[Z06] Stock engine dropped valve, GM won't warranty
01-02-2010, 01:30 PM
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Racer
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Stock engine dropped valve, GM won't warranty
Finally got back from Christmas vacation and the letter I requested from GM was in the mail. The formal reason they gave for not fixing the engine is because their warranty only covers " defective materials and workmanship". In my case, GM said that there was no evidence of either defective materials or defective workmanship, so they are not responsible. I think this one is going to court for sure. The following is a summary of what happened since September.
The car is a 2007 Canadian model bought new from a local dealer in 2006. The engine is completely stock, no tune, no exhaust, no cam, not even an aftermarket air cleaner. The car has 18,000km (11,000 miles) on it when the engine blew in September during a track day.
the car was mainly driven on the streets and had less than 100 track miles. I did one session back in June when I was instructing, ran out of brakes before the session was over. In September, I did one session in the morning and the car ran perfect. I was just finishing my 4th lap during my second session when the engine quit. All together, there was less than three sessions on the track. The engine lost power during corner exit when I dipped into the throttle.
Dealer pulled head and found both valves broken, a crack in the piston and a bent push rod. Valve springs were intact. GM hired a third party local engineer to look at the failure as well as sending samples of all fluids to lab for testing. Nine weeks later, dealer called and said GM won't warranty the engine because the engineer found no defective material or workmanship. I asked for a copy of the engineer's report and received a copy. It was a one and a quarter page letter documenting what the engineer saw at the dealership, as well as looking at some of the broken parts in detail under a microscope. At the end of the letter, the engineer said it is his opinion that there is no defective material and workmanship. The engineer did confirm that the exhaust valve head is missing and probably discharged into the exhaust. He also noticed that the exhuast valve stem has signs of material transfer (galling/dragging inside the valve guide) and possibly due to overheating. But his final conclusion is that there is no evidence of material defect or workmanship defect. As a registered professional engineer myself, I have real issues with this report, and I am pretty sure the courts will have issues with it too. The dealership gave me GM's local district service manager's phone number but she never returned my calls. Apparently, she is the one who decided that the engineer's report is deemed adequate to void the warranty, even though there was no root cause established for the engine failure. I met with the dealership owner and his service department staffs and fired off a written respond on what I think about the engineer's report and GM's decision. In my letter, I questioned the wisdom for GM to hire a local engineer rather than using one of their own powertrain engineers who specializes in the LS7. I was told to contact GM's 1-800 number for a request to review this case. I called and mentioned that they should really look at the engine more closely by one of their own engineers. In early December, the case manager called and said GM will back their local distict service manager's decision and no warranty will be provided. I asked for a formal written decision stating the reason for denying warranty and he promised it will be sent before Christmas. I called the dealership to ask them to remove the exhaust and look for the missing exhaust valve head since it will be impossible for it to make it pass the cat. Dealer called back the next day and said they can't find the valve head in the exhaust. I had the car towed to an independent shop after that and picked up all the parts that were removed off the engine. With the holidays, I haven't had time to start looking into the engine. I am fortunate that I have the engineering contacts and experience to carry out the failure investigation further than what GM has done so far. I can imagine what a typical owner needs to go thru to prove GM wrong if they use " ...we found no defective material or workmanship in the car...." as a reason to deny warranty.
Any product is only as good as the company that stands behind it. This is my second GM purchase, the other one was also a new Corvette. I am pretty sure I won't be buying another car from GM in the future after this.
The car is a 2007 Canadian model bought new from a local dealer in 2006. The engine is completely stock, no tune, no exhaust, no cam, not even an aftermarket air cleaner. The car has 18,000km (11,000 miles) on it when the engine blew in September during a track day.
the car was mainly driven on the streets and had less than 100 track miles. I did one session back in June when I was instructing, ran out of brakes before the session was over. In September, I did one session in the morning and the car ran perfect. I was just finishing my 4th lap during my second session when the engine quit. All together, there was less than three sessions on the track. The engine lost power during corner exit when I dipped into the throttle.
Dealer pulled head and found both valves broken, a crack in the piston and a bent push rod. Valve springs were intact. GM hired a third party local engineer to look at the failure as well as sending samples of all fluids to lab for testing. Nine weeks later, dealer called and said GM won't warranty the engine because the engineer found no defective material or workmanship. I asked for a copy of the engineer's report and received a copy. It was a one and a quarter page letter documenting what the engineer saw at the dealership, as well as looking at some of the broken parts in detail under a microscope. At the end of the letter, the engineer said it is his opinion that there is no defective material and workmanship. The engineer did confirm that the exhaust valve head is missing and probably discharged into the exhaust. He also noticed that the exhuast valve stem has signs of material transfer (galling/dragging inside the valve guide) and possibly due to overheating. But his final conclusion is that there is no evidence of material defect or workmanship defect. As a registered professional engineer myself, I have real issues with this report, and I am pretty sure the courts will have issues with it too. The dealership gave me GM's local district service manager's phone number but she never returned my calls. Apparently, she is the one who decided that the engineer's report is deemed adequate to void the warranty, even though there was no root cause established for the engine failure. I met with the dealership owner and his service department staffs and fired off a written respond on what I think about the engineer's report and GM's decision. In my letter, I questioned the wisdom for GM to hire a local engineer rather than using one of their own powertrain engineers who specializes in the LS7. I was told to contact GM's 1-800 number for a request to review this case. I called and mentioned that they should really look at the engine more closely by one of their own engineers. In early December, the case manager called and said GM will back their local distict service manager's decision and no warranty will be provided. I asked for a formal written decision stating the reason for denying warranty and he promised it will be sent before Christmas. I called the dealership to ask them to remove the exhaust and look for the missing exhaust valve head since it will be impossible for it to make it pass the cat. Dealer called back the next day and said they can't find the valve head in the exhaust. I had the car towed to an independent shop after that and picked up all the parts that were removed off the engine. With the holidays, I haven't had time to start looking into the engine. I am fortunate that I have the engineering contacts and experience to carry out the failure investigation further than what GM has done so far. I can imagine what a typical owner needs to go thru to prove GM wrong if they use " ...we found no defective material or workmanship in the car...." as a reason to deny warranty.
Any product is only as good as the company that stands behind it. This is my second GM purchase, the other one was also a new Corvette. I am pretty sure I won't be buying another car from GM in the future after this.
Last edited by hoefi; 01-02-2010 at 01:42 PM.
01-02-2010, 01:39 PM
#3
Team Owner
the engine blew in September during a track day.
01-02-2010, 01:43 PM
#5
Team Owner
while I agree the car should be able to be driven hard.... in fact it was Dave Hill who said something to the effect you can take this car to the track on Sunday and drive it to work on Monday.....if they think it was abused he is going to have a rough go of it and their pockets are deeper
01-02-2010, 01:45 PM
#6
Safety Car
01-02-2010, 01:46 PM
#7
Instructor
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Don't mention you were running it on a track when the dropped valve occured.
There was also a know problem with Z06's made between jan 2007 and june 2007 in regards to this malfunction.
There was also a know problem with Z06's made between jan 2007 and june 2007 in regards to this malfunction.
01-02-2010, 01:47 PM
#8
Safety Car
01-02-2010, 01:47 PM
#9
Team Owner
01-02-2010, 01:48 PM
#10
Team Owner
01-02-2010, 01:49 PM
#11
Team Owner
and might I add we have engine builders from Wixom on the site....
01-02-2010, 01:55 PM
#14
Safety Car
01-02-2010, 02:00 PM
#15
Team Owner
I dunno about you but my bank account for attorney fees is probably far less substantial than GM's
01-02-2010, 02:01 PM
#16
Team Owner
01-02-2010, 02:02 PM
#17
Safety Car
01-02-2010, 02:12 PM
#18
Burning Brakes
Member Since: Apr 2007
Location: Rochester New Hampshire
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Best of luck to you. GM definately needs to stand by their warranty. I hate to say it but I would not buy another GM vehicle either if I were you. Keep us posted as to the final outcome. Marc L.
01-02-2010, 02:13 PM
#19
Team Owner
01-02-2010, 02:40 PM
#20
Le Mans Master
In civil litigation you may be subject to discovery, which can mean turning over copies of anything you have written on the subject.