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LSA engine smoked and scratch behind flexplate

Old 01-06-2019, 02:42 PM
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Default LSA engine smoked and scratch behind flexplate

So i was at a roll race event with my newly tuned 2013 CTS-V, the car was running fine and with no issues, at the first race in the event at 4th gear the boost dropped from 15 psi to 9 psi and smoked. When i stopped there was an oil leak. The car drove fine and everything. When the engine was pulled out pistons 4 and 6 were damaged. But there was a scratch at the back of the block behind the flex plate. The block looks fine except for the scratch behind flex plate. Can i just grind it off and reuse the block?

Thank you

Last edited by LS1TA76; 01-07-2019 at 01:24 AM.
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Old 01-06-2019, 08:18 PM
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That's also behind the rear cover. There must have been some foreign object get caught between the crank and the block. The engine builder didn't find anything in the else in the tear down? Could be something simple like a washer. Are all rocker arm needle bearings accounted for? That rear main bearing isn't looking so hot either.
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Old 01-07-2019, 01:22 AM
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who cares about the mark, I'd be more concerned about the bearings. you see the first one the second is fuzzy but you can still see the same marks, did the builder check the crank thrust?
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Old 01-07-2019, 01:27 AM
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Originally Posted by 96 Comp T/A View Post
That's also behind the rear cover. There must have been some foreign object get caught between the crank and the block. The engine builder didn't find anything in the else in the tear down? Could be something simple like a washer. Are all rocker arm needle bearings accounted for? That rear main bearing isn't looking so hot either.
just edited the thread, 2 pistons were damaged. But block looked totally fine except for the scratch. Can i reuse the block?
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Old 01-07-2019, 01:30 AM
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Originally Posted by cmysix View Post
who cares about the mark, I'd be more concerned about the bearings. you see the first one the second is fuzzy but you can still see the same marks, did the builder check the crank thrust?
Crank thrust is flawless. Nothing on it. My main concern is if i can reuse the block or not
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Old 01-07-2019, 03:07 AM
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That area needs to be dressed but Yes, You could reuse the block.
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Old 01-07-2019, 06:05 AM
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Originally Posted by 1FastBrick View Post
That area needs to be dressed but Yes, You could reuse the block.
I agree about the block, but I don't know your engine builder from Adam, but those bearings are just wrong, did he plasta gauge the crank bearing clearances ?
?
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Old 01-07-2019, 08:20 AM
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Originally Posted by cmysix View Post
I agree about the block, but I don't know your engine builder from Adam, but those bearings are just wrong, did he plasta gauge the crank bearing clearances ?
?
Those are stock bearings so it’s probably still the stock shortblock. Besides, it doesn’t look like damage from too tight of clearance. It looks like damage typical of when debris makes its way through the engine.

I would clean up the gouge and reuse the block. Probably wouldn’t be a bad dea to check for cracks in that area either.
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Old 01-07-2019, 08:46 PM
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Sooo... what caused damage to the pistons? Might want to look at that new tune before firing the engine up after the rebuild.
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