Tech

As I've told you already, the GM claims are *highly* questionable and *incomplete*. If you pay attention, even with purely objective analysis, the number is likely much higher than 150 engine failures. It could reasonably be an order of magnitude higher.

Even if it were 5% of engines, or 20% of engines.. that doesn't mean every person should proactively replace the guides. You and I may agree on that. However, the moment you repeat 0.5%, it's clear to me that you either haven't done your due diligence or you refuse to consider data from car owners, tuners, engine builders, machinists, etc. In either case, your head is buried in the sand.

AzDave47

This is the company that says only MY09 to Feb 2011 are affected - must be real good data they have. ie, we managed to screw many customers out of replacement with low mileage cars that had short warranty (5-100 didn't come until later).

Stig13

I'm guessing LMB-Z watched "The Neverending Story" before creating the initial post here... And yet here I am perpetuating.


There will always be 2 parties in these conversations and it's rare if ever that a person's opinion will be swayed to the other side. For this reason I don't care whether Tony feels there is a correlation or enough data to back it up - it's his choice what he wants to do. The losers are those who blow an engine without a warranty and chose not to perform their due diligence with the information provided. Tony agrees that it's worth his time based on the current info to check his guides at warranty end which is smart and prudent regardless of which side of this fence you're on.


One of the main points of contention is whether users on this forum tell new LS7 owners to go straight to getting their valve guides addressed. This point has been misinterpreted. Tony - I have seen posts specifically stating "just go get your valves done by a reputable shop" but that is a recommendation/opinion which everyone is entitled to. It's up to the owner to decide whether it's not out of spec enough, they're OK with the data they see or don't see, or to get it fixed.


Personally, knowing there is not and never will be firm data, I will have the check done close to warranty end. Even to a logical minded, proof-driven engineer (which I am not), there is room for reason and assumption outside of cold hard indisputable facts on any issue. Initially I thought if they are not out of spec or just a little out I would let it be. The more I see OUTSIDE of this forum, and being averse to the potential risk and bill that could come due to failure, I've changed my position and will be prepared to have the heads taken care of regardless. I am averse to being one of the even 0.5% failure rate if I could have done something about it that I feel logically improves a known defect, but that's me. The goal is to also add a cam and headers at that time because if I have the cash why not, so that's another reason just to have more peace of mind and security.


I can almost guarantee (sorry, no solid data here, either )that if someone in Tony's camp were to blow an engine tomorrow and the shop/dealer handling it were to say it's because of a valve guide it's not going to change their opinion on whether all out of spec guides should be addressed because there is a risk. To those that are still trying to change minds on both sides, go for it but with all the related threads just on this forum alone don't expect to change anyone. It's not worth anyone getting butthurt over on either side, and that's what seems to be happening, like a political conversation. Stay frosty, my friends!

SocalChvy

MANY potential owners have been advised to get their heads fixed if they were looking into getting a Z06. Some have referred to the cylinder heads as ticking time bombs. And that's fine. But YOU can't speak for everyone. By saying "no one" you are assuming yourself as some all knowing forum poster who has monitored every LS7 cylinder head conversation that has taken place here. Don't take that route. It's TOO EASY to prove you wrong.


I never said the cylinder head issue was a fairly tale. My position is that it is up to each owner to decide which route they want to take and that this forum, absent of absolute fail rate data can sometimes give doomsday forecasts. I purchased an aftermarket warranty and was bashed for that.

So now you are admitting that some people have told others to fix their cylinder heads? Precautionary not or not, my point was that the advice has been given.

How many? You must live in a part of the U.S. where countless Z06s are dropping valves...wow. How many were stock vs modified?

Who said anyone was lying?


Is Katech the only entity that replaces cylinder heads? No. But you narrowed it down to them huh? Talk about strawman argument. Wow.

Can you speak to every shop and every tech that has advised an LS7 owner swap their cylinder heads? No. You. Can't.

Can you also validate every home-done wiggle test performed by every owner? No. You. Can't.




Please stop speaking for everyone. You have not the details nor the data to attest to every interaction that has occurred on this forum.

A guy simply asked for the data on LS7 failure rates, and that turned in to a 9-page thread of bickering but no one had actual data or facts.

"Countless" "a bunch" "a lot" "Several"

Are not accpeted.

LMB-Z

WOW!!!!!!!!!!!!!!!!!!!! Once again, I apologize for starting this thread. I wish one of the mods would just close and lock it. I am so sorry, I did not mean to start an argument.

Its your car, you do what you want to it, when you want, and how you want. If it blows up, don't come complaining about it. I hope they all last forever.

Mods, please close this thread.!!!!!

Tonylmiller

Actually I would like to hear your estimate, and everyone else's. I have not heard of very many failures.

Tonylmiller

You can stop apologizing. I think 17 apologies are enough for one thread. We get it.

LMB-Z

Well, Mr. Data...you should go back and look at previous posts. I don't think I would let you build me a sandbox, much less a rocket. 17 posts??? And last time I looked, this was my computer, my thread, and IF I want to apologize 17 times, I will. It was only 3, so if you need more DATA, go back to page 1 and start all over again. Just so you will know, I apologized on post #106, 126, and the last one was #185. I research my DATA, why don't you?

MTPZ06

Nah...you got bashed for your approach and demeanor in that thread.
https://www.corvetteforum.com/forums...ut-valves.html

And then this thread... https://www.corvetteforum.com/forums...ly-amazed.html

Nobody is getting "bashed" for simply purchasing a warranty.

We know who you are. Forum name "Datrojan" wasn't working out for you anymore huh?

Dan_the_C5_Man

On the point of Correlation vs. Causation..

SHOW ME ONE example of a failed stock exhaust valve in a head that did NOT have worn guides past the service limit, PLEASE.

Again, common sense is not so common. Time to update the ignore list.

And for the record, most of us "valve guide alarmists" could care less about anyone's engine in a car owned by "valve guide deniers" such as Tony and others like him - you are consciously making a decision to ignore the issue and potential failure..

We are passionate about informing new owners that don't understand the issue, in an attempt to STOP the cycle of failure, just as one would teach a child that running across a busy freeway could result in being hit by a car. If they choose to continue to play in traffic, nothing can be done. BUT if these same people advise OTHERS that "statically, a car probably won't hit you this week, so go play", that's when we get "excited".

That said, I am running late; I need to get to the bank and deposit my latest batch of cylinder head repair vendor kick-back cheques..

Tonylmiller

The technical term is hyperbole. I was obviously exaggerating for effect.

OK you can lighten up now, and I do think 3 times is enough. This is only a message board, ok?

​

Tonylmiller

Unfortunately I do not have data on all failed engines. I do think, however, that all failed engines had bugs on the radiator. My point is, if all engines have the condition, you can't really draw any conclusions about cause from that data. If we were to do some controlled experiments in which some engines had good guides, we might be able to tell something.
Do you agree that the LS7 appears to be tolerant of worn valve guides? There are quite a few engines out there with high miles, still going strong. It seems to be the consensus that the vast majority of LS7 engines have worn guides.

Mordeth

The bolded part above is your best bet Dan. It does kind of suck that the forum still shows me ignored users posts if someone quotes them though. But I can live with this small horror for the sake of trying to help others. I've had the good fortune to add three individuals to my ignore list this week. Two here and one in the C7ZR1 section. Makes things so much nicer this way.

The primary issue is that often times we are dealing with someone who is ignorant of their own ignorance, mostly due to lack of experience in actually working on cars and understanding valve train dynamics. They are smart, intelligent individuals that are experts in one field but this unfortunately works against them if they attempt to understand other complex fields on a superficial level. They think they know the right approach because it works elsewhere and so they back themselves into their own corner and then dig in due to pure arrogance, stubbornness and hubris. They refuse to recognize or even acknowledge other legitimate forms of evidence and the entire cycle becomes a giant logical fallacy, compounded by stubbornness and reinforced by their own high intelligence - which again is working against them due to over-confidence. Their own arguments become recursive and their conclusions self-fulfilling. Best bet is to simply ignore as they will never give up, never give in and never acknowledge they were wrong (at least it is rare).

If you have never seen a worn guide or what it does to a valve, or have never seen a snapped valve injested into a block or have never even changed your own oil then it is unlikely you understand why allowing severely worn guides exist in a high revving, already relatively unstable valve train is folly.

- GM themselves will warranty a set of heads if the guides are beyond service limits. Why do you think this is? Because they know that the motor can fail as a result and cause a much larger bill.

- Aftermarket warranty companies will pay to fix heads if it is found that guides and valves are beyond service limits. Why do you think this is? Because they know there is a direct, causal relationship between guide wear, valve stem to guide clearance and motor failure. The warranty company evaluates the risks and would rather pay $2k to fix the heads than pay $20k for a new motor.

- Any good engine builder, upon finding worn guides and beat up valves in a high revving motor will automatically replace them. Why do you think this is? Because they know that there is a direct causal relationship between nonconcentric guides, side loading/overheating of valves and then valve heads snapping off and being injested...ie., catastrophic and complete engine failure, all compounded by a high revving motor and valve train.

Any good mechanic knows and understands this. But if you have never worked on a motor then you probably don't. This is not a knock on guys that don't/can't work on their own cars. My best friend is far smarter than me, but he has never turned a wrench in his entire life. Says nothing about his intelligence. If I needed heart surgery, I would call him. But he is smart enough to know that because he doesn't wrench his car and has no idea how internal combustion motors work that he should likely rely on another trusted, expert source for information. This doesn't mean he blindly does whatever he is told, but it does mean that at some point he needs to accept/trust the available evidence as given to him by experienced individuals and experts in the field. Or he needs to start turning wrenches himself. Or he can just bury his head in the sand and pretend none of it exists and demand data that he knows doesn't exist (what we see here).

Over and over the primary advice is to CHECK and to LOOK. The procedure is simple and straightforward and free. And if you aren't capable then it can be done relatively cheaply. Apparently even this is too hard to understand.

dmuellenberg

Obviously you don't understand the impact excessively worn guides have on a valve. Yes, the LS7 may be tolerant to some degree of worn guides, but that doesn't mean that a valve won't fail because of worn guides. The more worn a guide is, the greater the chance that the valve will fail. I don't see why that is so hard to understand, pretty basic principle here. What kind of proof do you need that a worn guide can (and most likely be the cause of) a dropped valve?

I'll go back to my tire analogy. So every tire that fails has 0 tire pressure. Does that mean you should rule out low tire pressure as a reason for tire failure? Just use a little common sense.

SocalChvy

Oh wait, according to you I don't own a Z06 because I took up a different viewpoint.

😂😂👋

MTPZ06

Did you just change your name...or did you go through with the full Bruce/Caitlyn transition package? Don't worry...you're still good ol' Datroll to me.

Dan_the_C5_Man

Mordeth hit on something (several relevant points of course) that I will repeat and rephrase slightly.

Sports cars that costs between $60k and $120k (my car was $98k MSRP) have a natural tendency to be purchased by above-average earners. Think about that for a moment - how many auto-shop mechanics (not an owner, an employee) have the discretionary income to spend 60 to 120 thousand dollars on a non-necessary 2 seater luxury vehicle? Answer, not many.

instead, most Corvettes (statistically speaking) are purchased by 55-plus year old males (the latest stats suggest the median age for a Corvette owner is 61), who by the very nature of the wealth and status they've achieved have probably never changed their own oil, or if they did in thier youth they now take pride in the statement "I pay someone else to do that for me now..".

As Mordeth stated, the average Corvette owner is typically highly skilled (and paid) in a discipline not related to low-level automotive mechanics.

And that's a good thing in a way, as all those professional mechance have to eat and care for their families. The trouble comes when experts in other fields chime in to "add value" to discussions they have little to no practical knowledge in.

There is a reason that the ls1tech forum offers much more technical information about Chevy engines in general than the CF does - the majority of those owners drive Camaros and Trans-Ams and GTOs - they don't drive Corvettes. They can't afford a Corvette. They have to learn how to work on these engines to do cam swaps, head swaps, install headers, replace transmissions, rebuild differentials, whatever. They have more practical knowledge because it's a means to an end - they can't get from A to B without that knowledge, because they can't afford to simply drop off their car and write a $20,000 check, show up 3 weeks later with a completed build.

This gap between money and experience will always be a problem on this forum. You'll notice as time goes on, as the cars age (the C5 generation is a good example, and the C6 is starting to falli into this category as well) and become more affordable, less wealthy / younger buyers purchase them, buyers that fit more of the Camaro and Trans-Am profile I mentioned. As these more mechanically inclined people take owneship, that's when you begin to see the valuable input from a technical aspect on this forum (of course a small minority of folks exist that wrench and buy expensive sports cars, and we should all be thankful they take the time to post here).

It is what it is..

Allthrottleandsomebottle

Closed as requested........