2000 5.3 got any ideas?It is still under warrenty

 

Unfortunatly, you don't have many options on what to do about it. GM has protected themselves pretty good from this by claiming it is normal. The best thing I can suggest is to start taking it to dealers. How long does it last? I have not had this problen YET but the guys that have can probably add to this.

 

it last 20-30 seconds and is worse under acceleration

 

Does it go away after the engine reaches temp? There are other things it can be doing also. Not all the motors are immuned to just breaking internally, IE: lifters, valves, rods, pushrods etc...What you discribe is looking like a classic case of piston slap and cold start knock. Again, I would take it to a dealer and if your not satisfied with the answer they give, go to the next one. Some dealers are more sympathetic to this problem than others.

 

mine doesnt go away after it reaches operating temp, sitting idleing where its quiet you can hear it real good, sounds like crap

 

It sucks!!$30,000 and it sounds like a '78 pickup truck.What is really sad is that a GM is still better than anything else out there.Don't get me wrong I love my truck but,I wish they would do someting about the noise because it is very common. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />

 

I'm with "really slow truck" the noise in my truck is present at idle (not very loud) and when I accelerate (much louder). This knocking noise has always been present in my truck and people have told me it's common LS1 lifter noise. I think it's common, a common GM manufacturing screw up. I think GM just f**ked us to some extent. <img border="0" title="" alt="[Mad]" src="gr_images/icons/mad.gif" /> Here a link that I found in one of the other forums and I'm not sure who has signed it, but I did. One voice maybe lost in the noise (no pun intended), but all of us might be able to make a difference.

http://emer.homedns.org/ls1_knock/index.asp
Let's give them hell!!! <img border="0" alt="[guns]" title="" src="graemlins/gr_guns.gif" />

Don’t get me wrong I love my tuck, but I paid for a better engine in opinion.

 

First lets isolate the problem before jumping to the cold start knock issue.

Is it a knocking? Or is it a buzzing?

 

Check out http://www.angelfire.com/tx5/gmpistonslap/index.html. This website has an audio clip of what piston slap sounds like.

 

I know I shouldn't jump to any conclusions, but the knocking noise (not cold start) was getting to me on 610 on my way to school the other day. <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />