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Let's get to the bottom line. How can you definitely tell if you have a valve guide problem. Other than hearing a ticking noise which could be from another source is there a way to check for this? I'm looking for a test that may be something like taking off the valve spring retainer and spring and checking play between the stem and guide.
Ticking is one of the indicators there is a problem. Another pull all the spark plugs and check for oil around the the threads. If the valve is moving beyond specs. the valve stem seal will leak oil past it and show up on the plug threads. You really need to check all the plugs as some may not show the problem. But the sure test is take it someone and check the valve movement with a dial indicator or similar tool.

PS Mine is an early production date 2008 with 19K miles. Had the valve guides checked today and they are all within tolerance. So not all are bad as some are trying to say on the other forum. But for peace of mind, I recommended checking them.
 

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Hi guys, I just dropped my 2008 Z06 off at a dealership here in Phoenix for this issue (I think.) The sound started abruptly last Tuesday and the car got promptly garaged. I finally got a chance to take it in this morning and the dealership pretty much went straight to the valve train. When I came back to grab my garage remote, the mechanics had the left valve cover off of the engine and had pulled the number 6 rockers off. The service advisor guy told me that they would more-than-likely pull and rebuild both heads and possibly change the camshaft. I bought the car used and bone stock, with 9800 miles on it and it had approximately 18,400 miles on it when this problem manifested. The only modification to the vehicle is a Calloway Honker CAI. To make this reply relevant to the thread's title, I have to say that so far at least, the dealership seems to be working with me and I'll report back on the outcome. Hopefully everything goes smoothly and no warranty or other issues develop.
 

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The only modification to the vehicle is a Calloway Honker CAI. To make this reply relevant to the thread's title, I have to say that so far at least, the dealership seems to be working with me and I'll report back on the outcome. Hopefully everything goes smoothly and no warranty or other issues develop.
Please keep us posted. With only a Honker intake you should be okay regarding warranty issues. If you have any problems, please do not hesitate to PM me.
 

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Well, I got the vehicle back today. No surprises. They ended up changing the cam, all the lifters and associated seals/gaskets. Other than trying to talk me into purchasing an $800 - 50K mileage service package, there was nothing too uncomfortable about the entire experience.

Below is the labor description:

Customer states there's a loud knocking noise when on. Found abnormal ticking from engine on right side at camshaft speed. Found to be more towards the rear two cylinders on right bank. Removed right valve cover for inspection. backed off cylinder #8 rocker arms and removed pushrods. Ran engine found noise still present. Reinstalled and removed cylinder #6 rocker arms and pushrods. Ran engine found noise to be gone. Removed right cylinder head for inspection of camshaft lobes and lifters. Found cylinder #6 intake lifter roller pitted and camshaft lobe damaged. Replaced camshaft assembly and lifters to correct. Replaced all needed seals, gaskets and bolts. Recharged AC to 1.10lbs, filled and bled cooling system and bled brakes. Set toe and centered steering wheel. Road tested 5 miles OK.
I did see/touch the camshaft and #6 lifter. The lifter surface was quite pitted while the cam had minor wear and looked like any damage was just starting. Hopefully this info can be helpful to others experiencing the same thing in their C6 Z06.
 

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Well, I got the vehicle back today. No surprises. They ended up changing the cam, all the lifters and associated seals/gaskets. Other than trying to talk me into purchasing an $800 - 50K mileage service package, there was nothing too uncomfortable about the entire experience.

Below is the labor description:



I did see/touch the camshaft and #6 lifter. The lifter surface was quite pitted while the cam had minor wear and looked like any damage was just starting. Hopefully this info can be helpful to others experiencing the same thing in their C6 Z06.
Thanks for taking the time to post the info. Glad it seemed to turn out
well for you !
 

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"9 z06, 6003 miles stock, idling in parking lot and motor makes a big boom, blue smoke, and now it won't even turn over. It blew up the hard plastic air cleaner housing. I suspect it dropped an intake valve and on the firing stroke the cylinder igniting went back thru the intake since the valve was gone and blew up the intake. This sucks
 

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Scott,

PM sent. Nor worries brother, it will get fixed. Just one step at a time.
 

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"9 z06, 6003 miles stock, idling in parking lot and motor makes a big boom, blue smoke, and now it won't even turn over. It blew up the hard plastic air cleaner housing. I suspect it dropped an intake valve and on the firing stroke the cylinder igniting went back thru the intake since the valve was gone and blew up the intake. This sucks
Scott, you definitely need to get GM involved. Depending on your build date, you should still be covered under the 5yr/100,000 mile warranty. My 09 ZO6 just had new heads put on due to valve guide issues. Fortunately, (or maybe not) it didn't take the block out.

Good luck man and push the issue with GM assistance if necessary. :usa:
 

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As posted by Mark200X late in June 2013 on the CF forum, the following was released by GM: ***edited***


Please do not post links to threads on other sites that have advertising/links to vendors who are not supporting vendors of this site


After having the guides go on my pure stock 09 ZO6 w/26K, I traded up to a '13 427 60th anniversary convertible. Does this bulletin suggest that the valve guide issue was not resolved in 2011 models and still continues thru the 2013 LS7 engines? That's encouraging to know they did not address the issue a couple of years ago and continued to let bad heads slip onto these otherwise great engines.
 

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I did a Google search for TSBs on the C6Z06, after dropping my car off at the dealer to troubleshoot a problem, and was brought back to this forum. Now I am getting a sick feeling.

I sure hope that I am not going to be one of the GM screwed. I bought my 2008 C6Z preowned with 7950 miles in 2010 from a Certified GM dealer. I met the prior owner and still talk to him (He had to sell due to loss of fight with his wife), and I truely believe that he was completely anal about caring for this car. It did not have a blemish on it. Due to fear of voiding the warranty, I kept it completely and absolutely stock, which was hard as in the past I tended to modify everything I owned. At 9000 miles, both cats clogged and had to be replaced under warranty for reasons unknown (gas alcohol content?), but it has been fine since. I have never tracked the car (not even a 1/4 mile test & tune night blast). Other than a brief run through the gears, and hanging an on-ramp at a conservative 0.9 Gs (very infrequent), I baby the thing. I have not had a ticket since 1979.

Today at 33,400 miles, while going to work I noted a ticking that soon became random clatter/rattling under the passenger valvetrain area. I had personally built a couple of engines in the past (i.e. 7000 rpm Pontiac 445 SD with BME aluminun rods, forged pistons, etc), so I know this C6Z sound is not good. I called the dealer for an appointment, and I weighed the risk of having the car towed (damaged by nimrod) and leaving work early to limp to the dealer to drop it off. No check engine light or misfires, but very noticilbe rattle/clacking. I essentially idled the car with the hazard flashers on for 15 miles to the dealer by using gears much higher than normal (i.e. 6th gear at 42mph) and left it. It is quite embarrassing to drive a supercar in a "hurt" and wounded manner. Thank God that a Nissan GTR or Porsche was not around.

Then I see this post, and would agree that if GM has identified valve guide problems, due to their loss of quality control, that there should have been recalls. The onus should NOT be on the owner to eventually discover and experience their lack of quality control, that they had already identified as occuring in frequent occurences, warranty or NOT. Catastrophic engine failure can be flat dangerous to life and limb in many daily driving situations.

My wife picks me up from the dealer, and I tell her this may not be cheap. I said that it had to be addressed ASAP, as it could blow a $14,000 engine. She responds that it would be ridiculous to drive a car only 33,000 miles and have the engine fall apart. I shrugged.

Wish me luck guys, as problems like this cause people to switch brands with extreme prejudice.
 

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Good luck. :sad: I assume you don't have an extended warranty?

At this point, I wouldn't buy a C6Z without having a heads & valve job done, especially as these cars get up in age. Expensive, yes...but it seems to be necessary based on the number of reported failures, at least for the peace of mind.
 

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As long as the engine didnt blow, then youre all good. :) Like Vant said, hopefully you have a warranty of some sort.
 

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Local Wallace Chevy dealer in Stuart did not give me a warm fuzzy. They said it was not valve guides or tank pickup tube or obvious upper valve train damage, but said they needed $700 for just disassembly of both heads to see if it was a lifter for sure. I asked if they had agreed that the noise was on passenger side and thought it was a bad lifter, why they needed to pull both heads. After a couple of phone calls and failed attempts to talk to mechanic, I told them to put car back together (valve covers) and I would pay them the $114 incomplete diagnostic fee and take it south to Palm beach to a Schumacker Chevy dealer who has more specialty on Corvettes. Stuart guy was pissed off, but I just wasn't getting any answers, ... just open-ended scope.

Oh and when I asked for the mechanics experience, I was told that he had done some engine work on 4 other LS7s. Not high level of experience in my book.
 

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Good move. :thumb: Any time you don't have a warm and fuzzy feeling about what is going on, time to move on.
 

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Good call. "well it could be the lifter, but well dissasemble the whole endgine just to make sure"......lol Any plans on modding it? or just keeping it 100% stock?

Kind of interested to see if theres valve wear..
 

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Wow- sorry to hear about your troubles, but honestly, if you were able to drive that far after the troubles arose, and there was no oil and water (together) leaking from your car when you arrived, it probably isn't going to be the type of catastrophic failure that you think it is. Good luck, keep us posted.
 

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OK, here is the story from Schumacher Chevrolet. A lifter on the passenger side rotated in its bore taking out the camshaft lobe. Cost to replace all lifters and cam will be just shy of $5000, but I am told that GM will cover $1700 of it on a semi-warranty claim, due to the low mileage. To top it off, I am told that the engine must be dropped out of the bottom of the car to change the camshaft. I always assumed that pulling the radiator would permit this task to be done.

Now I will need to display some my prior ignorance on the internals of the LS7, even though I have buillt a few Pontiacs in the past (i.e. BME aluminum rod 30-over 455 SD motor), and minor work on later Chevies.

All LS engines (including my Silverado SS LQ9 truck engine) use "lifter trays", which are molded to have flat and radius'd sides to hold the roller lifters in proper alignment with the cam lobe. I had assumed that my roller lifters came assembled in pairs with connecting/pinned plates between them, such that roller lifter rotation would not be possible.

On my LS7, this tray failed to keep the lifter in alignment. However, the shop foreman says that all of the trays are intact (not cracked or worn). After reviewing photos I could not find any credible way this could happen without breaking the trays (i.e. severe valve float causing lifters to come out is not possible, as there is a roof on the tray, where the pushrod comes through). When I inquired further how the lifter could rotate without the tray failing, I was told that the failure mode is the lifter rollers were not properly "hardened", which caused the roller to fail and then exert excess rotational forces on the lifter until it turned within the tray. He said the shop foreman had noted this in a couple of other "Corvettes", but did not specify which models. I noted that my LQ9 truck engine has the same basic configuration, but has 155,000 miles on it. The only differences are spring pressures and maximimum rpms. And the weird thing is that the car never threw a check engine light or demonstrated a misfire.

So my questions to the collective knowledge of the forum group is:
(1) Have you ever heard of a problem with improperly hardenened lifter rollers?

Considering this, I have asked the tech rep to attempt to pursue for a bigger portion of GM support, although I guess I have no choice.
 
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