I have an 04 with 80,000 on it. Iam getting a thumping noise around 30-35 mph and when you let off the gass just coasting. It sounds like its in the front but if you open the door it sounds like its coming from the rear. So i took it to the dealer a couple weeks ago and they tore it all apart checked the rear end the front end and they didnt find any thing. They said bring it back when its dry out to put a chassis ear on it. does any one have any ideas? the front suspension is all new. front and rear diff fluid is new,brakes new,tires new, I checked the front diff bushing and even put it in drive on the car lift.

 

I was like crazzy with a bumping noise . sound like some one is bumping at the truck floor . ussually happened while cruising .
Check almost any thing and nothing . Ended replacing the shocks for some other reason and this was the problem .
Yep .. I dont understand why but the noise came from te old shocks .
Are yours still the OEM

 

I'm glad someone brought this up.

Mine has the oem shocks & does this. I also get vibrations (still), but haven't done anything to the suspension. It's interesting that it could just be a shock issue.

That's on the list of replacement parts, after wheels/tires.

 

Yep I still have the OEM shocks.

 

Best bet is replace the shocks . which you will have to replace anyway
I used Bilstein .. you will find a few thread with info on which to buy ..

 

H2miami im thinking of going with this Bilstein Part S/DShocking5100 - 4 5100 Series Shocks For Most Lifted Trucks with Black Shock Boots - 4 Wheel Parts my 04 has the OEM shocks and the noise its killing me ....

 

For some reason I dont remember the rear shocks are diffeeent of front ... here it is how most people configured

Bilstein 24-186735 Front Shock for GM K2500 and 3500

Bilstein (24-185912) 46mm Monotube Shock Absorber for rear

Bilstein 33-174525 46mm Monotube Steering Damper


BTW my H2 is not lifted ... I dont know if the confg will works if lifted

 

Well so far I have new shocks all the way around and still have the same noise. I took it back to dealer they put the chassis ears on and they said its coming from the rear but they cant figure out were.

 

If you think it's something that's visible, go out and buy a gopro, mount it to the bottom & try to duplicate the problem. I've done this before. It's amazing what you can find.

A gopro hero 3+ (cheaper than the hero 4) is a solid unit if you think you'll use it a lot. Having something at least HD makes it a lot easier to see what's going on. So long as the unit can hook up via wifi, you can use your phone to view what is going on in real time. Might help if you can get a buddy to watch & listen while you duplicate it.

 

Check your brakes. I had a similar noise with the same low speed on my DD and it turned out it was the brakes. Just a thought...