That is what mine was doing but i found the rattle the hood hinges get wore and loose allows the hood to shake and rattle.

Easy fix i just stuffed a rag under each hing with hood open so when you close it up it will put tension on the hings. Presto rattle went away .

I have fixed every rattle in it silicone works great in the spots like plastic molding that may be rattling remove molding put a few dabs here n there reinstall fixed.

 

Sounds like a place we didn't check, hopefully it is the most obviuos, but also the most overlooked place Will try the rags under the hood near the hinges and see if the sound stops.

 

Check your hood bolts. I had a similar problem that took me a year to find. It turned out to be the R/S hood bolt was loose.

 

Mine does the same thing.

 

Seems that is what it was, the hood bolts/mounting bracket they go through are worn out. Had a piece of foam stuffed under there the past two days, as walleye recommended, and no more noise from that area! With the foam in there you can see how the passenger side is out of alignment and off. Going to replace them today or tomorow, thanks for the sugestions and help

 

it might be hood hinge bolts rattling i know it sound crazy but it drove me nuts check hinge bolts if their is a gap then you need to put at least 1 washer on the shoulder side of the bolt on both sides try that

 

thats my problem, and yes goes away when braking. its been months and i think ive finally figured it out. spent HOURS underneath testing everything. so your saying it wont harm rotors or wheel bearings?

 

2000 trailblazer its a GM thing once you get rid of one noise 3 others pop up.