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2002 LS1 (used) knocks on first startup

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Old Aug 18, 2011 | 09:25 PM
  #1  
DerrenC's Avatar
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From: Portland, Oregon
Default 2002 LS1 (used) knocks on first startup

I'm trying to resolve a knock in my engine. I've been getting help from members at TGO in this thread:

http://www.thirdgen.org/techboard/lt...ns-knocks.html

but maybe my questions more appropriately belong here.

That thread chronicles how it sounded wrong when it first fired:



and how I ended up pulling the heads (after pulling the pan and checking rod bearings) to find this:



The rings looks to be intact, and there is a wide shallow gouge on the cylinder wall opposite the piston damage. Valves appear fine.

So my question for experienced LS1 owners is this: As bad as that looks, would it cause the knock heard in the video?
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Old Aug 18, 2011 | 11:28 PM
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It more than likely has something broken in the valvetrain. Sounds just like my buddys car when a rocker lost all the needle bearings.

All the cars I have seen lose a ringland have ran decent -1 cylinder. My friend drove his car 70 miles home from the track with a broken ringland. Other than a slight miss and a back fire it ran as quiet as before.
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Old Aug 19, 2011 | 08:52 AM
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So far the valvetrain looks fine. I pulled the rockers and pushrods and they were fine. I pulled the heads off to replace the lifters when I found the busted piston.

I figured I had found my problem, but yeah, I wondered if it would actually cause a knocking noise or not.

Has anyone ever had a busted piston like this cause a discernible knock from the engine?
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