Piston Ring Failure (lots of pics of inside an LNF)
11-24-2009, 09:54 PM
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Piston Ring Failure (lots of pics of inside an LNF)
For those who don't know, I recently had a piston ring give out on my SS/TC. The cause was ruled a manufacturing fault and the dealer was outstanding about it, being honest about the cause despite my aftermarket parts and treating me very well. Definately buying there again.
Background story... keep scrolling for the pics:
I started noticing during long trips (5 hours each way) that if I was cruising for a long time, the car would misfire and/or make a "putting" sound if I tried to get on it to pass somebody for instance. Sometimes it would be RPM dependent and sometimes just pedal dependent. After getting into town it would also have a bit of a rough idle sometimes too. I attributed it to the fuel trims skewing a lot during constant cruising for a long time at one RPM and speed. It took about a day usually around town for it to start driving fine again. It always seemed more prone to it on rainy and/or cold days.
I started having trouble if I'd NLS sometimes. It would stumble for a split second and then catch itself and keep going. I got a flashing misfire CEL a time or two.
Eventually I got a solid CEL for a misfire on cylinder 1 and took it in. The dealer did a compression test (140psi) and changed the plug and coil pack on cylinder one and the car seemed fine for about a week to a week and a half.
I eventually got a cylinder 1 misfire CEL again (flashing and then solid) and on the last day before I took it in again I started having a smoke show whenever I'd stop. Compression tested at 90psi and this time the (new) spark plug had oil on it.
They tore down the engine and at first didn't see any issues. They eventually found stress cracks in the piston between the first and second compression rings. These cracks caused the first compression ring to push up onto the bottom ledge of the top land and seize there. Then with normal usage and the piston expanding with it stuck there, the ring snapped in two places and oil started getting by, causing misfires and later smoke.
They replaced the piston/rod (they come as one), the gaskets/seals, and spark plugs. It's running great now.
Diagram to help people understand/visualize:
Below are pictures of the piston and others of the disassembled LNF:
Piston with one of the cracks visible (sorry it's fuzzy... camera wouldn't focus)
Head with valve cover
Inside oil pan (Made in Israel apparently, as it's stamped in there)
Parts that had to be removed (notice CIA CP and broken-in CIA DP)
Top of block and turbo
Inside the block and cylinders (notice the vacuum tank in front of the cylinders)
Other views of the turbo
Exhaust header (notice the piping division evident on the inside, for the twin scroll turbo design)
Intake manifold
Inside the head and various other pictures
Direct Injection fuel rail and injectors
Background story... keep scrolling for the pics:
I started noticing during long trips (5 hours each way) that if I was cruising for a long time, the car would misfire and/or make a "putting" sound if I tried to get on it to pass somebody for instance. Sometimes it would be RPM dependent and sometimes just pedal dependent. After getting into town it would also have a bit of a rough idle sometimes too. I attributed it to the fuel trims skewing a lot during constant cruising for a long time at one RPM and speed. It took about a day usually around town for it to start driving fine again. It always seemed more prone to it on rainy and/or cold days.
I started having trouble if I'd NLS sometimes. It would stumble for a split second and then catch itself and keep going. I got a flashing misfire CEL a time or two.
Eventually I got a solid CEL for a misfire on cylinder 1 and took it in. The dealer did a compression test (140psi) and changed the plug and coil pack on cylinder one and the car seemed fine for about a week to a week and a half.
I eventually got a cylinder 1 misfire CEL again (flashing and then solid) and on the last day before I took it in again I started having a smoke show whenever I'd stop. Compression tested at 90psi and this time the (new) spark plug had oil on it.
They tore down the engine and at first didn't see any issues. They eventually found stress cracks in the piston between the first and second compression rings. These cracks caused the first compression ring to push up onto the bottom ledge of the top land and seize there. Then with normal usage and the piston expanding with it stuck there, the ring snapped in two places and oil started getting by, causing misfires and later smoke.
They replaced the piston/rod (they come as one), the gaskets/seals, and spark plugs. It's running great now.
Diagram to help people understand/visualize:
Below are pictures of the piston and others of the disassembled LNF:
Piston with one of the cracks visible (sorry it's fuzzy... camera wouldn't focus)
Head with valve cover
Inside oil pan (Made in Israel apparently, as it's stamped in there)
Parts that had to be removed (notice CIA CP and broken-in CIA DP)
Top of block and turbo
Inside the block and cylinders (notice the vacuum tank in front of the cylinders)
Other views of the turbo
Exhaust header (notice the piping division evident on the inside, for the twin scroll turbo design)
Intake manifold
Inside the head and various other pictures
Direct Injection fuel rail and injectors
Last edited by Stamina; 11-25-2009 at 10:32 AM.
11-24-2009, 10:07 PM
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11-24-2009, 11:59 PM
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notice the color at the top of cylinder one. did the tech say that is normal. and not sure if it is a reflection or something with the picture, but look at cylinder three. looks like scoring in the cylinder. just looked at another pic and seen the score marks in that one also. have them make sure that cylinder is fine
11-25-2009, 12:37 AM
#10
notice the color at the top of cylinder one. did the tech say that is normal. and not sure if it is a reflection or something with the picture, but look at cylinder three. looks like scoring in the cylinder. just looked at another pic and seen the score marks in that one also. have them make sure that cylinder is fine
Warren
11-25-2009, 12:59 AM
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Thread Starter
notice the color at the top of cylinder one. did the tech say that is normal. and not sure if it is a reflection or something with the picture, but look at cylinder three. looks like scoring in the cylinder. just looked at another pic and seen the score marks in that one also. have them make sure that cylinder is fine
Last edited by Stamina; 11-25-2009 at 01:34 AM.
11-25-2009, 01:10 AM
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Nope. They did call me and tell me that the IC they installed ~9months ago, when my stocker's endcap broke, somehow increased power by 60HP though. 
If there was an IC on the market that instantly increased power by 60HP all the time, then count me in. The price Hahn charged for mine would definately be worth it then. 
I think what happened is they were test driving it and accidentally activated the tune while they had the RPD switched to the HP and Torque screen because when I got it back the tune was active and the RPD was switched to that page.
Honestly though, since this was a manufacturing defect, then that shouldn't matter anyway.
If there was an IC on the market that instantly increased power by 60HP all the time, then count me in. The price Hahn charged for mine would definately be worth it then. I think what happened is they were test driving it and accidentally activated the tune while they had the RPD switched to the HP and Torque screen because when I got it back the tune was active and the RPD was switched to that page.
Honestly though, since this was a manufacturing defect, then that shouldn't matter anyway.
Last edited by Stamina; 11-25-2009 at 01:41 AM.
11-25-2009, 01:54 AM
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Man the intake ports look a lot smaller than the other Ecotec heads do. They rounded off the port floor for some reason...... Great pics! The stock turbo is so small and quaint!!
11-25-2009, 02:47 AM
#18
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If your dealer is covering that under warranty I would be a customer for LIFE!!!!!! I would preach there name to every one that needs a new car. The dealer that I use here(moritz chevrolet) seems pretty cool but damn yours is AWESOME.
11-25-2009, 03:13 AM
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i have the same issues and think this may be going on as well. now is it safe to be boosting so much on the car? im hitting 28k on my car, maybe we are the first to see these issues cause all the miles we have put on them with tunes? granted my initial tune was bad, brings up the question of how much should we actually be boosting and pushing these cars? my dealer are fukn dick and never warrenty **** so im sure im getting shafted when i take it in.
11-25-2009, 07:37 AM
#20
Keep an eye out on KR on the RPD, and your oil consumption. Sorry, but #3 is scored. It shows up in every single shot you took. I would suspect the ringlands on 3 are also cracking. It's possible for them to go without knock going up much. A leakdown test will tell the truth. I'd put money that #3 fails a leakdown/comp.
The truth is that no one should be running custom tunes without logging knock sums or knock retard. Without forged pistons, all it takes is 87 octane gas, and an aggressive tune to start a thread like this.
http://en.wikipedia.org/wiki/Hypereutectic_piston
"The biggest drawback of adding silicon to pistons is that the piston becomes more brittle as the ratio of silicon is added. This makes the piston more susceptible to cracking if the engine experiences pre-ignition or detonation."
I came from a Subaru, where that's all people were talking about, and even after laying down over 375 whp and 94k miles, I was paranoid of it happening to me. The LNF is more resilient than that, but it's still hypereutectic pistons in there. At least it's alot easier to rebuild the engine than the oddball boxer arrangement.
Warren
The truth is that no one should be running custom tunes without logging knock sums or knock retard. Without forged pistons, all it takes is 87 octane gas, and an aggressive tune to start a thread like this.
http://en.wikipedia.org/wiki/Hypereutectic_piston
"The biggest drawback of adding silicon to pistons is that the piston becomes more brittle as the ratio of silicon is added. This makes the piston more susceptible to cracking if the engine experiences pre-ignition or detonation."
I came from a Subaru, where that's all people were talking about, and even after laying down over 375 whp and 94k miles, I was paranoid of it happening to me. The LNF is more resilient than that, but it's still hypereutectic pistons in there. At least it's alot easier to rebuild the engine than the oddball boxer arrangement.
Warren
11-25-2009, 08:22 AM
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i sure hope this is not what is happening to my car.. we shall see i guess. i will be doing a compression test this weekend to see where i'm at. thanks for posting the pics!
11-25-2009, 09:58 AM
#22
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Thread Starter
Keep an eye out on KR on the RPD, and your oil consumption. Sorry, but #3 is scored. It shows up in every single shot you took. I would suspect the ringlands on 3 are also cracking. It's possible for them to go without knock going up much. A leakdown test will tell the truth. I'd put money that #3 fails a leakdown/comp.
The truth is that no one should be running custom tunes without logging knock sums or knock retard. Without forged pistons, all it takes is 87 octane gas, and an aggressive tune to start a thread like this.
http://en.wikipedia.org/wiki/Hypereutectic_piston
"The biggest drawback of adding silicon to pistons is that the piston becomes more brittle as the ratio of silicon is added. This makes the piston more susceptible to cracking if the engine experiences pre-ignition or detonation."
I came from a Subaru, where that's all people were talking about, and even after laying down over 375 whp and 94k miles, I was paranoid of it happening to me. The LNF is more resilient than that, but it's still hypereutectic pistons in there. At least it's alot easier to rebuild the engine than the oddball boxer arrangement.
Warren
The truth is that no one should be running custom tunes without logging knock sums or knock retard. Without forged pistons, all it takes is 87 octane gas, and an aggressive tune to start a thread like this.
http://en.wikipedia.org/wiki/Hypereutectic_piston
"The biggest drawback of adding silicon to pistons is that the piston becomes more brittle as the ratio of silicon is added. This makes the piston more susceptible to cracking if the engine experiences pre-ignition or detonation."
I came from a Subaru, where that's all people were talking about, and even after laying down over 375 whp and 94k miles, I was paranoid of it happening to me. The LNF is more resilient than that, but it's still hypereutectic pistons in there. At least it's alot easier to rebuild the engine than the oddball boxer arrangement.
Warren
My RPD has always shown 0* KR in any tune mode to my knowledge, so I don't have much confidence in it unless traditional logging is just picking up phantom knock. The IC looks to really keep the IAT2s down in the logs, so that's promising.
11-25-2009, 10:19 AM
#23
Senior Member
The sad thing is I rarely use the tune. I drive 90-95% in stock tune. A local tuner and I logged the crap out of the tune two times, spending a couple hours each time. I've got logs, but they're pretty much knock-free. I wonder if the stock tune could be the culprit. It seems at partial throttle in some places and WOT stock tunes have been shown to knock sometimes. Maybe we need to poll classic Trifecta tuned people (the ones where it's always on) and see if they've been having any trouble. I may want to go log my stock tune now too as I don't think I've done that.
My RPD has always shown 0* KR in any tune mode to my knowledge, so I don't have much confidence in it unless traditional logging is just picking up phantom knock. The IC looks to really keep the IAT2s down in the logs, so that's promising.
My RPD has always shown 0* KR in any tune mode to my knowledge, so I don't have much confidence in it unless traditional logging is just picking up phantom knock. The IC looks to really keep the IAT2s down in the logs, so that's promising.
