What is this intermittent booming noise coming from the back?

[Buz]

I do have the HK system but to me it almost sounds like the noise comes from different corners of the truck at different times which would tell me it has something to do with the suspension.

Interesting. For me the booming always sounds like it’s in the far back of the cabin.
I wonder if it is the sub vibrating on the thin back wall.
So anyone have this booming noise and NOT have the HK system?

 

[Aseras]

fold your rear seats up and see if it goes away. check the flip out cargo retainer too. when its flat it can bang as well.

 

[Buz]

fold your rear seats up and see if it goes away. check the flip out cargo retainer too. when its flat it can bang as well.

Appreciate the input. Cargo retainers are in the up position. It’s not a banging sound like something is loose. It’s a tight drumming sound that coincides with mild rear suspension action. I’ll try folding the seats up but not sure what that would mean.

 

[Buz]

Any chance you have a hitch in ? And that’s what bounces slightly when u notice it

No hitch. Again it’s a tight drumming sound. It does not sound like anything is loose.
Most noticeable when all windows up and radio volume down.

 

[Aseras]

You have rear wheel liners? Does it do it at low speed or highway speeds?

 

[Buz]

You have rear wheel liners? Does it do it at low speed or highway speeds?

Removed them yesterday still boomy.

Actually just noticed there’s about 6” of hollow space betwteen the carpet on the back wall and the actual back wall itself behind the rear seat on the drivers side. This large hollow space might be causing the noise. Will experiment with this.

 

[Vinnie.]

does it sound like a piece of sheet metal flexing? if you could imagine holding a sheet at one wend and wiggling it back and forth, it would make a sound similar to how you described.

Edit: Wend=End

 

[Buz]

does it sound like a piece of sheet metal flexing? if you could imagine holding a sheet at one wend and wiggling it back and forth, it would make a sound similar to how you described.

Edit: Wend=End

Yes it kind of does. It’s something in the back wall/floor area.

 

[Buz]

I HAVE DISCOVERD THE CULPRIT! (or should I say, culprits)
It's the two wall mounted vents on the rear of the cab. They are about 4" x 4" each. One is directly below the sliding back window and the other is next to it behind the passenger side rear seat.

Pulled all carpeting off the back wall last night and had the wife drive 39mph (most common speed that makes the booming noise) with all windows up while I was in the back with a flashlight. It's those damn vents.. The flaps are designed to only let air OUT of the cab. They are shut normally and never allow air to come IN the cabin. The vent flaps are super lightweight rubber (or maybe even paper) that 'flutter' with all the windows up at around 35-40mph. It's as if air wants to come in and go out at the same time. At slower speeds the vents flutter at a very fast rate and vibrate the back wall as well which is likely the 'booming' noise we're hearing. While they were 'fluttering' I stuck my fingers in the vents opening up the flaps and wouldn't you know it the fluttering stopped. This must be why as soon as you open a window the booming stops.

The problem is we need those vents to function as designed and let air out of the cabin for door closing, HVAC operation and airbag deployment, so to cover them up is DEFINITELY not an option. I thought about removing the flaps and applying some kind of foam filter instead, but not sure if that will introduce more road noise, humidity and dust into the cabin.

Anyone have a good idea how to stop the fluttering without either opening a window or removing the flaps and having the vents wide open all the time? The vents are removable. It's difficult to get them out but I believe you can force them out.

 

[Scram1500]

I always suspected those vents, I had them covered with small cardboard box stuffed with a shop rag. Then everything got Dynamat. It was super quiet but air could not escape the cab and the door seals whistled above 40 mph. Perhaps adding an air dam of sorts where the bed meets the cab will stop the low pressure area behind the cab which is sucking the flaps open

 

[Buz]

I always suspected those vents, I had them covered with small cardboard box stuffed with a shop rag. Then everything got Dynamat. It was super quiet but air could not escape the cab and the door seals whistled above 40 mph. Perhaps adding an air dam of sorts where the bed meets the cab will stop the low pressure area behind the cab which is sucking the flaps open

You talking about the solid rubber piece outside down low between the bed & cab? Mine has that.
Can't believe engineers didn't notice this noise and address it.

 

[Scram1500]

You talking about the solid rubber piece outside down low between the bed & cab? Mine has that.
Can't believe engineers didn't notice this noise and address it.

That is correct. I'm wondering if a piece of rubber up high, above the vents, will stop the flapping

 

[Buz]

That is correct. I'm wondering if a piece of rubber up high, above the vents, will stop the flapping

Guess I could shove a big towel down in between from the top and see if it stops. If so, a more permanent fix might be a long piece of foam or rubber that could be wedged down there.

 

[Scram1500]

Guess I could shove a big towel down in between from the top and see if it stops. If so, a more permanent fix might be a long piece of foam or rubber that could be wedged down there.

A pool noodle might work pretty well

 

[Buz]

A pool noodle might work pretty well

Great Idea.
If its wedged in there tight enough right above the vents maybe it will stop the back wall from vibrating like a drum causing the noise.

 

[NewRam92]

There has to be a solution for this other than a pool noodle right? I mean my goodness, we pay enough for these trucks! Mine doesn't have the booming sound you're mentioning, but I'm curious as to why you have it and I don't....

Do you have a video of the noise? Have you asked your dealer about a solution? Maybe there's a bulletin/case number for something like this already

 

[Buz]

There has to be a solution for this other than a pool noodle right? I mean my goodness, we pay enough for these trucks! Mine doesn't have the booming sound you're mentioning, but I'm curious as to why you have it and I don't....

Do you have a video of the noise? Have you asked your dealer about a solution? Maybe there's a bulletin/case number for something like this already

You may have the noise and just not notice it. You'll only notice it if you drive in complete silence (no radio) with the windows up. I personally like to drive this way a lot.
And it occurs mostly at speeds below 45mph.
I trust myself more than a dealer with this particular issue. In fact I isolated the cause yesterday.
If a pool noodle fixes it, I will be satisfied and forget about it. It's an engineering issue caused by the venting and a thin rear cab wall. A dealer is not going to fix it.

 

[NewRam92]

I'm an engineer by trade and totally understand your line of thinking (if you want a job done right, do it yourself). I'm OCD when it comes to any sort of rattle or noise inside when I'm driving. I listen to music on a low level a lot. That's why I asked if you had a video of the noise, I'm just curious myself....

 

[Jeffjad]

Those of you hearing this drumming sound do you have a quad cab or crew cab? I have a crew cab and drive in silence frequently but never experienced this sound at any speeds. Just curious if it is specific to cab size???

 

[Buz]

Those of you hearing this drumming sound do you have a quad cab or crew cab? I have a crew cab and drive in silence frequently but never experienced this sound at any speeds. Just curious if it is specific to cab size???

I have a Limited with is the full size cab.
If you have not heard a drumming noise you may want to bow out of this thread now before you begin to notice it.
I purposely don't read problem threads when the issue in the thread title is something i haven't experienced. It may open my eyes to something I just hadn't noticed before, you know?

I think it would be hard to record the noise with a cell phone. I can try though.
If you really want to chase this issue drive at 39mph with all windows up and listen for booming in the rear.