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Camaro V8 LS3 / L99 Engine, Exhaust, and Bolt-Ons Bolt-Ons | Intakes | Exhaust

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Old 05-13-2010, 09:15 AM   #1
Bowtie Junkman
 
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Chatter at start up ...

Hey guys (and gals) ...

Anyone else getting that chatter (sounds like coming from the valvetrain) for 1-2 seconds at start-up when cold?

I've had (2) other vehicles with LS2's (C6 and TBSS) and I seem to remember them doing the same thing ... but I thought it got better as time went on ... I'm at 2500 miles now and I think it's gotten better, but definitely still there ...

I thought I remembered someone stating at one time on the Corvette forum it had to do with the LS motors having floating wrist pins ... ???

Anyone else experiencing this and anyone with the explanation?

Thanks!
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Old 05-13-2010, 10:12 AM   #2
trudawg660

 
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i hear it too, everybody keeps saying it is normal
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Old 05-13-2010, 10:42 AM   #3
Dave2SSRS
 
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I have it as well... assumed it is normal
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Old 05-13-2010, 10:52 AM   #4
Russell James


 
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It's the lifters that bled down.

At shut off, some valves are open = valve spring pressure against the lifter. After so much time, that lifter may bleed off it's oil. Then at start, those couple lifters that bled down go tap tap tap for a few seconds until they get oil pressure.

Plus every lifter to lifter bore fit might be a hair different. If the engine just happens to stop with a lifter up on the cam lobe that has a hair looser fit, over a day or two that one may bleed down. Whereas a real tight lifter might sit up on the cam for weeks without bleeding down.

Harley's do the exact same thing, and they use SBC roller lifters too. Every once in a while an HD will be a biotch to start because one or more of the valves isn't opening much due to the lifter bleed down. With only two cylinders its a much bigger problem when one of the valves decides not to open while cranking.

All the LS engines I've had over the year do it, so I wouldn't sweat it. Even my 5.3 truck engines have done it, and they use lighter valve spring pressure.
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Old 05-13-2010, 10:55 AM   #5
ron10


 
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mine does it also.usually when it has set for a couple of days.if the car is still warm,it does not do it.
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Old 05-13-2010, 01:49 PM   #6
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My car has done it since it was a couple of weeks old. I read the threads on here and wasn't very concerned, but took it to the dealer anyway. They couldn't recreate the problem, so I eventually took some video and e-mailed it to them. The technician said nothing to worry about, but they were going to have the service manager and GM rep. listen to it and get back with me. That was about 2 weeks ago. Still waiting.
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Old 05-13-2010, 02:29 PM   #7
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Piston slap? My LS2 does it when cold, as does the LS3
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