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Knocking on startup

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Old Jan 29, 2007 | 07:26 PM
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red99formula's Avatar
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From: Frederica, DE
Default Knocking on startup

Lately I've been hearing a knocking sound on start up that only lasts for about 30 seconds or so while the engine warms up. Does anybody else have this problem? If so what is it and how do I go about fixing it?

Last edited by red99formula; Jan 30, 2007 at 09:46 AM.
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Old Jan 29, 2007 | 07:47 PM
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From: Leon, IA
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time for some new pistons sounds like
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Old Jan 29, 2007 | 07:54 PM
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Originally Posted by red99formula
Lately I've been hearing a knocking sound on start up that only lasts for several minutes while the engine warms up. Does anybody else have this problem? If so what is it and how do I go about fixing it?
I'm guessing by the post count that you recently purchased the car? LS1s have a piston slap characterized by starting a little after it is first started cold and lasting about 30 seconds to one minute. It is caused by the short piston skirt, piston size etc. but will do no harm. If it knocks after it starts to warm up it's something different and we'll need further info.
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Old Jan 29, 2007 | 08:28 PM
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piston slap, ftl
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Old Jan 29, 2007 | 11:51 PM
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It's cold out side, it's a GM product, get used to it. It sounds like what you are hearing is someting that every LS based engine encounters on start up with a cold motor.
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Old Jan 30, 2007 | 09:44 AM
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From: Frederica, DE
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Hey thanks, yeah I did just get the car about a month ago and I already have big plans for it, anyways it has been really cold here in delaware as of late if that makes any difference. It doesn't do it all the time on start up but when it does, it's always cold and it only goes for about 30 seconds or less.
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