Bought this 2011 Silverado 5.3 ecrb has 3000 miles and the damn thing is already knocking.
Bought as haul truck for race car. Dealer told me today this is not an abnormal noise. Anyone else with a "stock" truck have this problem.

 

no knock here...14k on the clock already.

 

You talkin about piston slap?In other words knock upon startup.That is very common with 5.3's in general.Im not sure if its in the pcm programing but,regardless its a annoying quirk that Gm seems to careless about addressing.

 

ive never heard this?

can you explain some more of this?

 

Its basically a knock or detenation sound at startup that happens a split second after the truck fires.I have not had the joy of owning a truck that does it.Deffinately heard of trucks do it plenty of times.

 

I think it is piston slap. But I thought GM addressed this issue in the early 2000's?
Takes a few seconds at start up to start the knock. But it seems to only make noise at idle. Raise the RPM's by as little as 150 to 200 and it goes away. The truck also surges in time with the noise when creeping with the brakes applied such as in rush hour traffic. Especially with trailer loaded. Humiliating pulling into the pits at the track. People do notice and ask "do you know your truck is knocking?"
I haven't found any TSB's. Seems I just bought a $27K knock!

 

For anyone wondering what this sounds like, search "Silverado piston slap" on YouTube. Unfortunately, there are a lot of videos of this on there.

 

i have worked at gm dealer for a while. my 02 silverado 5.3 does it cold. so does my 01 trans am. trans am worse. it goes away after 3 to 5 min an it okay. i realy thought gm would have fixed this prob by 2011. well thats gm for you the never fix there mistakes. just like fuel level sensors. that why i dont by new gms anymore just not worth it. if your noise goes away after 3 min i wouldend worry that bad. what the real problems with new trucks are cam and lifters lifter takes out cam usually 7 8 cyl. what i would do in this situation is cheange your oil at the intervals that realy help with these engunes alot.

 

Like SincalT/A said, very common.

I too thought they addressed it, like said early 2000's. I'm actually surprised to even hear of this on an '11. IN part cause I thought it was cured, & cause the truck I own or my bros. had / have, no cold slap.

I believe by extending the piston skirt down, but they may've put a coating on the skirt. It was along those lines.

 

I would guess either piston slap or your lifters are shitting out.