I've heard about this on other boards but what is the difference between the two? I have an '01 4.8L and on start-up I have a pretty noticeable tapping sound for about 5-10 minutes and then it gets less noticeable (still there but pretty quiet). I only have 10,600 miles on my truck and I only use Union 76 89 or 91 octane gas.

Does this noise sound familiar to any of you guys? Is it the sign of a SERIOUS problem or not? I've heard a lot of people worried about problems because of this noise but have yet to hear from people that they've had major problems because of it.

When I get a chance I'll have to record (with my laptop) a quick sound clip of the noise my truck makes. This will probably help some you understand what I'm talking about.

 

I'd like to hear the sound. I could compare it to my 99 with 60K+ miles. I have almost the same symptoms with not known problems at this time. My exhaust is loud enough that I don't hear the noise most of the time. GM would probably say its normal.

 

Damn it!!! I can't record the sound because my computer microphone is too sensitive. It sounds like crap. Oh well, I'll tinker with it and see what I can come up with.

Anyway what is the difference between piston slap/engine knock? Are they the same thing?

 

i have an 02 6.0 and have been told by some that the 6.0's are worse than most for piston slap. i have a definate cold engine tap, for about 5-10sec. seems like i have another sound that lasts longer or might even be there all the time, sounds more like a slight knock rather than the cold tapping. i am not going to worry about either, if she blows than it will be a good time for an 409-415ci <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> i have heard this sound on other trucks also, sounds like a faint rod noise to me, the kind of sound that if it was a rod and you reved it it would turn into a hammering sound but this doesn't

seems like i have heard if you take your truck in a few times for the knock that chevy may extend the warrenty on your engine to make you happy. it is prety hard to get them to swap out the engine though.

 

Yeah my 5.3 is doing it. It's done it since 1500 miles or so. From what I can tell the pistons shrink and swell and make this noise until they get good and hot. Then it should go away.

 

I got a 2002 2500HD with a 6.0 in it a few months ago and it is pretty loud on start up, its really loud on a cold morning. I am taking it in tomorrow I will let you know what they say.

Sean

 

My '01 4.8L has a similar noise to the "slapping" or "tapping" noises that everyone describes as piston slap, but my noise is NOT at startup, and doesn't go away. The dealer associated it with the cold-start noises and dismissed it saying that nothing needed to be done to fix it and that it had no affect on reliability or longevity of the motor. I still think it's funny that GM coats the pistons now to make them quieter. I'd like to get a set of those pistons and see if my noise just disappears.