NoOne

I'm getting closer to making my purchase but the more I read on the LS7 valve issues one question I could not find the answer to.

If I have the valve train redone, does that fix the problem, or does it just reset the clock on reliability?

I will be driving the cars at HPDE's and drive pretty aggressively. I've read about the issues with oil temp and all the rest.

I'm looking at an 08, buy it, get the valves/heads redone, is that a long term fix or just a short term bandaid and that has to be looked at again?

0Anthony @ LGMotorsports

They all seem to have wear but the early cars do not seem to show the same signs as quickly as the newer cars....for what it's worth.

Going back to 2005 when we first started doing these cars and all of the first 80-125 cars had head work done with upgraded guides and valves....every car is still running just fine.

tim414

Yes, it does seem to be a fix. Nothing has been reported after doing guides/valves. GM openly stated it was guides from their supplier.

Most are either buying new set of heads and selling the factory heads or sending factory heads out and then re-installing.

Add: The '08 should have the sump upgraded for track duty....on certain turns, it could cx oil starvation. Maybe look at oil cooler too.

Vette @ 71

Anthony, could you clarify the points you are making here. Little confusing .

What is meant by early cars not seeing the same signs and what model years are you referring to in the first 80-125 cars?

TIA

tim414

I take it to mean that after the heads have been done (guides.valves) they have not seen any issue. They started beefing these cars back when they were first out.

Vette @ 71

Got that part of his post!

tim414

The first part of his post means that '06/'07 did not show signs/failure as soon as the later model years as well. The newer ones seem to show signs early on it seems.

jedblanks

I think owners of newer ones are more aware of the issue and looking for problems earlier.

Every car I've checked has been over the service limit, but none were severe enough to be in immediate danger of dropping a valve, just headed that way.

0Anthony @ LGMotorsports

Of the cars we have seen break....

Almost no '06 or '07 cars have broken....at least that we have seen. The newer 09, 10, 11...seem to show wear much quicker than the older cars.

Going back to when we started modifying the cars....all of the cars that we did with upgraded cams, received new guides, exhaust valves, and one piece Ti intake valves. None of these cars have shown any signs of increased wear or have broken any valve train related components that we know of.

tim414

I was going to say that....but I highly agree.

LT5 John

Anthony, what about 2008 cars??...Do they fall into the older or newer ?

Gary2KC5

I know of at least four 06's that I've seen in person. two of them were my 06. 1st one when on the highway cruising in 6th gear on a trip @ 4K miles, the next was on the track accelerating from 3rd gear.

I thought the issue was identified and roller rockers solved the issues (note: I didn't read all the 2,200 posts in the thread)

Hib Halverson

Excerpt of an article about the history of the LS7 engine, soon to be posted at http://www.corvetteactioncenter.com
(used with permission)


Oops...In Spite of Best Laid Plans
In any car company's manufacturing process, a weak link can be parts suppliers. It can have the world's best, incredibly powerful, most durable engine design, but all it takes to screw it up is one supplier's quality control to slip. Worse yet: if it's problems downstream in a supply chain–say the quality control of a source of materials (such as a bearing maker) to a manufacturer which supplies parts (such as roller rocker arms) to a final assembly facility (such as GM's Performance Build Center)–the result can be quite unfortunate. Sadly, this has happened twice in the LS7s life.

The first problem developed in a relatively small number of LS7s assembled during the first half of 2007. In late 2006, about 1500 rocker arms were manufactured by GM's rocker arm supplier using defective needle bearing assemblies made by that supplier's source for bearings. The end caps of these defective bearings could fracture at the radius between the side and the top of the cap. When that happened, the top, or pieces of the top, separate from the rocker arm. Once the cap fails, bearing needles exit the rocker. The cap or cap fragments and/or needles would either lodge in cavities in the top of the head or be flushed through the oil return holes in the head and down into the oil pan. The oil pickup screen is too fine for the needles to get sucked into the oil pump, so the needles would reside in the oil pan until the next time the oil pan drain plug was removed.

In some cases, the problem can be worse than just needles in the drain oil. If a full "bearing load" of 33 needles gets loose, tremendous play develops between the rocker fulcrum and the rocker body with engine operation quite noisy. If the engine runs for an extended period with such a large large amount of play in the rocker arm, damage to the valve, the valve locks, the retainer or all three may occur. Damage to those parts may allow a valve to drop into the cylinder. The result of that is usually catastrophic failure of the engine.

A small amount of LS7s, assembled between early January and late July 2007, were built with these defective rockers. Most of these engines have been repaired under warranty, but even today, there are occasional reports of '07 LS7s with needles in their drain oil. With '07s out of warranty, repair of an LS7 with failed rockers will come out of the owner's pocket. If you find rocker roller needles in drain oil, immediately inspect all 16 rocker arms and make repairs as necessary because, if you don't address that problem immediately, dealing with it later may end-up costing you far more.

The second anomaly was excessive valve guide wear and was a problem with a few 2008 to early-2011 engines. The problem manifests itself as rapid guide wear with excessive engine noise and it's usually combined with high oil consumption. If the problem is not addressed when it's first discovered, it can result in engine failure.

According to statements made by Corvette engineers at the "Corvettes at Carlisle" event in the summer of 2012 and to web sites by Chevrolet Customer Service in the fall of 2012, GM found the condition during an investigation into a high number of warranty claims involving cylinder heads. The volume of problems with heads spiked from practically zero to a high of 6.5 problems per 1000 engines. Checking of heads which came back after warranty replacements found improperly machined valve guides. This quality problem was solved in February of 2011 and the solution has been verified since then with valve guide inspection of 100% of cylinder head production.

In mid-January, 2013, GM issued a "technical service bulletin" to dealers which said that GM’s warranty numbers for LS7 valve and head replacement, “...are very low with no indication of an excessive wear issue.” Admittedly, that statement seems to conflict with anecdotal information posted to various Corvette forum web sites along with what Chevrolet Customer Service stated in the Fall of 2012, however, the bulletin goes on to instruct dealers that, if a customer has a documented problem with LS7 valve guide wear and the warranty on his or her Z06 is still in force, it should be repaired at GM's expense.

We asked GM to elaborate on the information dispensed at Carlisle and by Chevy Customer Service, but it declined to comment and referred us back to the Customer Service statements made to the Corvette Action Center and other forum sites. Sources in the aftermarket engine service field have told us that, based on their inspections of a few LS7 heads from engines with high oil consumption, excessive valve guide wear and "improperly machined valve guides", revealed that the centerline of the valve guides were not concentric with the center line of the valve seats and that with a smaller amount of heads, the centerline of the guides were not perpendicular with the plane of the 45° valve seat. Either of these characteristics would cause high oil consumption, engine noise and eventual engine damage.

It is unknown how many cylinder heads have this problem but we suspect it is a small number.

Our advice: if your LS7 has a high level of valve noise along with what you feel is high oil consumption, take immediate action. If your engine is still under warranty, take the car to your Chevrolet dealer and explain your concerns. If the dealer can confirm the problem, it's likely GM will repair the engine, however, the above mentioned service bulletin, also, implies that if your engine is modified, GM will likely not accept a warranty claim, no matter how severe the valve guide wear might be.

If your engine is out of warranty, take it to a Chevy dealer for assessment of the problem but any repairs will be at your expense. If you're a DIY or you are having an independent service facility assess your engine's*condition, the procedure with which one can measure valve guide wear and how to repair the problem is covered in the "Engine-Mechanical" section of the Factory Service Manual.

'06 Quicksilver Z06

I remember your initial comments on this back in an earlier thread.

http://forums.corvetteforum.com/c6-z...post1582632612



Those of us who have researched this matter and followed it since it was initially described, will know of several comments from vendors, and the experiences of several other track enthusiasts who have had this done.

One of the more recent ones came from Charlie@RPM and I think hits home for what you are asking.

http://forums.corvetteforum.com/c6-z...post1583215120

http://forums.corvetteforum.com/c6-z...post1583441728

http://forums.corvetteforum.com/c6-z...post1582062835

Bottom line though as you already know, more maintenance is going to be required on any car which sees a lot of track time.

That said, whether it is or is not a "fix" is going to depend upon you definition of what "fixed" means to you.

"Fixed" to me doesn't mean that you can put 100K track miles on it and not have it fail.

But it does mean that I don't have to worry about it failing on the street, or failing should I throw a tune, or a few bolt on mods, or even internal engine mods at it . Nor do I have to worry that it will fail in any of the handful of track events that I do.

That's about as "fixed" as I can reasonably expect.

NoOne

Fix means to me not having a complete failure not traceable to an event.

For driving 7/10's at a track event the LSx motors last a LONG time. I talk to a lot of people who run NASA and such and they get less time ot of them but thats 10/10's running in crowds which is totally different from HPDE where you have more control over revs and shift points.

The general number I hear is a stock LSx, minus the Ls6 is good for about 200 hours of hard racing time at the amateur level. It's going to be at least 1.5 to 2X that number for HPDE if you take care of the car. That is a lot of track time. In a given day your probably driving hard 2 hours max.

So if there is a engine problem at 200 hours thats to be expected and it can be traced back to something, in this case time and hard running.

A completely random failure for no traceable reason is a problem.

Completely random valve train failure is a problem. If its a component them replacing the component should fix the problem. What really concerns me is the randomness of the failure.

Corvette wheel bearings are not made to hold up to track abuse but you know your going to get X amount of time out of them before you have problems/failure. Thats totally different than saying you put on a new bearing and it may fail in 1000 miles or 40,000 miles.

For those who do not think GM does now know what the problem is, they do. In the grand scheme its cheaper to continue to build failure prone 427's and fix the ones that fail than to fix it until the next iteration of the motor comes out, especially if it involves a change to the casting.

2k Cobra

Sooo... Chevrolet makes defective heads and we must pay to fix it!

Another question. Why would you want "Chevrolet" to "Fix it" when they don't stand behind their products?

philpacs

Then they are the majority of LS7 who don't blow, even some tracked ones, although I don't know exact numbers of course. I do know an instruction with compteley stock engine who tracks at that level and said he's done over 100 HPDE's without problem. Another from a previous thread said he's done around 12 track days a season since 2006 without issue. The engine seems stout enough for HPDE especially if you do that fix, since nobody knows if you'll be one of the unlucky like myself to pop a motor. Although I'd still do preventative work to check like I would any street car that is tracked this also includes slowly doing brake, cooling, oil upgrades, suspension as your skill and car improves but this again for any street car on the track. After spending much time at the track I haven't seen any signifcantly run street car on the track without upgrades/fixes excpet for maybe GT3's but even those guys are changing pads/tires etc.

'06 Quicksilver Z06

Initially you lost me in the first sentence with the double negatives,

But as I read more of your post, it I see and understand your point.

2k Cobra

On NoOne's reply.

My neighbor has a Duramax.

Had an engine related part fail. Replaced repaired under warranty.

Same part failed again. Replaced repaired under warranty.

Same part failed again. Sorry, your warranty has expired, but we will give you a discount to replace repair the same part.

He mentioned selling it.

JoesC5

From what I've read on this forum, valves drop without any warning.

people that have noisy engines do not always drop valves and people with quiet engines do sometimes drop valves.

GM is passing the buck to the customer of their product to determine if he has a problem and what should be done to fix the problem.