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GM response to failing LS7 engines

164K views 97 replies 40 participants last post by  TacoSauced 
#1 · (Edited by Moderator)
Hello all,

LS7 Valve guide issue summary:
• Affects a small, number of '08, 09 ’10 and ’11 Z06’s
• GM discovered the condition through our cylinder head warranty data involving a very small percentage of our vehicles.
• Through inspection of returned heads, it was determined that a machining error in the valve guide had occurred at our head supplier.
• The quality issue has been contained as of Feb 2011 with 100% inspection of all heads.
• The most common customer complaint has been excessive valve train noise.

However if the condition is not addressed, it could result in engine failure. To date, where this condition has been observed, it has occurred early in the vehicle life.

What customers need to know: They should drive and enjoy their vehicles without fear. If their car demonstrates this condition, they are likely to hear unusual valvetrain noise first. If you have a concern regarding this issue on your personal vehicle feel free to contact me through private message on this forum and we will work to assist in resolving your concern. Feel free to contact me through Socialmedia@gm.com please put attention Evan in the subject. As always, vehicles that have modifications to the powertrain or the calibrations, are no longer covered by GM's warranty.

Sincerely,
Evan, Chevrolet Customer Service
 
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#46 · (Edited)
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.
 
#47 ·
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 !
 
#48 ·
"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
 
#50 ·
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:
 
#51 · (Edited by Moderator)
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.
 
#52 · (Edited)
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.
 
#64 ·
I Corner, you are correct - the motor does NOT have to be dropped. I visited my car at the dealership almost every day that they had it, just to check up on it. They did pull out everything in front of the motor but they had the entire top end off with the motor still in the car. I suspect that either your dealer is trying to milk you or the mechanic doesn't know how to work on Vettes. Best of luck.
 
#53 ·
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.
 
#62 ·
No extended warranty. A friend of mine has an 03 Z51 with extended warranty and ended up paying 100% to correct a differential problem. Challenge was that warranty would not pay claim until the problem was properly identified and the dealer would not fully identify the problem until the thing was dissassembled, so it was a Catch-22 situation. He ended up going to another shop and paying the lower price just to repair it.

I guess I assumed that if I took care of it and did not beat the thing up, that it would last 100,000 miles at least, like all of my other cars.
 
#56 ·
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.
 
#58 ·
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..
 
#59 ·
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.
 
#63 ·
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.[/QUOTE

I guess it was worse than I had hoped, but better than I feared. Looks like you have a very nice stable. If your Z has a problem, just drive the GTR. How is your GTR holding up? I met a gent in Palm Beach who slightly modded a 2009 and when its transmission broke, Nissan denied all warranties. Fortunately, the bum is stinking wealthy and modded the thing for another $80K to be both a low 9-sec quarter mile car combined with a decent road racing suspension.
 
#60 · (Edited)
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.
 
#66 ·
OK, the final cost to me was $3133, which was after GM covered $1740 of the repairs. However, this included some routine service, which I authorized to replace fluids/flush (transaxle, differential, brake, clutch, coolant) and also to do a top engine clean. Of course since most of these systems were breached during the engine disassembly and to "drop" the engine cradle out of ther car, it seems like they reduced the cost for some of the double dipping type of work (i.e. would have to flush brake lines anyway after disconnecting lines).

I did a close inspection of the engine compartment with a flashlight from above, and noted that the power-steering cooler fins were bent all to hell. I agreed that it was cosmetic damage. However, as the car is absolutely pristine except for 3 very small scratches, which are tough to find unless you know where to look, I insisted on replacing the cooler, as this would devalue the car on a casual inspection. They agreed, put it on on order, and promised to replace at no cost to me. Other than that I saw some small broken wire loom plastic pieces and a stud nut that did not appear to be bottomed out on the ABS mount, that they said was supposed to be that way. They said the work is warrantied for 12 months or 12,000 miles. However, I reminded them that if I have any problems associated with the work they did (i..e a leak in any system they breached, abnormal tire wear alignment), that I consider that part of the warranty work.

A friend of mine called a GM dealer in Ohio, that he says is renown for being Corvette experts, posing as me with the type of engine failure that I had. He said that he was told that this Ohio dealer would only expect $1000 from GM for assistance and estimated that my total costs woudl be about $4000. So I guess Schumacker treated me well in comparison. That Ohio dealer also said that they had only seen this failure twice and only on LS7 engines.

The car seemed to run fine on the way home. The car still has mild valvetrain noise, which I understand is just normal for this engine. However, now I wonder if the metal shavings that I saw on the magnetic drain plugs a long time ago was early wear on these lifters or "normal LS7 engine wear".

I had never taken this to the track before, but now wonder if I need to run the hell out of it to make sure that it will hold up.

Rick
 
#69 ·
Just had my 2007 Z06 exhaust valves tested (wiggle test) for valve guide wear. My exhaust play was .008"-.009" in all exhaust valves, twice the factory operating range. My car is bone stock with 10,000 miles and very minimal valvetrain noise. At least it's a great sales pitch to the wife who approved the purchase of my WCCH Stage 2 heads today!
 
#70 ·
Sweet.... now put a cam in there. Might as well since the heads are off.. and since the heads are off, put some headers in...

What made you go with WCCH
 
#77 ·
I would steer clear of dealership in general. Track record shows that their techs arent as knowledgeable about the LS7s. If it was me I would have a reputable performance shop do it. Reason why I say that is bc some of them might apply that cost towards getting the heads fixed. Being that youre in warranty, you really have no option but to go to the dealership. Just make sure their tech is very VERY knowledgeable about the Z
 
#79 ·
Just wanted to report back... I picked up the Z yesterday from Synergy Motorsports after they installed WCCH Stage 2 heads, Callaway Honker and Dyno tune. My mind is at ease with all valve issues taken care of. The car runs smooth as silk now and makes 493.3 hp to the tires, not bad for stock cam, maifolds and cats. Rick did a great job on the install and tune! If you live in NorCal and own an C6 Z06, I highly recommend doing this mod... great peace of mind and incredible performance gain.
 
#85 ·
GM is a little late....5 or 6 years...and a little short on their responsibility. Their dealings with the Z06 valve issue cost them a new truck for me and a new car for my wife.
Mine is fixed without their BS help. I'm sure I will not be dealing with GM quality again.....just someone else's sorry quality.
 
#86 ·
I noticed this in another thread...

Posted By lebvette
Re: How Much Horsepower are you making?

551/501 Stage 4 Stalker from Ragin Racin and the goodies that go good with it.
I see you've done some aftermarket engine work on your Z. Did you have valve issues yourself?

Mike
 
#89 ·
Response to Grinder. I do not think you could have hurt a stock or near stock LS7 valvetrain from a missed shift, unless you were at max rpm in one gear than then mistakenly hit the gear below it. I believe the stock rev limiter is 7100 rpm on a 7000 rpm rated engine. If you set it to 6800 rpm, that would be conservative. Compression test would confirm status, unless you had a hurt lifter that is not keeping up. I would think you would hear a collapsed lifter or worn cam lobe as upper valvetrain knock or clacking.

I bought my car with about 8000 miles and 2 1/4 years on it. With the original crap Goodyears, I hit the rev limiter a few times as they would spin to redline almost immediately with traction control ON on dry pavement.
 
#92 ·
If you have a 3/36 warranty from a good insurer don't bother with heads. If it goes, you get a new motor for the deductible.

I bought my car new in '13 and put a GM warranty on it that expired last year. I wanted to have some minor porting done to my heads and just got them back. As long as the heads were off I put in new Ferrea solid stainless steel exhaust valves, new springs, guides, trunion upgrade, valve job and bowl blend. The machine shop charged me right at $2,000.00. I still had to pay labor, gaskets, ARP head bolt kit, de-carbonizing the pistons, new fluids etc was another $1,400.00.

I didn't need to do this, but was messing with the heads anyway so why not just do it all while there. And now that all that work is done I am having to get the ECU re-tuned because the car is running a little rich, about 6-8% so far as we can tell. Until I get the valves to seat I can't get a WOT data run to send to my tuner . So you can throw in another $250.00 for the re-tune. So all done if you tear into your heads plan on spending about $4K. Hope that helps you make your decision.
 
#93 ·
Just joined and this is my first post. Reason being...purchased an '06 Z about two weeks ago. It's got 21K original miles. In reading some other forum comments over the last few weeks, I saw mention of an issue with the heads. After reading the majority of posts and seeing that many are reporting (sometimes serious) issues with their low miles LS7s, I'm wondering what my best course of action should be.

Not only it's got only 21K miles, whomever owned it prior treated it with the height of respect. In every way, the exterior looks virtually new. I haven't found a scratch or blemish of any kind anywhere on the body, including the front facia (no rock chips). It doesn't look like it's ever once been driven in the rain, as many areas of the undercarriage are exceedingly clean. Point being, I intend to continue respecting and caring for it at the same level it has been.

I think I probably know the answer, but am posting since this thread started 8 years ago and maybe things have evolved (for the better or worse) with GM's stance on the issue with time. While I've kept my ears perked over the years with all my cars, conscious of any abnormal or suboptimal engine noise, I'm not sure I would've noticed only the slightest ticking noise if I hadn't earlier read a comment about issues with the heads. In other words, I'm confident only the most keen minded mechanic would ever feel the motor isn't running perfect. But, I'll hear it on occasion at idle and low rpms.

And with others mentioning that Chevy V8s in general over the decades have been known to have a mild audible ticking, I'm torn between spending $X on a lifter guides QA check since the noise is far from prominent. On the other hand, I can reason that I've got an extremely healthy low miles LS7, and correcting the issue now will keep it healthy for a good 100K miles, obviously.

I also read the varied opinions on GM's attitude; what they should have done, what they have done, etc. One thing I agree with is that there should've been a recall. No major head-scratcher to many who know the only reason they didn't, was their full understanding that it would've killed them financially...to correct an internal engine flaw in the whole fleet. But I can also easily reason that for the original owners, who paid about $70K for their car, specifically because they were led to believe with all the LS7s' fanfare, they were buying an exceptional motor ("hand built", long list of special parts and technology) as part of the justification for laying down the big bucks. I myself believed just that when considering the purchase.

I live in the Colorado Springs area and there are several Chevy/GM dealers in town. I suppose a call to them asking if they'll offer a valve guide health check at little or no cost, supported by the fact that my Z's mileage is so low. Sure it's now 14 years old, but would otherwise be well under the standard 36K miles warranty (or X years always got me, especially being such a relatively short timespan after new. It seems more logical to give a timeline like double of the average miles driven/year "Six years if under 36,000 miles"). Stating I've heard a ticking noise, armed with the mention of the many others on even just this thread alone might help.

I know...long winded, but that's me. I've owned six Turbo Regals (4 Grand Nationals and two TRs), and spent years on forums. Can't help it...just gotta keep flappin'. ;)
 
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