I had the same problem with mine. It took me forever, but I finally found what it was. It was the steel brake line that runs across the top of the firewall. At certain RPM's it would rattle in the clips that hold it, and it was driving me crazy! What I did was took a zip-tie and fastened the line to a hole that is in the module mounted on the pass side firewall. There is a nice bend in the line that lines up great with the hole in the module. Just snugged it up so that it wasnt rattling in its clips...and the noise is gone!

 

Mine rattles as well. I started it up one morning and ran to the front. On mine it's my air box moving around. It drives me nuts. There is a bolt inside the air box right? I haven't checked that yet.

 

Like a buzzing sound? That is your air filter box making contact with the inner fender, give it a good wiggle and shove it toward the TB (you might have to loosen the intake clamps first), then check it. Sometimes the air filter boxes need to have the bolts holding them to the top of the wheel well loosened up and then tightened after adjusting the play in the mounting of the air filter box.

 

If it is motor noise, and not from something loose or in improper position under the hood, then it is your I5 timing chain tensioners. Take a look at my post #17. https://www.hummerforums.com/forum/h...3-21813/page2/

 

I have the K&N intake on my 06. it rattles sometimes and needs to be adjusted . It vibrates against the hole the intake sticks through.

 

Was having trouble posting a few days.

Thanks for all the suggestions. I had secured the brake lines previously so that was ruled out. It's not a buzz Doc, more like a wire tapping on metal rapidly. I can't hear it outside the vehicle or with the hood up so I hadn't checked the airbox but I will.

Another possibility I was thinking of was the evap canister. I put my ear on the body right near the antenna and could hear it quite well.

I pulled my fake airbox cover yesterday to look under there and I didn't hear it this morning. That may have been moving around I suppose.

 

I finally found the real culprit. Thanks for getting me in the right area Doc.

Apparently at some point when I pulled my filter box cover i dislodged the clip that holds the overflow hose to the side of the engine compartment. Pushed that back in and no more rattle.

It's incredible how much a noise can migrate. Even once I found it, it was hard to hear outside of the truck.

Thanks for all the suggestions.

 

I appreciate all the comments on my issue I believe Doc Olds hit the nail on the head!!! When I first start up in the morning I hear this noise and all the comments on the quoted thread relate directly to what I am hearing. (Thanks Doc Olds) My concern now is whether or not I need to worry about this? I have about 55,000 on the clock.. Do I need to be concerned??