Alright, how bad exactly, is the C6ZO6 valve guide issue?

[gimmie11s]

Heads on the ls platform are cheap as hell and easy as shit to replace.

If I didn't have kids who love to go on rides w me in the "race car" I'd own both a c5z in 405hp flavor and a c6z sitting right next to it.

Something about the c5 fixed roof coupe I will never get over. So damn sexy.

Win and win.

 

[HEMI LOL]

well, not much in confidence. i guess it is really that bad. so find with the heads done it is.

 

[Sinister04L]

Heads on the ls platform are cheap as hell and easy as shit to replace.

If I didn't have kids who love to go on rides w me in the "race car" I'd own both a c5z in 405hp flavor and a c6z sitting right next to it.

Something about the c5 fixed roof coupe I will never get over. So damn sexy.

Win and win.

A properly set up C5Z or FRC is killer. I remember when the FRC first came out and I saw one on the street. HNNNNGGGHHH.

 

[08mojo]

well, not much in confidence. i guess it is really that bad. so find with the heads done it is.

The issue is widespread, but it's really not that big of a deal IMO. You can have the heads rebuilt with new guides pretty inexpensively. But of course, you know how this game goes: once I'm in there, I might as well port and polish the heads. If the heads are being rebuilt, I may as well upgrade the springs, cam, exhaust, intake...and so on.

Be smart when you buy one and inspect any repairs the previous owner may have done to the car. I don't trust anyone--I'd be sure to pull a valve cover and springs to check for excessive play in the guides. OR, for $1,500 to $2,000 you can address the heads and drive the car with peace of mind. To me, that's a small price to pay to really enjoy a C6Z. It truly is a special car, and I hope we will see another big displacement, naturally aspirated, "high" rpm, "lightweight" car in the near future.

 

[kirks5oh]

as stated above either buy one from someone reputable where the work has already been done, or buy one and have the work done yourself. these are truly amazing cars. unfortunately, I don't get much time without my kids, and rwd cars can't be enjoyed much of the year where I live--so I'm trading it in shortly. I've owned my c6z for almost 8 years, and 5 of those years have been at 580rwhp---they are flat-out nasty on the freeway. they turn and stop just about as good as anything you can buy.

 

[Uncle Meat]

48K miles on my '09 C6Z still on stock heads.

U.M.

 

[Blackoyote]

Alternative - buy a newer GS and do HCI, still be under the cost of a decent condition 07 Z. Yeah, it weighs a hair more, but still widebody, good brakes, and dry sump (if you get a manual car).

 

[Serpent]

C6Z should be considered car of the decade. Its still formidable today on the street or strip or road course, it also gets great gas mileage.

 

[ArabianOak]

Here is my real world experience as somebody who had the C6z AND the motor did blow up...

I purchased an 09 C6z with 21k on the ODO...like you I was told by EVERYONE to get steel valves and bronze guides and the car would be golden.

So my first mod was to do just that, along with a custom tune and intake. About 2500 to do those mods. Car made incredible power with just an intake and tune (mine was 485RWHP or something near that).

Less than 1000 miles later i'm driving around 3000 rpms and the motor just turned off. I wasn't even on the car AT ALL. I thought maybe a sensor failed or something along those lines but when I got out the car and popped the hood I saw what every car guy has nightmares about...antifreeze leaking out the intake!

I literally became sick to stomach when I saw that, knowing it was mid summer and my car most likely had a blown engine. I had to wait an hour to get a flatbead tow truck and off to the shop she went. About an hour after she got to the shop my worst nightmare was confirmed...motor was definitely blown but they were not sure how bad. Spark plug number 4 was so bad that they couldn't even get a socket into the hole to pull it.

The next day they called and told me my block had a massive crack in it and I would need a completely new engine, not just the short block...the long block. They said one of my pistons was completely destroyed and chunks of metal were all over my oil pan. A new c6z engine at the time was 15000!

At this point I had some REALLY big decisions to make. Do I go stock or just get an aftermarket engine with forged internals and make HUGE NA power...After doing some research I went with the Texas Speed 441 short block engine and there custom grind race cam. I was promised at least 600RWHP NA. The shop I was using had some used c6z heads and they told me they would use those but have them ported to finish up the block.

After nearly 5 weeks of waiting (and 18k later) for all this shit to come together I got a call and was told my car would be getting dyno'd and finished today. About 2 hours later I got another call and was told my car wasn't making the power they were expecting and they were trying to figure out why...when I asked what it was making they told me 515RWHP!!! Way below my expectations!

For the next week the shop scrambled to replace pushrods (too long, too short etc) but finally decided they had ordered the wrong cam!!! I refused to give them any more money and they did install a different custom grind cam free (which they should have). To make a long story short the car made 580RWHP once it was all said and done...I was happy and the ****er was insanely fast.

The next few weeks were nothing but headaches. I had oil leaks, headers were leaking, weird rattles, engine lights...I was DONE! The shop fixed it all free of charge but I had no faith that this car was going to last. It felt evil to me at this point. I decided I had enough of the C6z and sold it. Huge loss no matter what but I did good on what I got for the car.

Thank God I sold it to my friends dealer, because the guy who bought it blew the engine up (again) less than 2 months later! This was with the indestructible texas speed fully forged 441! I am so glad I didn't sell that car directly to anyone. Someone would be out to kill me if I did!

Anyways, sorry for the long rant but because of what happened to me I had gotten very close with many experts in the c6z community and I learned ONE THING...the heads on that car are a major design flaw. No matter what year or make you buy the stock heads will eventually fail. This is an absolute fact. Some guys got lucky with higher mileage, but they ALL will fail at some point. My friends 07 sounded like he had marbles bouncing around his heads at 22k! He took it in and had the wiggle test done and they were all way out of spec. He sold his car right after.

I made a big mistake by keeping my stock heads when I opted with texas speed 441 short block. If I would have ordered the long block with there heads I would have never had to worry.

From my understanding the internal design of the heads is flawed, GM knows it but will not fess up or fix it. Doesn't matter if you do steel valves with bronze guides (like I did to protect myself). It will still fail.

It's a sad thing too cause that car was ****ing amazing in every single way. I loved it and hated it all at the same time...i'll post some pics of the carnage in the next post.

 

[ArabianOak]

Few pics...not in any order, but I'm sure everyone will figure it out...lol

 

[ArabianOak]

Few more...

 

[CobraKid04]

With a Z06, you can say you have a z06. I would much rather have the rock solid ls3 in the GS.

Full bolt on, mild cam and 100 shot I made 560rwhp and 565 rwtq. In my GS. It's reliable as hell. Na nitrous tune was 455-415.

I wanted a nitrous car, so I could still be N/a for road course. If not, I would have put a supercharger on and made 600+ reliably.

The z is no more rare than a GS. U just get a 427 and wood floors.

 

[SID297]

 

[J.Rovirosa]

Thankfully pulling the heads on a C6 doesn't look nearly as bad as it would be on a Mod-motored Mustang. I've accepted this and the possible dash delamination issues some of these cars face as they get older.

Can't beat the C6Z for the money and hope to find an AO '09 next year.

 

[J.Rovirosa]

Here is my real world experience as somebody who had the C6z AND the motor did blow up...

I purchased an 09 C6z with 21k on the ODO...like you I was told by EVERYONE to get steel valves and bronze guides and the car would be golden.

So my first mod was to do just that, along with a custom tune and intake. About 2500 to do those mods. Car made incredible power with just an intake and tune (mine was 485RWHP or something near that).

Less than 1000 miles later i'm driving around 3000 rpms and the motor just turned off. I wasn't even on the car AT ALL. I thought maybe a sensor failed or something along those lines but when I got out the car and popped the hood I saw what every car guy has nightmares about...antifreeze leaking out the intake!

I literally became sick to stomach when I saw that, knowing it was mid summer and my car most likely had a blown engine. I had to wait an hour to get a flatbead tow truck and off to the shop she went. About an hour after she got to the shop my worst nightmare was confirmed...motor was definitely blown but they were not sure how bad. Spark plug number 4 was so bad that they couldn't even get a socket into the hole to pull it.

The next day they called and told me my block had a massive crack in it and I would need a completely new engine, not just the short block...the long block. They said one of my pistons was completely destroyed and chunks of metal were all over my oil pan. A new c6z engine at the time was 15000!

At this point I had some REALLY big decisions to make. Do I go stock or just get an aftermarket engine with forged internals and make HUGE NA power...After doing some research I went with the Texas Speed 441 short block engine and there custom grind race cam. I was promised at least 600RWHP NA. The shop I was using had some used c6z heads and they told me they would use those but have them ported to finish up the block.

After nearly 5 weeks of waiting (and 18k later) for all this shit to come together I got a call and was told my car would be getting dyno'd and finished today. About 2 hours later I got another call and was told my car wasn't making the power they were expecting and they were trying to figure out why...when I asked what it was making they told me 515RWHP!!! Way below my expectations!

For the next week the shop scrambled to replace pushrods (too long, too short etc) but finally decided they had ordered the wrong cam!!! I refused to give them any more money and they did install a different custom grind cam free (which they should have). To make a long story short the car made 580RWHP once it was all said and done...I was happy and the ****er was insanely fast.

The next few weeks were nothing but headaches. I had oil leaks, headers were leaking, weird rattles, engine lights...I was DONE! The shop fixed it all free of charge but I had no faith that this car was going to last. It felt evil to me at this point. I decided I had enough of the C6z and sold it. Huge loss no matter what but I did good on what I got for the car.

Thank God I sold it to my friends dealer, because the guy who bought it blew the engine up (again) less than 2 months later! This was with the indestructible texas speed fully forged 441! I am so glad I didn't sell that car directly to anyone. Someone would be out to kill me if I did!

Anyways, sorry for the long rant but because of what happened to me I had gotten very close with many experts in the c6z community and I learned ONE THING...the heads on that car are a major design flaw. No matter what year or make you buy the stock heads will eventually fail. This is an absolute fact. Some guys got lucky with higher mileage, but they ALL will fail at some point. My friends 07 sounded like he had marbles bouncing around his heads at 22k! He took it in and had the wiggle test done and they were all way out of spec. He sold his car right after.

I made a big mistake by keeping my stock heads when I opted with texas speed 441 short block. If I would have ordered the long block with there heads I would have never had to worry.

From my understanding the internal design of the heads is flawed, GM knows it but will not fess up or fix it. Doesn't matter if you do steel valves with bronze guides (like I did to protect myself). It will still fail.

It's a sad thing too cause that car was ****ing amazing in every single way. I loved it and hated it all at the same time...i'll post some pics of the carnage in the next post.

Nightmare scenario right there, to be sure. Unfortunate especially after you likely dropped a ton of money in it. Gorgeous car nevertheless!