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knock and scrape

Old Oct 11, 2007 | 08:32 AM
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Default knock and scrape

Hello all. Longtime gen 1 guy here, years on IrocZone and TGO, first time dealing with an LSx...


Anyway, my buddy picked up a 1998 T/A awhile back and we've been toying with it for some time now. Recently it just got really really cold out. Last night we were cruising as usual, everythings fine. I guess this morning on his way to school, he starts to hear a knock and scrape. He called and I thought it would just be the typical LS1 piston slap since it is cold out, but he said the engine was fully warmed.

He says it doesnt happen all the time though and it does kind of drop oil pressure and vary in RPM's. The engine does has about 112k on it, we ofcourse dont want to think about rod knock or oil pump failure, but what do you guys suggest?
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Old Oct 11, 2007 | 08:41 AM
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Sounds like rod bearings, not good and very common on 98s
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Old Oct 11, 2007 | 08:45 AM
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I have a 98,and just like pred said its common on 98's. I replaced my rod bolts with Katechs and clevite bearings,just in case
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Old Oct 11, 2007 | 08:47 AM
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So, if it hasnt chwed up the crank and such already, it is possible to just replace the bearings and have no machine work done? or is it a must to also have the crank turned down and oversized bearings put in place? For the rod bolts, those will need to be pressed in/out correct?


thanks for the quick replies guys
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Old Oct 11, 2007 | 08:50 AM
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It would require rebuilt of shortblock, all else is a band aid
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Old Oct 11, 2007 | 08:54 AM
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Why is it common with the 98's? I heard the first batch of LS1's, like 98-00 were built tighter and oiling problems and such.
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Old Oct 11, 2007 | 09:25 AM
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I did not have any knock or scrape. I added the katechs to avoid this. If I did have a knock or scrape as you are describing I would have done a rebuild
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Old Oct 11, 2007 | 09:48 AM
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What about the possibilities of other things that I have read up on here such as pushrod issues and loose rocker? Should we check those first before we yank the motor out?
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Old Oct 11, 2007 | 09:55 AM
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Typically a valvetrain noise is at half the speed of the engine and a piston/rod problem is 2x faster than a valvetrain noise. If it's a slow tick it's valvetrain. If it's fast, bottom end.
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Old Oct 11, 2007 | 09:59 AM
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Anybody have a complete bottom end rebuild list?

better yet, any of the sponsers sell shortblocks? Links?

looks like this is golden.. ..

http://www.sdparts.com/product/SDLS6...kAssembly.aspx

Now, anybody sell a complete gasket kit?

Last edited by CTC B4Z; Oct 11, 2007 at 10:40 AM.
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