everytime i start my truck, it sounds like there is lack of oil in the valve train and there is a clicking sound for about 10-20 seconds. then it goes away. is this normal for the 5.3 liters?

 

do a search for "piston slap" im pretty sure that's what's happening with yours

 

Ya I have the same thing and from what im told its very common.

 

with an aluminum block and no cats it sounds like you have a midget clapping under your hood. it only gets better during the winter time hahaha. it is kinda embarrising at times though.

 

it could be the roller rockers, it will be more of a tapping sound, this is common on these trucks even when they are new. it will usually be worse if the truck has not been started for some time

 

its lifter tick and very common. seafoam and different weight oil sometimes help.

 

There's actually a bulletin from GM about this. I've covered it and posted it about4 times on here but it explains the lifter tick that you hear. GM calls it the nature of the beast but Torque Wrench calls it "bullshit"...lol

 

I have a little bit of a lifter tap...sometimes it sounds like theres something wrong but it runs awesome.