04 Denali rattle can sound around 800-1200 rpms

[kwOH]

I'm hoping that's all it's. Motor runs great and other than the embarrassing sound at start up I love it. Always been a Ford guy but now I'm lookin at a newer Yukon for the wife and kids

Its a cat.


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[DenaliJJ]

Its a cat.


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I've tried tapping the pipe and listening to right below the cats and don't seem to hear the noise

 

[kwOH]

I've tried tapping the pipe and listening to right below the cats and don't seem to hear the noise

My 05 did the same thing, never heard anything unless I was going up a hill.


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[about20ninj45]

Had a similar issue. Mine was the cat which gutted itself and the noise went away

 

[Contend997]

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!

 

[Contend997]

Check your heat shields it sounds like a shield has come loose and thats where your getting your rattle

 

[DenaliJJ]

I'll go check again after it's done raining and see if I can find somethin loose. I swear it sounds motor related now

 

[Danny3737]

The best way to diagnose it is with a stethoscope.

 

[swathdiver]

Take a long extension and using it as a stethescope touch one end to various items you suspect the other end to your ear. You'll find out in a jiffy.