[Z06] Another exploding LS7
06-08-2015, 08:01 PM
#41
Le Mans Master
I think this point is missed on a lot of people who I sense assume all Z06 model years are somewhat homogenous in terms of production.
Nearly 80% of all Z06s (not counting 427 verts) were built before the 2009 MY, that is huge in terms of real life owners who have to decide how to manage the valvetrain issues... or not.
Nearly 80% of all Z06s (not counting 427 verts) were built before the 2009 MY, that is huge in terms of real life owners who have to decide how to manage the valvetrain issues... or not.
06-08-2015, 08:35 PM
#42
Instructor
Thread Starter
B4: I for one have appreciated yours and other's condolences.
Should have or not, it does still really suck to be stuck with a 5 figure repair.
06-08-2015, 10:07 PM
#44
Drifting
thanks AZDAN, interesting to hear about the class action and the production numbers as well, so am I completely wasting my time either going to the dealer (figured should be the first stop) and then letter writing? sounds like it.
B4: I for one have appreciated yours and other's condolences. Should have or not, it does still really suck to be stuck with a 5 figure repair.
B4: I for one have appreciated yours and other's condolences.
Should have or not, it does still really suck to be stuck with a 5 figure repair.
06-09-2015, 12:38 AM
#45
Melting Slicks
There is no harm in asking GM if they will cover it. I would start by writing a letter to the CEO since a dealer probably may not forward your request due to the car being so far out of warranty.
Let us know what caused the failure. Based on what you have said so far it doesn't necessarily have to be due to a valve guide issue.
How fast were you going in the Esses and at which turn were you when it popped? That is a tricky place to have an engine let loose and spill oil all over the surface.
Mine let go just about where the start/finish flag station is on the front straight about 4 years ago with the engine turning about 6800 rpm. It popped at about 24K miles. Based on the dealer's tear down to find the cause it definitely looked like a dropped exhaust valve head but the guides were not checked and there is no way to know for sure the guides caused the problem. I had about 4K track miles on my engine and it could have just as easily been a weakened valve spring that allowed the valve to float at 6800 rpm and hit the piston Vs anything else.
Bill
Let us know what caused the failure. Based on what you have said so far it doesn't necessarily have to be due to a valve guide issue.
How fast were you going in the Esses and at which turn were you when it popped? That is a tricky place to have an engine let loose and spill oil all over the surface.
Mine let go just about where the start/finish flag station is on the front straight about 4 years ago with the engine turning about 6800 rpm. It popped at about 24K miles. Based on the dealer's tear down to find the cause it definitely looked like a dropped exhaust valve head but the guides were not checked and there is no way to know for sure the guides caused the problem. I had about 4K track miles on my engine and it could have just as easily been a weakened valve spring that allowed the valve to float at 6800 rpm and hit the piston Vs anything else.
Bill
I've started my letter to Ms. Barra, but probably should also talk with the dealer 1st? not sure. sorry to hear about yours and at least mine was at a lower speed. I was coming out of turn 2 probably about 80-85in 3rd and I'm guessing 4k- 4500 RPM ? and was bleeding on the throttle and transitioning into turn 3 when it lost power, then popped. I pulled offline outside of 3 and came to a stop just before the flag station between 3 and 4. only 1 car got caught in the oil slick and suffered minor damage in the wall. I've got 16 days at the Glen now and a couple days a the little Englishtown road course. As one poster mentioned, it did have 9k miles on it when I bought it, but no rock chips at the telltale rear brake inlet form track days, was kept covered in the garage and still looked and smelled new, FTIW. But sure, buyer beware. I've put the remaining 16,500 on it myself, changing oil after every track day etc. and had no warnings or sounds or oil use.
06-09-2015, 02:05 AM
#46
Well, add me to the list of the LS7 owners who blew up a 427
I had checked the posts about the valve guide issue and had surmised (incorrectly) a couple years ago when I bought my 07 with 9k miles on it. It currently has 23k miles and I almost completed my 16 track day at Watkins Glen since 2012 when I bought the car. I trailered the car there for the first time - fortunately - and no one was injured from the resulting oil slick on the track between turns 2 and 3 in the Esses. I was running about 4k-4500 RPM, I'm guessing and I lost power, heard a loud pop and saw some debris and white smoke coming out of both sides of the hood. I would say we could call this a catastrophic failure as the preliminary investigation has revealed the front left corner of the block is gone. Here's a view from below. The first suspect is the valve guides, but I'll be looking deeper this weekend. I was 2-1/2 laps into the last session of the 2 day event and feel bad for the rest of the drivers in the group who lost the last 15-20 mins of the session and the M3 driver caught in the slick who crunched the wall with his rear bumper. Of course up until then, I was having a great time and the car was flawless. I had no indications prior. I'll be digging up the old posts on the valve guide issues and planning my next steps...anyone who tracks these beasts needs to check those valve guides! 
I had checked the posts about the valve guide issue and had surmised (incorrectly) a couple years ago when I bought my 07 with 9k miles on it. It currently has 23k miles and I almost completed my 16 track day at Watkins Glen since 2012 when I bought the car. I trailered the car there for the first time - fortunately - and no one was injured from the resulting oil slick on the track between turns 2 and 3 in the Esses. I was running about 4k-4500 RPM, I'm guessing and I lost power, heard a loud pop and saw some debris and white smoke coming out of both sides of the hood. I would say we could call this a catastrophic failure as the preliminary investigation has revealed the front left corner of the block is gone. Here's a view from below. The first suspect is the valve guides, but I'll be looking deeper this weekend. I was 2-1/2 laps into the last session of the 2 day event and feel bad for the rest of the drivers in the group who lost the last 15-20 mins of the session and the M3 driver caught in the slick who crunched the wall with his rear bumper. Of course up until then, I was having a great time and the car was flawless. I had no indications prior. I'll be digging up the old posts on the valve guide issues and planning my next steps...anyone who tracks these beasts needs to check those valve guides! Did you not see any power loss with run-n-, at a track, that was an still is 1 of the best MOTOR CROSS tracks out on the west coast.
an you were at a 2 day party, Hell the last time i saw a 2 day event on the east coast, i was run-in- sweeper, 4 the 1st time,with ridge riders mc. Hell you talk-in- about a party with a mixed blood of people. waterlooe village was a place that was, an now is no more thanks to out side ers, just like the american pharaoh horse , won the 38 year old race with out a try. (3 TIMES) hell when i was a little tot did not even have a clue about horse race-in- went to a track with my xes family the mfer won,were your best, pictures are commin.
:crazy2 :
06-09-2015, 05:57 AM
#47
Safety Car
Sorry,if I'am sound in like a bitch, but how the hell.
Did you not see any power loss with run-n-, at a track, that was an still is 1 of the best MOTOR CROSS tracks out on the west coast.
an you were at a 2 day party, Hell the last time i saw a 2 day event on the east coast, i was run-in- sweeper, 4 the 1st time,with ridge riders mc. Hell you talk-in- about a party with a mixed blood of people. waterlooe village was a place that was, an now is no more thanks to out side ers, just like the american pharaoh horse , won the 38 year old race with out a try. (3 TIMES) hell when i was a little tot did not even have a clue about horse race-in- went to a track with my xes family the mfer won,were your best, pictures are commin.:crazy2 :
Did you not see any power loss with run-n-, at a track, that was an still is 1 of the best MOTOR CROSS tracks out on the west coast.
an you were at a 2 day party, Hell the last time i saw a 2 day event on the east coast, i was run-in- sweeper, 4 the 1st time,with ridge riders mc. Hell you talk-in- about a party with a mixed blood of people. waterlooe village was a place that was, an now is no more thanks to out side ers, just like the american pharaoh horse , won the 38 year old race with out a try. (3 TIMES) hell when i was a little tot did not even have a clue about horse race-in- went to a track with my xes family the mfer won,were your best, pictures are commin.
:crazy2 :
06-09-2015, 09:50 AM
#48
Drifting
06-09-2015, 12:01 PM
#52
Safety Car
06-09-2015, 12:24 PM
#53
Tech Contributor
Member Since: Oct 1999
Location: Charlotte, NC (formerly Endicott, NY)
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I've started my letter to Ms. Barra, but probably should also talk with the dealer 1st? not sure. sorry to hear about yours and at least mine was at a lower speed. I was coming out of turn 2 probably about 80-85in 3rd and I'm guessing 4k- 4500 RPM ? and was bleeding on the throttle and transitioning into turn 3 when it lost power, then popped. I pulled offline outside of 3 and came to a stop just before the flag station between 3 and 4. only 1 car got caught in the oil slick and suffered minor damage in the wall. I've got 16 days at the Glen now and a couple days a the little Englishtown road course. As one poster mentioned, it did have 9k miles on it when I bought it, but no rock chips at the telltale rear brake inlet form track days, was kept covered in the garage and still looked and smelled new, FTIW. But sure, buyer beware. I've put the remaining 16,500 on it myself, changing oil after every track day etc. and had no warnings or sounds or oil use.
Once you resolve the engine replacement and get back to the Glen I suggest you do what I do in the Esses and what I tell my students to do. As you come out of T1 accelerate quickly in 3rd gear and shift to 4th before you get to the T2 (beginning of Esses) turn in point. This will have you apexing the turn in the high 90s low triple digit speeds (if you are on GY EMTs they can easily handle 100+ speed at the apex). If you are on the correct line you should be very close to wide open throttle as you exit T2 for T3 (I always had an issue with my C6Z trying to go through 3 at WOT since the backend wanted to walk right on me as I crested the hill, some guys with the right setup and the right size and material gonads can do it wide open). This will put you into the entrance to T4 at 120 to 125 and exiting it at around 140 to 143.
Using 3rd gear entering the Esses limits your speed since you can only get 123 mph peak in the gear and breathing off the throttle to correct a yaw problem (in T2/T3) can get problematic when you are in 3rd since the car reacts badly due to the torque change. Shifting to 4th is possible in the short straight from T3 to T4 but that can still leave you short on speed. A lot of guys shift to 5th in that straight. I keep mine in 4th and peak out in the upper 150s (shift light is blinking) right at the bus stop braking point. The guys who use 5th may get 5 or so more mph.
Bill
06-09-2015, 08:30 PM
#54
Team Owner
While the rest of us need to check our guides periodically, you may need to have your liver checked.
06-09-2015, 08:48 PM
#55
Drifting
06-09-2015, 10:07 PM
#56
Race Director
I may have seen his posts at some point but the name isn't ringing a bell. Thumbs up to you if you can translate gibberish. I'm very good at literal interpretation but when words and thoughts get scrambled and fragmented I don't have a chance. 
06-10-2015, 05:55 AM
#57
Instructor
Thread Starter
It won't hurt to involve the dealer especially if you have let them do work on the car so they know you and the car.
Once you resolve the engine replacement and get back to the Glen I suggest you do what I do in the Esses and what I tell my students to do. As you come out of T1 accelerate quickly in 3rd gear and shift to 4th before you get to the T2 (beginning of Esses) turn in point. This will have you apexing the turn in the high 90s low triple digit speeds (if you are on GY EMTs they can easily handle 100+ speed at the apex). If you are on the correct line you should be very close to wide open throttle as you exit T2 for T3 (I always had an issue with my C6Z trying to go through 3 at WOT since the backend wanted to walk right on me as I crested the hill, some guys with the right setup and the right size and material gonads can do it wide open). This will put you into the entrance to T4 at 120 to 125 and exiting it at around 140 to 143.
Using 3rd gear entering the Esses limits your speed since you can only get 123 mph peak in the gear and breathing off the throttle to correct a yaw problem (in T2/T3) can get problematic when you are in 3rd since the car reacts badly due to the torque change. Shifting to 4th is possible in the short straight from T3 to T4 but that can still leave you short on speed. A lot of guys shift to 5th in that straight. I keep mine in 4th and peak out in the upper 150s (shift light is blinking) right at the bus stop braking point. The guys who use 5th may get 5 or so more mph.
Bill
Once you resolve the engine replacement and get back to the Glen I suggest you do what I do in the Esses and what I tell my students to do. As you come out of T1 accelerate quickly in 3rd gear and shift to 4th before you get to the T2 (beginning of Esses) turn in point. This will have you apexing the turn in the high 90s low triple digit speeds (if you are on GY EMTs they can easily handle 100+ speed at the apex). If you are on the correct line you should be very close to wide open throttle as you exit T2 for T3 (I always had an issue with my C6Z trying to go through 3 at WOT since the backend wanted to walk right on me as I crested the hill, some guys with the right setup and the right size and material gonads can do it wide open). This will put you into the entrance to T4 at 120 to 125 and exiting it at around 140 to 143.
Using 3rd gear entering the Esses limits your speed since you can only get 123 mph peak in the gear and breathing off the throttle to correct a yaw problem (in T2/T3) can get problematic when you are in 3rd since the car reacts badly due to the torque change. Shifting to 4th is possible in the short straight from T3 to T4 but that can still leave you short on speed. A lot of guys shift to 5th in that straight. I keep mine in 4th and peak out in the upper 150s (shift light is blinking) right at the bus stop braking point. The guys who use 5th may get 5 or so more mph.
Bill
Bob Henderson was my instructor and taught the same thing - signed me off and this was my first solo run of this event. But these are good numbers for me to have - appreciate it. Wish I had started up there before you left
I had missed completing the shift before T2 so was going to ease off in T4. I had been running the whole thing in 4th until this year (April event and this one) and only really missed being in 3rd at the toe of the boot. On the plus side, Bob had his C7Z and the 2 afternoon sessions finally dried out after 1.5 days of rain and mist, so i got a few hot laps in that baby. Holy cow, what a ride! That car and he really go, my cheeks were sore from the permanent grin! I was inspired and so the next 2 -1/3 laps in my own car with my Conti G5000's were some of the best I've had! right up until ...
. I actually have the same photo as your avatar and came to rest just in front of that spot. But I will be back, the addiction is too strong...
Last edited by Johns07Z; 06-10-2015 at 06:01 AM. Reason: Add content
06-10-2015, 10:51 AM
#58
Safety Car
sorry,if i'am sound in like a bitch, but how the hell.
Did you not see any power loss with run-n-, at a track, that was an still is 1 of the best motor cross tracks out on the west coast.
An you were at a 2 day party, hell the last time i saw a 2 day event on the east coast, i was run-in- sweeper, 4 the 1st time,with ridge riders mc. Hell you talk-in- about a party with a mixed blood of people. Waterlooe village was a place that was, an now is no more thanks to out side ers, just like the american pharaoh horse , won the 38 year old race with out a try. (3 times) hell when i was a little tot did not even have a clue about horse race-in- went to a track with my xes family the mfer won,were your best, pictures are commin.:crazy2 :
Did you not see any power loss with run-n-, at a track, that was an still is 1 of the best motor cross tracks out on the west coast.
An you were at a 2 day party, hell the last time i saw a 2 day event on the east coast, i was run-in- sweeper, 4 the 1st time,with ridge riders mc. Hell you talk-in- about a party with a mixed blood of people. Waterlooe village was a place that was, an now is no more thanks to out side ers, just like the american pharaoh horse , won the 38 year old race with out a try. (3 times) hell when i was a little tot did not even have a clue about horse race-in- went to a track with my xes family the mfer won,were your best, pictures are commin.
:crazy2 :
04-23-2016, 11:50 AM
#59
Instructor
Thread Starter
) who turned me on to Karl Chevy Performance Parts (Thanks Adam!) in Ankeny, Iowa who gave me a great price and customer service on a new LS7. With all new belts and hoses, oil cooler, as well as the Lingenfelter oil reservoir upgrade, I'm back on the streets and hopefully soon the track as well. Frank, who typically works on older muscle cars, did me a favor and put my baby back together and its good as new, probably better than new.Looking at the old motor, number one cylinder's exhaust valve appears to have stuck and I have several pieces of it and the piston along with other chunks of aluminum block as souvenirs.
My brother has a nearly identical silver 07 Z and attended the GT Tire NCM event that we were going to share in August last year. Day two saw his motor grenade as well,
After his own research and my suggestion, Karl Chevy supplied another new LS7 to our family last year. Still hoping to hear something on the class action suit, but neither of us are holding our breath! I'll get some photos downloaded and add to the post, but wanted to answer back.
04-23-2016, 05:10 PM
#60
Do not track car and it has 28k on it but still do not like stressing over it
Sucks to spend 4k on a car that should not need it but oh well.