Detonation and misfire problem ??
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Originally Posted by kidturbo
So consensus is there is no difference in the long block portion of the 3800 SC or not? Just want to make sure before I put down the cash for a replacement.
The lower ends will interchange, but the non-SC lower end will not last nearly as long under boost applications (at least not with higher boost of 8-9+).
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Originally Posted by OLBlueEyesBonne
Originally Posted by kidturbo
So consensus is there is no difference in the long block portion of the 3800 SC or not? Just want to make sure before I put down the cash for a replacement.
Cheers.
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Update: I only spent a couple hours doing diag on this while home last week but here is what I found. Started it up and the knock was still there, cylinder 3 was not firing at all. Checked valve train, pushrods springs looked fine, sounded like a rod so we dropped the pan and checked all of them, no problems. Cylinder 3 sparkplug gap was closed off, the GM dealer had just changed them 20 miles earlier. Brought that piston to the top and took a look inside with a mirror. Many ding marks on the top of the piston, that was enough for me to call it quits for the week until I get time to tear it down.
Has any of you leaned out enough to burn a piston??
Still looking for the root cause of the over boost but I can only conclude that the cat failed and is restricting the exhaust to the point that the SC overfilled the engine and caused it to go lean burning a piston. Unless anyone has a better conclusion, I won't be 100 % until I pull the heads next week now.
Has any of you leaned out enough to burn a piston??
Still looking for the root cause of the over boost but I can only conclude that the cat failed and is restricting the exhaust to the point that the SC overfilled the engine and caused it to go lean burning a piston. Unless anyone has a better conclusion, I won't be 100 % until I pull the heads next week now.
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Chipping a piston (most lovingly refer to it as "chunking") happens fairly frequently in the GP community. The piston goes lean, detonation chips a piece off and the piece flys into the cylinder usually hitting the spark plug leaving a telltale sign (gap closed, broken, etc..). Most of the time this happens when people mod incorrectly by not using supporting mods, or running the motor with large amounts of KR.
If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
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Originally Posted by Rogue
Chipping a piston (most lovingly refer to it as "chunking") happens fairly frequently in the GP community. The piston goes lean, detonation chips a piece off and the piece flys into the cylinder usually hitting the spark plug leaving a telltale sign (gap closed, broken, etc..). Most of the time this happens when people mod incorrectly by not using supporting mods, or running the motor with large amounts of KR.
If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
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Originally Posted by LakevilleSSEi
Originally Posted by Rogue
Chipping a piston (most lovingly refer to it as "chunking") happens fairly frequently in the GP community. The piston goes lean, detonation chips a piece off and the piece flys into the cylinder usually hitting the spark plug leaving a telltale sign (gap closed, broken, etc..). Most of the time this happens when people mod incorrectly by not using supporting mods, or running the motor with large amounts of KR.
If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
I've known a few people who just changed the plug and went on with things but continued to be hard on it and eventually the piston failed entirely.
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Thanks guys, I feel better already
I actually called the GM dealer and gave the service mgr heck for letting an amateur work on it. Said he must have dropped the plug and never gaped it again, then after we pulled the pan to check the rods and could find nothing wrong I started thinking
Maybe I should go back up top and take another look at that plug, closer inspection showed some small specks of aluminum welded to the back side of the electrode. That made me feel bad and had to call him up and beg for forgiveness.. But they were driving it when it chunked the piston so I think we're even.
The only good things are the cylnder wall looks ok from the bottom side, and the pan is still off so getting the piston out should take less work from here.
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I actually called the GM dealer and gave the service mgr heck for letting an amateur work on it. Said he must have dropped the plug and never gaped it again, then after we pulled the pan to check the rods and could find nothing wrong I started thinking
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The only good things are the cylnder wall looks ok from the bottom side, and the pan is still off so getting the piston out should take less work from here.
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Originally Posted by kidturbo
The only good things are the cylnder wall looks ok from the bottom side, and the pan is still off so getting the piston out should take less work from here.
But that'* not to say I'm right -I've been wrong before.
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Originally Posted by OLBlueEyesBonne
Originally Posted by kidturbo
The only good things are the cylnder wall looks ok from the bottom side, and the pan is still off so getting the piston out should take less work from here.
But that'* not to say I'm right -I've been wrong before.
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