I have an 02 Sierra with 117k. I drive it hard and never had a problem until about 75k. After that on cold mornings my knocks for about 30 seconds and runs perfect. it doesnt burn oil, or at least not enough to add any in the 5k oil change intervals. I cant tell that it lost any power and most people that ride in it says its got alot more power than an identical truck. i have owned it since new, the only thing i done was add a cold air kit. So how can you determine if it is piston slap, or the lifters bleeding off over night. i dont notice the knock if the engine sits for only a couple hours, but typically at least 8 hours.

 

was shiftin at 65hundred. is that bad? felt good when i was doin it . :-)

 

mechanically what causes this? piston/ring/cylinder wall/valve train......i know its nothing serious, but i would like to know what causes it in these motors

 

When ever my car is cold started it runs for about 10-15 seconds and then it taps/slaps for about 20-30 seconds and then it stops making the noise ... I assume it piston slap becasue the oil pressure is close to 60 psi and it has very little stuff on the magnetic drain plug at oil changes..it has made this noise at cold start now for the last 100,000 miles .. it runs great and uses a half quart of oil every 2500 miles...it has 145,000 miles on it now ... runs strong and sees the red line every day..

 

Got some lifter noise but its pretty loud in the morning for about 3 minutes till it warms up. Got 186563 on the clock and still hit 6k RPM on an everyday and usual basis as I'm getting on the highway or racing some punk kid. No rebuild yet, just bolt ons.
Goes through a quart of oil about every 900 miles.

 

Enough results, you get the idea. This issue has even been to court and back.
Closed