Tapping.. How worried should I be?

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destroyer1362

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So I noticed my yukon making a tapping sound, like tapping a pen on a desk, when I start it up. After about 10-15 seconds the tapping gets so quiet I would have to stick my head in the wheel well to hear it. I can live with that though. What's bothering me is the tapping sound comes back when the motor is under load during normal acceleration or just a quick rev to 3000. It was tuned up less then 500 miles ago. Also I have narrowed the sound down to the number 8 cyl. When I listen to the exhaust I hear a good "thump thump" sound, but sometimes every couple of seconds I hear a sloppy exhaust note. I know that sounds dumb but thats the only way I could describe it.

Please tell me I don't need new lifters. Or does this sound like a sticky valve that could be easily fixed?
 

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DJTricky

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do an oil change, all it is is piston slap, it usually will happen when you start up a cold motor, could also be a sticky lifter or valve,
 
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destroyer1362

destroyer1362

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What year is it? I've heard quite a few 5.7s do this at start up, but never while driving.

It's a 2000 Denali 5.7

---------- Post added at 04:06 PM ---------- Previous post was at 04:02 PM ----------

do an oil change, all it is is piston slap, it usually will happen when you start up a cold motor, could also be a sticky lifter or valve,

will do.. Do you think I should try seafoaming as well?
 
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