04 Denali rattle can sound around 800-1200 rpms

[DenaliJJ]

hey guys. New to the forum here and this is my first post. I recently purchased a 04 Denali xl that needed a fuel pump. So I replaced it with a Delphi and all is well there. Had an issue with a whirling noise heard at idle so I loosened belt and spun the stationary idler. Replaced and all is well. Now I have this noise at start up that sort of sounds like a ball bouncing around in a can for around 20 secs at idle. Seems to fluctuate in pitch and rythem if that makes any sense. After a bit it goes away. When I lightly touch the gas pedal I get to around 800 rpm and it starts the vibrating rattle clanking noise up to around 1200 and then i can't hear it until I let off gas and it gets back down to 800 for and dissapears after it's back down Around 5-600 rpm. I'm left thinking it's either the tensioner vibrating or possibly flywheel cracked. The reason I think it's not inside the motor is because I can hold the gas to where it starts making noise and it variates while holding steady at right around 1000 rpm. Oil pressure is right around 40 at start up and after a good hour or so of running it's anywhere from around 20-25 at idle in gear. Any ideas where to start? Sorry for lengthy post but I wanted to be as thorough as possible. Thanks in advance!

 

[Danny3737]

Can you post a video with the sound?

 

[Fless]

Might want to check the cat shields to make sure they're not loose. Those things can make some racket at various RPMs!

 

[DenaliJJ]

Yes I will try and upload a video here yet tonight via YouTube

 

[DenaliJJ]

Went to check the heat sheild and and there isn't anything around either one

 

[DenaliJJ]

 

[DenaliJJ]

With this noise it's not as evident in early morning start ups. After it warms out side or engine runs awhile it's heard on start up worse( short video) any ideas where to start or hell maybe it's an exhaust leak. I'm stumped

 

[06Escalade]

I had a similar issue recently. It was broken catalyst rattling around inside the y pipe. Depending on how much exhaust was passing through the pipe I would hear it. Enough "wind" to make that chunk of catalyst rattle around I guess. I won't be playing with additives like Seafoam ever again.

 

[06Escalade]

Replacing that catalyst y pipe was an amazing difference in the performance of the truck. Breathing out gives better gains than breathing in, thats for sure.

 

[DenaliJJ]

Replacing that catalyst y pipe was an amazing difference in the performance of the truck. Breathing out gives better gains than breathing in, thats for sure.

Where you able to hear anything when you smacked the pipes?