71HO454

Purchased the Z06 earlier this week. Velocity Yellow 2LZ one owner car and only 6700 original miles. My concern is if the heads were addressed and/or at least checked. I have spoken to the service manager at the "servicing dealership", but there isn't any mention in the records about the heads being checked. Their records seem very detailed with regards to oil changes, emissions tests, fluids, etc., etc. but that's it.

He claimed that he didn't see any TSB's regarding the heads and/or open recalls, in general. Was there is a TSB issued on this potential problem?

Am I at a dead end here?

Thanks in advance!

Pounder

http://www.americanheritageperformance.com/ talk to Kohle !!!

grcor

The dealership is clueless. You will have to assume nothing has been done. Here is a link to the TSB. https://www.corvetteforum.com/forums...n-from-gm.html

There are several issues with the LS7 heads, not just one. The 2 biggest issues are the firm Chevrolet used to machine the heads did a poor job at machining the valve guide and valve seat concentricity affecting all model years. As the valve opens and closes it rocks back and forth in the guide overstressing the valve stem leading to valve failure (this can happen to both the intake and exhaust valves). In addition the exhaust valves used from the start of production to May 2008 are subject to failure because of their poor quality. The hollow valve stem does not have a consistent wall thickness and the weight of these valves can very as much as 4 grams. After May 2008 Chevrolet started buying exhaust valves from Mahle which have a consistent thickness that is double the thickness of the previous valves. This is why 2006 - 2008 LS7 are more likely to drop exhaust valves.

The next issue is with the titanium intake valves. Titanium engine parts have to have a coating placed on them or they will wear very quickly. The manufacture put a chrome-nitride coating on intake valves, unfortunately this coating can have a rough finish which will wear the valve guide. The manufacture has an addition process that polishes the coating, but Chevrolet did NOT include this polishing process in the specification for the LS7 intake valves. This is why 2009 - 2013 LS7 are more likely to drop intake valves.

You need to do a wiggle test to see how much value guide wear you have. Do a search for information on how to do a "wiggle test".

71HO454

Excellent, thanks for the very detailed information.

itomh

I bought an 08Z this time last year and I know if frustrating trying to figure out if heads were done or not. At this point you should just assume that they were not unless you can find 100% proof. There are only a couple visual signs that can hint, I repeat, hint that heads were done. look for steering bracket notching or if the head bolts were swapped out for ARP head bolts. These are not guarantees that the heads were fixed. I wouldn't go wasting money on the wiggle test, cause that is just labor that could have been applied to your head fix. I'm glad you are aware of the head issue and recognize it as an issue that will keep you from enjoying your Z06. I looked for the signs and didn't find a single hint. However, I dug as far as I could with a flashlight and magnifying glass and noticed I had a small oil leak on the passengers head gasket, which made it easier for me just to pull the trigger on AHP heads. There's a nice write-up here on the forum that guided me through the process. If you are somewhat mechanically inclined you can do this. If you wanted headers, this is the perfect time to do this.

71HO454

Thanks for the great info!! I'm a computer geek, so I try to avoid twisting wrenches, but I have a very competent performance oriented mechanic who specializes in cylinder head work, along with CNC porting & flow bench services. I'm going to consult with him first, since he's local and I've done business with him for over 25 years on the drag racing side. I bet he can whip these heads into shape with all the best parts in heartbeat! If not, I'll surely send for a set from AHP.

Hahaha, headers you say?? My wife isn't going to like you!!

MTPZ06

You're on your own on this...GM is of no help and the TSB is a joke. "Is the Check Engine Light ON?" If it gets to that...its because there's a window in the side of the block. There is noting preventative about that TSB that keeps an owner from experiencing a catastrophic engine failure.

Wiggle test, and get the heads reworked if you don't like what you see. My '09 had 14/16 guides beyond GM service limits with only 15K street miles. I highly recommend AHP for their experience, knowledge, customer service, and their approach with utilizing unique materials in fixing the LS7 heads.

Tech

There are more threads on this than you could read in a week. Use the search function and get a big bottle of whatever you like to drink.

71HO454

Yeah, that's just how I want to spend my time.

Tech

Then you probably shouldn't read the Z06 part of the forum. New owners, like yourself, come here every week asking the same questions. We end up reading the same stuff every week.

keeso6z

Hopefully there is a reputable performance shop in your area that works on Corvettes and is aware of the problem with the LS7 heads/valves and can take care of you. I have a great shop in my area and they warned me and I only had 2,000 miles on my car. Got it done and they milled and ported the heads in addition to some other performance mods.

71HO454

All you have to do is read the thread title and if it mentions the cylinder head issue, go troll another post. How simple is that?

Tech

Sorry you didn't feel adequately coddled. I actually wasn't really busting your *****. If you have such fragile ego, the last little bit of information I'll ever give you.. is to stay off the internet. Enjoy your new timebomb.

71HO454

Fragile? Coming from the troll who complained that you might have to read something twice? Oh boy, life's a bitch!! Was my solution to your problem not simple enough?

One would expect a person with such a heightened level of awareness and a critical eye towards so called "fragility", to realize this blatant situational contradiction.. But, maybe not..

Ok, I got the info I needed, no thanks to you, of course!! I'll leave you to police the forums. It's time to make some money.

Many thanks to those who posted substantive answers in this thread. You saved me precious time.

El Paso Vette

I know that if the former owner had WCCH heads installed that there is a plate or etching on the heads that will confirm (or not) that the heads were reworked. You can see this easily under the fuel rail cover on one side.