go that he has a long history of performance under his belt and is in the know/experienced in this area.

His contention is that his LS7 had a 'heart attack' at 11k miles-took it for warranty work-was refused by GM his warranty-his contention that GM markets Z06 for street OR track......

The point of his post has been to reveal the above and hopefully find the cause for the benefit of members of this Z06-LS7 forum-

As I have read these post(s) I now see that QC could be suspect/OE maker and/or guides 'could' be out of tolerance from manufacturing......I wonder if the tech guys at Wixom measure the guides before installation?

So far seems like 'more' questions and fewer answers.

To hoefi and 40yrw8......when you say a 'new' LS7....how new/how many miles? Mine has around 7500 miles at present.....is that beyond new (I am supposing it IS)....mine has been to a closed course, but NOT driven in a way which would be considered "tracked". I am a novice and I was getting time behind the wheel for driving-handling the car, shifting-braking etc. highest rpm was maybe 4500 rpm if that so I think it would be considered a track "saftey event" or driver training event". I openly admit my 'Z has more capability than I do.....otherwise my LS7 has seen 5k-5500k rpm maybe 2-3 times (accelerating on street) since 1200 mile break=in....before that it NEVER got above 3800k rpm during 'break-in'. I'm saying this because possibly mine could be examined. But, I do NOT think it fits the bill as "new" LS7 any longer......those days already passed with mine.

Anyway.....remain subscribed....

Originally Posted by 40YRW8

In spite of all the arguments as to how much heat is too much and splitting hairs on proper fuel mapping, one thing has become clear to me. NO ONE has reported taking apart a new LS7 head and reported on the valve guide clearances. This means that we can't assume that the out of spec guides were worn for any reason. They could very possibly been mis-machined at the valve guide factory. If we had a heat/wear problem, we would see fairly similar problems on all of the exhaust valve guides. Not necessarily the same specs but at least a noticeable wear trend. Hoefi has 2 guides that are way out of spec at almost the identical measurement. The other 6 are virtually perfect. I re-read the GM representative engineering report and I agree that the small amount of metal transfer from the guide was due to the final few passes of the stem through the guide after being bent by the valve head failure. With the information presented here, I personally feel that GM's valve guide supplier mis-machined two of his guides and has a quality control problem that caused the valve head to rattle in the guide, land offset to the seat and fail due to (and no one has mentioned this as a Non Destructive Inspection Test) metal fatigue at the flex point of the stem which is between the valve head and the part of the stem that rises short of the bottom part of the guide. I think that also explains why some cars have failed valves at low mileage and no racing. I think that is also why some engines as Katech has said have shown massive valve guide wear in low mileage engines. Remember, when an engine guy pulls apart a head and sees that the guides are way out of spec, he really doesn't know if they are worn or they were out of spec at assembly. We only assume that they were in spec at assembly but we don't know for sure so an assumption as to the cause can be misleading based on erroneous information. The GM engineer has no information to support his position that there was no manufacturing defect that contributed to the failure since he doesn't know what the actual (not specified) valve guide clearance was to start with. Anyway, I keep reading and I still keep coming up with my conclusion that the guides were MOST LIKELY but not positively bored incorrectly at the factory. That is the only conclusion that I can see that would show 6 perfect guide bore diameters and two guide bores that were way out of spec but almost identical to each other. A Non-Destructive Inspection of the two valves that came out of the two bad guides could show why the broken valve broke and if the good valve is near a metal fatigue stress point. Either way, hoefi should win his case.
Good Night!
Gary

Originally Posted by hoefi

Have you ever wondered why GM tuned them so rich (in the 10s I heard, but hey you know what they say about information gathered from the internet). Jason from Ketech also said in one of his previous posts that they run a "very conservative" fuel map (polite way to say pig rich) in their engines.

I do know that one of my race engines makes 100 horsepower per cylinder and I am running in the 10s also. You know why? Because it won't live if I run it leaner. How do I know? Because I blew it up multi times on my engine dyno. GM has nothing to gain by running it richer than necessary. I have nothing to gain by running it richer than necessary, neither does Ketech. We all do it to make sure the hottest component stays cool enough to survive the anticipated usage. That hottest component can be piston top, exhaust valve or any other items that sees the combustion heat. If the exhuast valve is not the issue then there is something else next in line that promted GM to use the rich map. I never said they are using it to hide a design flaw (you said that). I said they run it pig rich as an attemp to keep the valve temperature in check, which is exactly what fuel map tuning is all about. What's so ludicrous about that? I did the same thing as an attempt to cool my piston in my engine, I felt no shame in doing that.

Originally Posted by hoefi

My Canadian version that came with the car. We get a french version too, do you want to see that one too :