RobsVette04

I am going to look at a 2007 Z06 with 17,800 miles.

After reading ~20+ pages on the stickied issue of the valve problem, I am starting to second guess myself.

Does anyone have a solid running Z06? What percentage of the engines see issues?

Any information would be helpful!

LFZ

Lmmfao

nitrojunky

http://forums.corvetteforum.com/c6-z...ve-issues.html

Bill Dearborn

It is hard to know how many people have actually had problems since things are repeated over and over. I know of 9 engines that dropped valves including mine. All but one were replaced under GM Warranty. The one that wasn't replaced under warranty was a modified engine that dropped an intake valve but didn't suffer severe damage to the cylinder so the owner replaced the heads at his expense. There were something like 30K LS7 engines shipped in Vettes from the Aug of 05 through Feb of 13. I suspect the number of failures is in the several hundred range. Based on the sticky GM supposedly corrected a machining error at a supplier in Feb. 2011. I have not heard of any failures in any engine produced after that time. However, even if GM didn't actually resolve the problem the production numbers were very low and given the fact that most Vettes aren't driven much it is highly possible that none from that time period will show up during our life times. Over half of the LS7 production from 2011 through 2013 was allocated to the 427 Vert and most of those are sitting on pedestals in environmentally controlled storage locations.

As for a solid running Z06 mine is as solid as it can be. The engine was replaced in Sept. 2011 with an engine produced in May of 2011. Since then it has accumulated 13K miles. There usually is no warning when a valve will drop. No excessive oil consumption, no reduction in performance, no noticeable increase in engine noise. My original engine went 24K miles and ran strong right up to the time the valve head broke off and dropped into the cylinder. Then everything got very quiet.

Bill

RobsVette04

Not really sure how that added anything to my question...?

RFZ

just under 50k with my 07, runs and sounds just like it should.....

ctsv510

The vast majority of people have solid running cars here, at least from the outside. There is little to no indication of any problems before a valve drops and destroys a motor.

Currently about 87% of those tested for valve guide clearance have come back out of GM service specifications, which means if your car was under warranty then GM would replace the heads. It is likely that excessive guide wear is the cause of valve breakage, which will destroy your motor.

We can't predict at this time under exactly what circumstances or guide clearances a valve will break and drop, but the best thing you can do is have the guide clearances measured, and if out of spec then have the head reworked by a competent machine shop. It is then generally recommended to check the guide clearances again down the road to make sure the new guides are not wearing.

In shopping for a Z06, consider those with reworked heads more valuable than those with stock heads assuming a reputable shop did the work, and if you're looking at one with untouched stock heads, budget $150-$300 for a wiggle test and potentially $2k-$3k to have the heads redone if out of spec.

No need to fear these cars, just educate yourself and take the necessary steps to protect it.

RobsVette04

Thanks

RobsVette04

Very well said, thank you for the information.

nitrojunky

pretty much my thoughts on the subject. i've considered this, pondered how incredible this car drives, decided to keep my car for at least a couple more years (probably more than a few more years), and then reworked my heads and resigned myself to doing regular wiggle tests and monitoring blackstone since i went Ti exhaust. i'm in the 87%; my exhaust valves were most definitely OOS. i'm considering regular wiggle tests to be 'preventative maintenance'. i guess most chevy guys aren't accustomed to this, but look at the regularly scheduled maintenance of other super high performance cars, and this isn't totally out of line. what is out of line is the lack of root cause from GM and the fact that we're left to figure it out for ourselves. (for examples of doing things right when there exists a design/manufacturing defect that can crater a high $$$ engine, consider BMW S65 and S85 rod bearing recalls recalls and how porsche handled the recent 991 GT3 rod failures). GM needs to take note of this. i am at the point where i can now afford a new CZ7 if i choose to, but my $$$ may end up somewhere else.

RobsVette04

Well, I guess I have no choice but to go for it.

An extended warranty seems mandatory, so I will certainly look into that.

LMB-Z

My 06 had 45k miles on it with no problems and no ticking noise at all. Ran perfect. I just replaced my heads just for peace of mind. I did not have the wiggle test done and have no idea if my heads were out of spec or not. I did ask the shop that did the work to check, but they never did. I guess it was too much trouble.

I would say if the price is right, go for it. You may want to look into having the heads done at a later date. Good luck.

Unreal

Either get a warranty or plan on checking the heads on regular internals and replace guides when they are out of spec. It is as simple as that. I pretty much consider them a wear item on an ls7 that needs to be checked and replaced when needed. Just like bushings, clutch, ball joints, tires, brake pads, etc. It is just something to monitor and deal with. Keep $2-4k around in case repairs need to be made.

Homeboy77

Ugh. My mechanic just called and told me that two of my valve guides are so bad that they have to be bored and sleeved. 36K miles. Luckily I decided to have them worked on before a dropped valve. Oh well. Still love my Z.

propain

You can pay for an extended warranty or you can pay to have the issue addressed. Both are probably close in price. If you plan on keeping the car only for the term of the warranty then I say warranty. If not address the issue if its a problem with your car.

One thing I will warn you about is if you are going to get the extended warranty make sure the car is not or has never been tuned. They will deny the claim if it had.

z76232

Just had the wiggle test done on my 06 with 16K miles on it. Cost me $280. All valves were in spec .0012 - .0025 #7 exhaust being the .0025. 2006 Z has 16k miles on it now and he said that he'd like to come back at 30k and check just the one bank again. Like a friend said, at the rate I'm going I'll see him again in about 8 more years.

Unreal

Another advantage of addressing the heads over a warranty is it gives you the freedom to do mods. These cars are boring stock IMO. Atleast do a intake/headers/tune and get a solid 40-50rwhp and work on suspension/brakes/etc.

LFZ

You buy Z06 and read this forum = Get heads done.

You buy Z06 and don't read this forum = Just drive it and enjoy.

Unreal

Yep, sold my stock motor to a guy who doesn't read the forum and dropped a valve. I'm glad there is a market for stock ls7 short blocks so I could upgrade to an LSX setup. Another guy at a car show dropped one and wasn't on here, and was searching for a motor since he was out of warranty. Reading the forum causes the issue for sure.

It isn't just replace heads for the fun of it, get them checked and if they are worn excessively then fix them. Just like you don't replace brake pads every 10k miles but if they are worn and about to be backing plate on rotor it would make sense to replace them.

crazed_z06

My 2008 has 62k miles and runs fine.

EDIT: For now..