ATC399

Sir you should duck and cover incommminnng...

BigVette427

I have a stock '12 Z06 and it takes probably 10+ miles before finally getting up to temp; it will sit in the garage at idle and not budge, while the water temp will eventually rise. Every startup I check the tire pressure to make sure they are all around the same, check again after I get rolling in case there was something lodged in one of the tires and I am still close enough to milk it back to my garage, and then change the DIC over to oil temp where as I don't go much over 2k until it gets up to around 150°.

The "fix" is in the concentricity of the valve guides. There are some other issues about the various combinations of a variety of parts, but the "problem" is that the guides were inconsistently machined and installed incorrectly. AHP's standard Package 4 LS7 head rebuild at $1,358 will take care of everything as far as the valve guide issue is concerned. No need to not buy an LS7 or worse yet, get rid of one, because of the valve guide issue.

Unreal

It is a lot like smoking cigarettes. My grandmother on my moms side lived to 98 and smoked 2 packs a day. Does that mean smoking is not an issue? Nope. Plenty of evidence otherwise. So people saying "I have 90k miles and no issues" great for you. Doesn't mean it is good advice to ignore it.

MyLS1Hauls

It has been the concentricity of the valve seats, that has been in question, along with too much initial stem to guide clearance. If those were the only causes, then heads that have been "fixed" would never prematurely wear out again, and that hasn't necessarily been the case.

Frankie2blue

It's so hard to tell on this issue because of all the different combinations of cams and other mods done to so many of these cars. Other cars are heavily tracked, so of course will show more wear.
The only baseline I am interested in seeing is a street driven "fixed" car that is left bone stock that has its heads rechecked after 20000 miles or so and see how the heads have faired. Now that to me, would be very interesting, but there appears to be so few cars that have been left stock that im beginning to think it's a stat I will never see. 3/4 of the folks I see fixing the heads are then dropping a cam and other changes in while they have it open. Makes it real tough to tell IMO.

nick14003

if you plan on keeping the car for life... you are going to have to change everything at some point in time... How can you say you wan't to keep it for life if you are considering trading it in already?

SGT_G

How much does the service usually cost to check heads at a dealership? I bought my z06, 100% stock down to the tires and air filter, a little more than 3 months ago and it had 18,000 miles on it. I'm now approaching 23,000 and I'd be interested in where my heads are sitting as of now. I also drive the living **** out of my car. In fact there are few days where I drive it mild. I've been to 176 mph, above triple digits many times, over a dozen drag races, many roll races as well as countless sprints through the gears. At this point I can't determine if anything is going awry with the motor but I'm not very concerned as I have a GMEPP warranty active. So at worst, I'm inconvenienced for a month or so.

DWRAT

Your stock tires made it to 18,000 miles?
Mine were to the cords on all 4 tires at 13,500.

Tech

GM does not use the wiggle test anymore to determine if the valve guides are out of spec. For a GM dealer to test it, they'll have to remove both heads, disassemble them and test them. Most people just choose to have them replaced if you are going through that much trouble.

Dan_the_C5_Man

IF it were only that simple..

A month, that sounds very conservative - ask around to the folks that are still here and experienced a blown motor.

Do you REALLY want GM techs climbing all over your car? Unless you live near the very small handful of trustworthy dealerships competent and qualified to replace an engine in an Z06 (without damaging anything or creating additional issues), I would think not.

Do you know about the bottom-end issues with non-lead main bearings and Ti rod scrubbing in the newer crate engines? Assuming your car is a pre-2012 model, do you really want the potential to introduce ANOTHER potential problem / failure point?

And we haven't even discussed the potential liability / additional damage of the engine failing at a race track or on the street (valve drops, hole in block, oil exits block and onto pavement / rear tires, car spins / potentially causes car(s) behind you to spin, etc.).

What about potential re-sale / value depreciation, "Z06 for sale, engine replaced.."?

And finally, replacing the engine with the same defective craftsmanship only buys you another XXX miles, it doesn't solve anything..

Warranty? Who cares... Check the heads and repair as needed, IF you really car about long-term ownership - for a lot of folks in here, it's "just a car", something to be used up and move on to the next - and that's o.k., but if you really love it and intend to keep it for the foreseeable future, that's a different approach.

Les

Or he could look at a much more current poll, now that we've learned a lot more about the problem-
https://www.corvetteforum.com/forums...-registry.html

SGT_G

Honestly it's probably a second set the previous owner bought that was the same brand as those from the factory.

SGT_G

​​​​​Your response is tailored to your own opinion. I personally don't care about GM techs fixing my car. I don't care about a replacement engine with the same quality and if any second or third order issues arise, again that's what a warranty is for. I don't care about resale. I drive the living sh*t out of my car and drive it in any weather which allows it. This is not some one of a kind collectible show car. It's a mass produced street legal race car that a fraction of the owners ever fully utilize. As for the heads, why would I spend the same or even more money on correcting one issue. You think the heads are the only problem a Z06 has ever had? So thanks for sharing your information/experience but I think I'll be better off with my method

SGT_G

That's good info. Sounds like I won't be getting that done without warranty work. Dealers in my city charge $130/hour

Dan_the_C5_Man

Of course it is.. Sounds like you are clearly in "Column A", and good for you, beat on it as long as the warranty is in effect. I would hope that if I see you on a race track, I am in front of you, as your warranty won't protect me from the oil slick.

Racingswh

Every single LS7 I have seen used at the track regularly has expired including mine. The last one I saw let go did so this past October while I and 5 or 6 others were approaching at 110 + MPH. It's a miracle he didn't get collected but somehow we all missed him.

Just skip to the last 2 minutes or so.

https://youtu.be/7Wuilc6yQhU

I would sell it.

Tech

Around 15:24 in.

SGT_G

I take it a lot of these regular track cars are modified one way or another?

Racingswh

No. Typically engines are left stock. The engine in the car in this video was completely stock. All of the engines I have seen let go have been stock. Some two or three times in the same car. Crate engine after crate engine.

I literally had just had the conversation with the Driver the night before at the hotel about the reliability risks of the LS7 and had given him Fran at RPM's information. He was set on addressing the issues over this off season.

He now has a new Cayman S with paddle shift and essentially gave his Z06 away instead of fixing it.

Unreal

Guy I sold my stock motor two lost 2 stock motors from valve issues. I had several locals fighting over my stock short block because they all needed one. It really opened my eyes to this issue when posting a for sale ad of a ls7 and seeing all the people come out of no where that lost motors and are desperate to find a replacement for a good price. None of them on this forum.