i have this thread on gmfs as well.. heres a link, and ill post the same things ive said there..
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http://www.gmfullsize.com/forum/showthread.php?t=166004
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duno if it matters.. truck is dropped 4/7ish with helper bags..
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every once in a while, after i get home, ill be in my room, and ill hear a sound like someone hit my bed floor with a hammer.. friday i just got back home, and was layin under the truck checkin out the driveshaft, and it made the noise. scared the **** out of me.

ive heard it 3 times now... any ideas?
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some people suggested the bed floor flexing from exhaust heat.. but i dont think the exhaust heat can do that much???


i parked the truck at 10:05.. now 10:23 and it just popped or whatever again..

and earlier i backed up, and as i was backing up it made the noise.

but the tailpipe rights nearly right against the bed.. ran it up high to clear rear end. i also have the middle bed floor crossmember cut off....

IIRC it did it before i ran the tailpipe though..
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just drove 30 minutes(work to home) and then i felt the floor where the pipe is.. definitely warmer than the rest of the bed floor.

then i got in the bed and hopped up and down on the bed floor, its all solid... looked under the truck, cant see anything that would make it make the noise..
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ok now i KNOW its not my exhaust...

several days ago it made the noise again.. i heard it and said yay.. then i hear the front door open, and my mom goes out front. i said what are you doing? she said oh i hear a loud noise, sounded like someone hit your truck.

i left some training for work yesterday.. pull out of parking spot, make two turns in parking lot, then pass some of my friends and i kinda step on it( just enough for it to get louder) and it makes the big *** popping noise. scared the ******* **** out of me.. the truck didnt jump, do anything weird besides kinda make a big boom and i can definately tell its from rear.

then i get home, and about an hour later makes a big *** popping noise again...

this **** is ******* weird!
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sorry if it all looks ran together.. but any ideas? it did it twice today. once while at com as some dude was walking by, it scared the hell out of him.. then when i got home. the one when i get home sounded worse than the others..



anyone have ANYTHING i can check? all the suspension "looks" fine. but hell, i wouldnt rule anything out at this point in time

 

TTT

help!

 

ghost is hittin the switches

 

what do you have going there for the helper bags? is it possible that compressed air is making the noise??

 

what do you mean what do i have going there?

i have a 2?????? gallon tank, viair 380, running to a check valve, then to two 1/4" fill valves and two 1/2" dump valves and then f9000's..

sometimes when i jack up the rear of the truck, and let it down.. the bags wont roll over themselves like they should be, so i just shoot some air to them, then they make a popping noise. but its a distinct noise that doesnt sound like the noise im hearing.

 

mite be crazy could be the where you cut on some of the bed by the exhuast is hot and the metal expanded when it cools down mite be the poping noise. I have 55 gallon oil drums at home when they are in the sun they get warm but when they are in the shade they always make a loud bang noise from the expasion could be a longshot but thats my guess

 

like i said in the first post, i know its not the exhaust because..

truck sat in parking lot for 10 hours, pull out of parking spot, make two turns in parking lot, then pass some of my friends and i kinda step on it( just enough for it to get louder) and it makes the big *** popping noise. scared the ******* **** out of me.. the truck didnt jump, do anything weird besides kinda make a big boom and i can definately tell its from rear.

then i get home, and about an hour later makes a big *** popping noise again...

 

Maybe there's 2 separate popping noises? The exhaust heat theory makes perfect sense, especially since the bed has been modified.

 

yeah the randomness of this makes me agree with budhayes... and in my post above, i was trying to think if something in your compressed air system is suddenly releasing air, like a valve grounding out or something

 

My truck, and others I have worked on do this. In my case, it's the gas tank.