erikszr1

I was a tech at Chevrolet for a few years, 2010-2014 the only ZO6 at our dealership getting new heads was my 08. Mine were super bad, I didn't even remove my rockers to see the play mine had. And the other techs were there for a lot longer than, by 5-10 years. None of them ever heard of it, or replaced and heads or guides in a vette. facts

EWK

Had my 2009 with 7,600 miles done last year by Katech, every intake and exhaust guide was out of spec. There was a significant change in valve train noise after the heads were reworked. Prior to the rework the valve train noise coming thru the AC vents sounded like a loud Japanese sewing machine, after the rework you can barely hear any valve train clatter. Huge difference.

Vette @ 71

It's unfortunate that valve train noise does not appear to be a symptom of guide wear. Several posters that had no significant sewing machine noise had guide wear beyond spec. Would be interesting to conduct a poll (yep another poll) to identify whether there is a relationship between valve noise and guide wear..?

SCCA VETTE

I have a theory on this,keep in mind it is just my theory!

Most Corvette owners only take their cars to the dealer when it is a warranty related issue. If the car is out of warranty most will find a reputably local tuner shop or a Corvette specific mechanic.

Most of the failures are happening out of the warranty of the cars due to time but not miles. These are not daily drivers (in most cases)so the miles are a fraction of the 36K mile warranty even 10 years later.

So what has happened is the problem did not show high warranty claims to GM because a majority of the cars did not fail under warranty forcing them to recognize the problem early on. After the problem was discovered a large majority of owners have fixed the problem prior to the valves dropping, now though these cars would have counted towards the % of failure needed for a recall, they are not going to now.

The data from most all the cars on the forum shows the guides are out of GM spec. Had these cars been driven like daily drivers and with some spirited driving (they are performance cars) thrown in those miles GM and the dealers would have had to recognize the problem and do something about it and the dealers would have seen a lot more of these coming in due to warranty still on the car. There is some of the larger high volume Corvette dealers that are aware of the issue. I also know that the district GM rep for my area is well aware of the problem to the point he mentioned these conversations on this forum when I discussed it with him. I got the same reply as others, $500 to tear it down and measure the guides and if they are out of spec GM agreed to replace the guides however I will be paying for R&R labor.

SCCA VETTE

I will help you out with this! Mine sounded like it was going to spit all the internal components out on cold start up. It was bad enough that until I was able to get it in to get the heads done (waiting list) I would let it sit and get to operating temp before driving.

When I get it back I will report if the noise has went away. I also have asked the shop doing the work to see how bad the guides were on the heads that come off it after 24K miles.

JoesC5

~25,000 Z06's divided by ~3,000 dealers, equals ~8 Z06's per dealership. Then subtract the number of Z06's that had their heads done by a non Chevy dealership and the average drops for the Chevy dealers. Then when the dealerships in areas with a high concentrations of Z06's see a greater number of Z06's than say a small dealership in Aurora, Missouri, chances are that the small dealership will have never seen a Z06 with a dropped valve(or even a Z06 in the shop for any reason).

Even my local dealership(a forum sponsor) that is #40 in annual Corvette sales, doesn't see that many C6 Z06's in their shop. Just not that many Z06's around here. I know of around a half dozen and only one has dropped a valve. It was a used Z06 with an aftermarket warranty(out of GM warranty). The owner didn't have a local Chevy dealer replace the engine with a crate LS7, but elected to have a local speed shop build a motor for him, thus the techs at my local dealership never heard of that particular Z06 having valve problems.

When I decided to install new heads on my 09 Z06 when the warranty ran out, I never considered having my local Chevy dealer do the installation. Of course, if I had dropped a valve during the first 5 years of my ownership, I would have had a Chevy dealer install a new engine under warranty.

Facts.

Nowanker

still not surprised about the dealer tech lack of awareness. When I was at the BMW dealer (a "performance" brand, right?), I was the only one out of 25+ guys that gave a rat's *ss about anything performance related. No one ever looked at any of the BMW forums to learn what was happening in the outside world. It was just a job...
got to punch out now.

dmuellenberg

No, that doesn't prove anything. Your point is that the wiggle test is useless without accurate measurements. In this case, what good does it do to know if they are at .040 or .080? All you need to know is that they are shot and need fixing. I agree that the wiggle test isn't good enough if the guides are marginally out of spec, but in the case where they are way out of spec the wiggle test is good enough.

Aguita

To the OP, i have a good friend that have a 09 that he bought with 5k miles last year, to his surprise he was told by another z06 member that knew his car (and was in the process of breaking-in a new motor) due the fact of a dropped valve, that my friend did a good buy bc his 09 have a brand new engine due to a dropped valve by previous owner, he contacted the previous owner and asked what happened... simple standing on a red light motor grenaded itself (never tracked and not abused).. I bought my 06 with 20k miles scared after reading all the issues with the valves, well i pulled the trigger bought the car and decided to invest $2k with labor on the heads,after sending my head back to AHP i got contacted and was told that all but 4 valves were wayyy out of spec and surprised the motor didnt blew, after that my friend decided to do the same and send his heads of his 4k miles motor...


So why dont you invest those $1,500 and forget about a $16k motor that can grenade itself?!

you can get away or not.. like walking on a mine field..

GL

z06clif

My tech is a friend who is the Corvette Tech at my Dealership. He has been the CorvetteGuy at that Dealership for 15 years and in that time he has never done a head job or even heard of one. Hes a GM master tech and works exclusively on Corvettes except in the winter when they are sleeping...Lol

Clif

NOrrTH

Thanks for all the information guys. I am going to get the heads done, I just need to find a good shop in BC to do it.

Aguita

Contact kohle @ AHP he have cores so you dont miss driving your car, pulling the heads its easy if you are mech inclined you diy

Bill Dearborn

No there isn't. If you could see their warranty repair records they probably saw very few failures due to valve guides or what ever else might be causing the valves to drop. They were absolutely right that not driving the cars leads to problems. If there is truly a valve guide issue the fact that close to 90% of the cars weren't driven enough to make a failure become obvious while the cars were under warranty definitely warps the info being sent back to the manufacturer. It gets it's feedback from repairs being done in it's franchised dealerships not from internet bulletin boards. An 09 is a 7 to 8 year old car that had its power train warranty expire 2 to 3 years ago. If a number of people had a problem while the cars were under warranty then maybe GM would have found out about them. Internet rumors aren't to be believed because they are just rumors and rumors are often out in left field as far as validity goes. As for having the valves drop on a 4K mile engine that isn't likely. I do know of some that dropped on engines that had 13K miles on them. Those engines were replaced under warranty just like my engine was replaced under warranty when it dropped a valve at 24K miles when it was close to four years old and had about 4K track miles on it. By the way most of the engines that dropped valves had a lot of track duty on them.

Wiggle test results with reports of loose guides are one thing actual failures are another thing. At this point in time which is almost 5 years since my car dropped a valve we still do not know why the exhaust valves (not intake valves) were dropping. As the dealer mechanics told you loose guides should show a lot of oil consumption and they have to be really loose to cause valve stem breakage. Most of the so called wiggle test results that showed excessive valve guide wear showed the guide clearances were only out by a few ten thousandths of an inch which wouldn't have been sufficient to drop a valve.

I wouldn't worry about your car dropping a valve until you add at least another 10K miles to it especially if you start to use it for what it was designed for Vs a show piece. The car is a sledgehammer on the track and about the only thing that beats it is a bigger sledge hammer which the C7 Z06 definitely is.

Bill

outhouse

Horse crap. With all due respect Bill.


Even Hibs 14 heads were out of spec brand new on the shelf.


Not only that the widdle test is far from accurate for anything other then telling if a guide is literally trashed.


If you can actually wiggle the valves by hand, they are far from a few ten thousandths of an inch out. This is a fact. It is not up for debate.









You are literally insulting the good members of this board and the valuable feedback were getting on this specific motor.




These are factually more then rumors. WE are dealing with factual failure not Chinese whispers here. We are dealing with factual measurements by credible and quality machine shops that show excessive guide wear.




In every hobby I am part of, the forums for said hobby hold the highest amount of collective knowledge on any given topic. It is no different here.





You are right it is not a conspiracy Bill.


Its outright lies and deception, from the top. It is typical when practicing law, Its called silence or you will be liable.


They produced bad heads and they know it. Don't kid yourself. But they have not nor will they EVER address an out of warranty failure beyond the local dealerships goodwill programs when a client is just a hair out of factory warranty.






THE BOTTOM LINE.


Is that loose guides do cause valves heads to pop off, the issue is that loose guides does not mean failure is instant, some can get damned lucky and drive for 100k with loose guides and not pop a valve.


But the danger of failure is there and the odds of failure increase with excessive guide wear.


So if you don't check your valves, and one pops, it is your own fault, and if your out of warranty GM sure as hell is not going to bail you out.

outhouse

I will not say its a bad idea on this car as obviously it could be good insurance for other possible failures besides valves. This is a personal decision you are solely responsible for making.




Spending 2g's having the heads redone for peace of mind seems to be the most reasonable and logical decision here.


They quoted me 11k as their cost for a 06 with 43k on the odometer at cost, just due to the company the dealership uses. So me? I'm rebuilding heads.



Protect your own butt. This means checking your valves to see how much wear you notice as the engine ages.









10k might not sound like much, but they are lucky to get 20-40 miles out of the high performance factory engines running world records. Its amazing this engine can go over a 100k at 505hp. So that's only 10 checks to stay ahead of the ball game here.


At 10k intervals it lets you track wear, because when they get a little loose at some point your going to want the heads yanked to get the accurate measurement as Hib describes. And or just rebuilt.

LFZ

Look noob. Bill has contributed more to this topic than anyone on here. He has experienced a blown motor and even had actual guide measurements (not a wiggle test) taken on his replacement motor. Bill also owned a Z and drove like how it was meant to be driven which is a lot more than can be said about yourself.

Looks like you're just another internet expert on here spewing crap just because you read a few posts by the usual suspects with their scare tactics....typical corvette forum.

Michael_D

Well unlike the vast majority of 'experts' on this subject here, I actually build engines. And that's not vicariously, through the efforts of others that they give money to.

There is a problem with these heads, and anyone saying different clearly has motive for saying it. What that is, I don't know, don't care.

Is the problem as wide spread as some of the drama queens want to make it out to be? No, not even close. Again, motive for running around claiming the sky is falling.

Be smart and proactive. Nothing wrong with the "wiggle test", other than its terminology. It is a great way to quickly (RE: Cheap) to screen for excessive guide clearance. Guys like me (older, experienced mechanic types) have been doing it for decades. Anyone saying it's a dumb thing to do, or who completely discount its value - has no experience. Either that or they have an agenda.

outhouse

You don't know me or the first thing about me. Leaves you assuming Noob

outhouse

Thank you.




I spent weeks reading on this issue,. and there is pattern of people who stick their head in the sand like a few above.


And a pattern of overblowing the issue.






Regardless, as you stated being smart and proactive, is the right thing to do.




Anything else is generally from those who were rich enough to buy into the hobby without the actual knowledge to do the work themselves. Then think they know what they are talking about.

outhouse

He, like you, insults this communities members, as you do.




Do you even have the intellect to know what a fallacy is? a red herring perhaps?




Your pathetic insults show you cannot refute a single sentence I wrote on the topic. So you went straight for childlike ego bruising.




Nice