Drone Rattle @ 1400rpm Stock Exhaust

[Plainsman]

I was having noise with my cats and those are now replaced but I now hear a drone about 1400rpm with no load. It sounds right under the middle of the bed its very irritating. The entire exhaust is all new its a 2003 1500HD with 60,000 miles. It only seems to make this noise when warmed up. I read one post about the drive shafts making a drone vibration being hollow aluminum, could that be the case? Id think the issue to be simpler with just some shield vibrating against the cabin. I cant seem to find anything under the truck and just revving the engine will not reproduce the issue. From a stop sign accelorating slowly to around 25 you hear it pass though that droning range, you can also slow and drop right into the area and make it resonate as well.

 

Thoughts?

[RJG183SA]

I was having noise with my cats and those are now replaced but I now hear a drone about 1400rpm with no load. It sounds right under the middle of the bed its very irritating. The entire exhaust is all new its a 2003 1500HD with 60,000 miles. It only seems to make this noise when warmed up. I read one post about the drive shafts making a drone vibration being hollow aluminum, could that be the case? Id think the issue to be simpler with just some shield vibrating against the cabin. I cant seem to find anything under the truck and just revving the engine will not reproduce the issue. From a stop sign accelorating slowly to around 44 you hear it pass though that droning range, you can also slow and drop right into the area and make it resonate as well.

 

Thoughts?

 

Is the "new" exhaust a factory replacement or aftermarket? The 6.0 engine is known to produce a drone in the cab right around the rpm you describe with some aftermarket systems.

[vucelick]

Mine did something similar, especially with the A/C on. It was the heat shield on the muffler. I took it to a muffler shop and most of the tack welds on the shield were cracked or broken thru.

[Plainsman]

I was having noise with my cats and those are now replaced but I now hear a drone about 1400rpm with no load. It sounds right under the middle of the bed its very irritating. The entire exhaust is all new its a 2003 1500HD with 60,000 miles. It only seems to make this noise when warmed up. I read one post about the drive shafts making a drone vibration being hollow aluminum, could that be the case? Id think the issue to be simpler with just some shield vibrating against the cabin. I cant seem to find anything under the truck and just revving the engine will not reproduce the issue. From a stop sign accelorating slowly to around 44 you hear it pass though that droning range, you can also slow and drop right into the area and make it resonate as well.

 

Thoughts?

 

Is the "new" exhaust a factory replacement or aftermarket? The 6.0 engine is known to produce a drone in the cab right around the rpm you describe with some aftermarket systems.

 

 

 

The exhaust is all straight from the bowtie boys. All oem.

[vucelick]

The exhaust is all straight from the bowtie boys. All oem.

 

 

 

 

Mine is completely stock as well, check that muffler heat shield, mine barely moved but it droned exactly like you described, once the tack welds were repaired, I was amazed at how much noise I had gotten used to hearing, it was nearly silent!

[cbxeric]

GM has a fix, there is a steel band that re-attaches the heat shield and stops the drone. There's a TSB on it so I guess it's a common problem.

[steiny93]

GM has a fix, there is a steel band that re-attaches the heat shield and stops the drone. There's a TSB on it so I guess it's a common problem.

 

you have tsb number?

[Plainsman]

GM has a fix, there is a steel band that re-attaches the heat shield and stops the drone. There's a TSB on it so I guess it's a common problem.

 

I placed 2 ss pipe clamps around the heatshild and muffler, seemed to have no effect. The new muffler also looks different than the old, it has 3 bands around it already I wonder if its a new design since 03. I looked at the tranny shield it was all tight and not touching. Everything else looks fine under there.

 

I wish I could see somthing hanging loose or cracked. Anymore thoughts?

 

*Update*

I played with the noise and cant repro when in neutral but I can repro when in gear with the brakes on and taking the RPM to 1400. That seems to indicate not an axel-drive shaft issue plus now I can have a helper isolate where the noise is origionating.

 

The other option was to get somone like SnakeEyes dragging underneath the truck

[Plainsman]

I got the opportunity to crawl under the truck with my buddy power braking it @ 1400. Its the entire exhaust system resonating. I couldnt stop it with just my hand on the muffler, it took a foot on the muffler and a hand on the cat.

 

My idea was to heat up the system (drive around) loosen the clamps, get it vibrating again, then retighten them.

 

Any other ideas?

[cbxeric]

Take it back to the dealer.

[minibike132]

#02-06-05-003G: Exhaust Moan/Vibration Noise (Install Exhaust System Flex Pipe Kit and Exhaust Dampeners, If Necessary)

[minibike132]

#PIP3121E: Exhaust Vibration, Resonance or Moan - keywords 4.8L 5.3L 6.0L A/C acceleration air conditioning fluctuation idle intermittent L59 LM7 LR4 LQ4 LQ9 moan noise resonance rough vibration

[Plainsman]

After a new exhaust system the noise is gone