mpmussel
11-12-2005, 12:36 PM
Hi guys,
I'm normally a corvetteforum.com guy but there is surprisingly little info on this topic there. I have a 2001 Corvette Coupe (LS1). Have had the car for 10,000 miles. I drive the car hard (often full throttle acceleration to redline and toe-and-heel mid-to-high rpm matched rev downshifts) but I don't abuse it (i.e. bounce it off the rev limiter). This driving would put me in the 1 or 2% group of Corvette drivers. Anyway, the car burns about 1 quart/1.000 mi. In addition to this, there is some moderate piston slap noise when the car is cold (I live in Florida, so I don't know what it would do in a bone cold environment). Bought the car used and it was just outside of the warranty. One of the mechs at the dealer I bought it from had had 3 C5 Corvettes of his own and had piston slap problems on 2 of them. He confirmed my engine noise as piston slap. He had his pistons replaced under extended warranty and said it cured 90% of the problem. Between talking to him and my own research, my understanding of the LS1 problems is this:
--High oil consupmtion problem was found on a small percentage of 2001 and older engines, especially those where engine rpms are 3-4,000 rpm or higher on deceleration (i.e. engine braking) for significant amounts of time (i.e my driving style). This engine parameter is supposedly condusive to "ring flutter" which allows blowby and the resulting high oil consumption. The fact that most Corvette drivers don't drive their cars very hard probably contributes to the percentage of problem engines being low. The problem was also worsened by the design of the piston. GM's fix for this was a ring kit which replaced 2 of the 3 rings.
--Piston slap conditions can also lead to high oil consumption. Do to piston slap and the related high oil consumption complaints, GM redesigned the pistons and started building LS1s with these in the 2002 model year. To my understanding the new 2002 redesigned piston almost eliminated the piston slap and high oil consumption problems. As per my discussions with my mechanic friend, he had heard the piston was again redesigned a 2nd time after the initial 2002 redesign.
My dealer is ready to replace my pistons and have GM foot the bill, using my high oil consumption as evidence rather than piston slap (I have told them I have some piston slap when the motor is cold, but they have never listened to it. I have been runnig an oil consumption test with them to gain data points and ammunition to use against GM and this is what they are using to get GM to pay for the piston replacement). I thought the 2002 spec pistons had solved this problem but from reading some of your threads, there are still 2002 and newer cars with piston slap. Obviously we are on a site dedicated to this problem so we are not hearing from owners who's cars are fine. There are also people out there who might have the problem but don't have the mechanical sense to loosen a bolt much less identify an abnormal engine sound.
I'm wondering what percentage of the 2002 and newer cars are still having the problem?
Those of you with piston slap problems, are you also having oil consumption problems? If so, is you engine 2001 or older OR 2002 or newer? (My dealer has told me I may still have some oil consumption with the new pistons. I also talked to another dealer that did the piston swap on a 2001 Corvette and said it fixed the piston slap problem but now the car was burning oil.)
Does anyone know about a 2nd piston redesign after the first 2002 redesign? Do you have part #s?
Thanks for all your help. I told the dealer I would bring the car in Mon for the teardown.
Mark
I'm normally a corvetteforum.com guy but there is surprisingly little info on this topic there. I have a 2001 Corvette Coupe (LS1). Have had the car for 10,000 miles. I drive the car hard (often full throttle acceleration to redline and toe-and-heel mid-to-high rpm matched rev downshifts) but I don't abuse it (i.e. bounce it off the rev limiter). This driving would put me in the 1 or 2% group of Corvette drivers. Anyway, the car burns about 1 quart/1.000 mi. In addition to this, there is some moderate piston slap noise when the car is cold (I live in Florida, so I don't know what it would do in a bone cold environment). Bought the car used and it was just outside of the warranty. One of the mechs at the dealer I bought it from had had 3 C5 Corvettes of his own and had piston slap problems on 2 of them. He confirmed my engine noise as piston slap. He had his pistons replaced under extended warranty and said it cured 90% of the problem. Between talking to him and my own research, my understanding of the LS1 problems is this:
--High oil consupmtion problem was found on a small percentage of 2001 and older engines, especially those where engine rpms are 3-4,000 rpm or higher on deceleration (i.e. engine braking) for significant amounts of time (i.e my driving style). This engine parameter is supposedly condusive to "ring flutter" which allows blowby and the resulting high oil consumption. The fact that most Corvette drivers don't drive their cars very hard probably contributes to the percentage of problem engines being low. The problem was also worsened by the design of the piston. GM's fix for this was a ring kit which replaced 2 of the 3 rings.
--Piston slap conditions can also lead to high oil consumption. Do to piston slap and the related high oil consumption complaints, GM redesigned the pistons and started building LS1s with these in the 2002 model year. To my understanding the new 2002 redesigned piston almost eliminated the piston slap and high oil consumption problems. As per my discussions with my mechanic friend, he had heard the piston was again redesigned a 2nd time after the initial 2002 redesign.
My dealer is ready to replace my pistons and have GM foot the bill, using my high oil consumption as evidence rather than piston slap (I have told them I have some piston slap when the motor is cold, but they have never listened to it. I have been runnig an oil consumption test with them to gain data points and ammunition to use against GM and this is what they are using to get GM to pay for the piston replacement). I thought the 2002 spec pistons had solved this problem but from reading some of your threads, there are still 2002 and newer cars with piston slap. Obviously we are on a site dedicated to this problem so we are not hearing from owners who's cars are fine. There are also people out there who might have the problem but don't have the mechanical sense to loosen a bolt much less identify an abnormal engine sound.
I'm wondering what percentage of the 2002 and newer cars are still having the problem?
Those of you with piston slap problems, are you also having oil consumption problems? If so, is you engine 2001 or older OR 2002 or newer? (My dealer has told me I may still have some oil consumption with the new pistons. I also talked to another dealer that did the piston swap on a 2001 Corvette and said it fixed the piston slap problem but now the car was burning oil.)
Does anyone know about a 2nd piston redesign after the first 2002 redesign? Do you have part #s?
Thanks for all your help. I told the dealer I would bring the car in Mon for the teardown.
Mark