Intermittent clacking noise

[Rexxrally]

2005 Yukon 5.3 engine.
When cold, engine runs and sounds just fine.
Once it's warmed up, and left to idle for 5 minutes or so, it starts making a clacking noise. It's quite noticeable when the Yukon is beside a building (like in a drive-thru line). If I rev it up, the clacking noise increases with the speed of the engine.
If I drive it after that, the clacking noise will go away after a few minutes.
The whole time, even while clacking, the engine runs perfectly (full power, no hesitation, no Check Engine Light, no codes thrown).
Has anybody had this before, can give me an idea of what it could be?

Thanks!

 

[DenaliJJ]

What’s the oil pressure at when this noise comes and goes?

 

[Rexxrally]

What’s the oil pressure at when this noise comes and goes?

The oil pressure reads normal and everything else on the dashboard is normal, too

 

[Rocket Man]

What's normal? 40 at idle and 50-60 at higher rpm's is considered normal for the 2000-2006's. It's different for the 2007-2014's which usually sit at 20 idle. So if you're seeing 40 at idle then it is normal for your year.

 

[Rexxrally]

Well, being Canadian, our gauges have a different scale. Mine shows 250 in the middle of the oil pressure gauge. While driving, the needle points just right of the 250. While idling, it points just left of the 250.

What's normal? 40 at idle and 50-60 at higher rpm's is considered normal for the 2000-2006's. It's different for the 2007-2014's which usually sit at 20 idle. So if you're seeing 40 at idle then it is normal for your year.

 

[Rocket Man]

Sounds normal then; on mine 40 is in the middle, straight up. I'm thinking it sounds like you have lifter noise or piston slap but I'd be more inclined to go with lifter noise. We need to hear it- can you do a YouTube video?

 

[Rexxrally]

Here's my video of me in the drive thru line.

Sounds normal then; on mine 40 is in the middle, straight up. I'm thinking it sounds like you have lifter noise or piston slap but I'd be more inclined to go with lifter noise. We need to hear it- can you do a YouTube video?

 

[SirReal63]

If you haven’t done a motor flush, I would. The oil galleries in the lifters are small and can get clogged easily. It is fairly common and easily rectified. If a good flush doesn’t fix it you may be pulling heads.

 

[Rocket Man]

I can't tell for sure, but that doesn't sound like lifters to me. Maybe try using a stethoscope or the old trick of holding a big screwdriver or something to your ear while putting the other end on various areas of the engine to pinpoint where it's coming from. Kind of sounds like a pulley.

 

[M1Gunner]

I can tell you 100% that is not anything related to lifters.

Is that with your A/C on?