Tapping.. How worried should I be?

[destroyer1362]

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?

[BOSS]

Not sure but I bet you can find.....OH, WAIT! You're already here :D



BOSS

[road1will]

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

[DJTricky]

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,

[destroyer1362]

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?

[DJTricky]

i would give it a shot, my hor ran alot better after i did,

[blueflamed03]

mine sounds like a sewing machine, normal piston slap.