04 Denali rattle can sound around 800-1200 rpms

[DenaliJJ]

I will contact blackstone. Might need to wait till next change because it's in a container with the 302s oil now. Anyone else want to go with piston slap? I would be totally with the noise if all it was piston slap haha. I have great oil pressure now runs good and no codes in the system.

 

[HiHoeSilver]

My thoughts too. Funny thing is I can't hear it when someone revs it up past 1200 though. You would think somethin motor related would be louder through Rpms right? What's the easiest way to check the flexplate?

You can see it through the inspection window, just pop the cover off and look in there with a good flashlight.

 

[DenaliJJ]

You can see it through the inspection window, just pop the cover off and look in there with a good flashlight.

Thank you for the reply. What will I be looking for exactly?

 

[HiHoeSilver]

Cracks or missing teeth, etc. You may need to turn the engine over with a big ratchet to spin it around as you can only see so much through the inspection hole.

 

[DenaliJJ]

Sounds good. Thanks Does this sound like a piston slap lifter or flywheel noise to you?

 

[HiHoeSilver]

So hard to say from videos. Have you tried a stethoscope at all?

 

[DenaliJJ]

So hard to say from videos. Have you tried a stethoscope at all?

Will poke around with a scope today. My neighbor is a gm mechanic at our local dealer and he said it sounds like lifter as his does the same sound and his been doing it for around 70k. Also told me if it backfires then that's not good and pulling the heads and intake is in order to fix it. Book calls for about 8 hours but said could realistically be done in about half that

 

[DenaliJJ]

Figure I'll give an update on the matter. Today I took it out for a spin and since I've never really hammered on it I decided what the hell amd so I took it to about 50 at wot. Oil pressure hit a tad over 60psi and I continued to the gas station. let it sit at home for a few hours and started it up and the noise barely lasts 30secs now and isn't nearly as loud. Maybe the wot cleared some gunk up??

 

[recycleoldgrowth]

My last two suburbans sound just lake that, to me it's good old piston slap. Sounds like crap but clears up quick and I've been told by many sources that it doesn't harm the motor (I personally have a hard time believing that but my first suburban I sold at 300k and was running like a champ)

Sent from my SM-G530T using Tapatalk

 

[DenaliJJ]

My last two suburbans sound just lake that, to me it's good old piston slap. Sounds like crap but clears up quick and I've been told by many sources that it doesn't harm the motor (I personally have a hard time believing that but my first suburban I sold at 300k and was running like a champ)

Sent from my SM-G530T using Tapatalk

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

 

[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.


Sent from iPhone 7 plus using Tapatalk Pro

 

[DenaliJJ]

Its a cat.


Sent from iPhone 7 plus using Tapatalk Pro

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.


Sent from iPhone 7 plus using Tapatalk Pro

 

[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.