Bought a new to me Hummer 2009 H3 Alpha. 97k miles. Texas Car. Test drive and drive home was fine. Took the care out a week later and I am hearing a sound that sounds like something is loose and/or something is continuously moving.

When I say loose, I am referring to maybe a heat shield or something simple like that. Think Metal on Metal sound. I got underneath and everything appears tight and clean.

When I stopped at a stop light, with the car not moving anymore, I would continue to hear this noise plus I heard sound coming from the shifter/console inside. When the car is stopped and running, the car has two things moving...the engine and the transmission right? Engine is fine. No knocking, or smoking, squeaking, etc This leads me to the transmission or the transfer case?

The transmission was replaced 2500 miles ago in Feb of this year by GMC dealer.

No messages on dash.

I am having trouble duplicating 100% of the time.

 

Is a Truck a Car?

Car vs Truck:

 

After I posted I was going to make some edits before your post....well...this site does not allow you to make edits after you post.

I choose truck or SUV?

 

I am trying to duplicate the sound. Seems when I get it up to speed around 55 or so and then come to a stop...The noise continues. Truck is stopped, yet still running, and the noise will appear. And then goes away. And I think I can make the sound go away with shifting in park...Need to test that. So it cannot be cv joint, shield or something static in place.

I did hook up the OBD tool and zero codes show.

 

Truck shifts fine. No clunking or grinding. It gets up and goes. I did test 4 high and 4 Low. They work fine.

 

Check underneath with a closed fist or Rubber Mallet

You Tube

 

Yep, did that with my fist underneath...and I used a huge long screw driver to push on some shields in the engine bay entering from the top.

It a continuous motion sound. Something is moving. I would not think its a shield or loose bracket.

Come to a stop after driving...and there is a continuous sound occurring. Will see if I can get a video sound

 

check the torque converter bolts,
also if you can check the starter maybe it is staying engaged.
another source of noise can be a cracked flywheel.
if you can get a hold of an endoscope camera look though the inspection hole on the bell housing.

 

From what I can tell looking in the holes, everything is tight. I will be honest, I did not do a thorough check. Meaning put in neutral and push it and move the fly wheel. I can check that tomorrow in the light.

If a bolt was loose or the fly wheel was cracked wouldn't this sound be more obvious and always occur? If it was the starter would I hear the starter always starting?

Its interesting you say starter, earlier I was googling something called a transfer case motor. I think it acts like a starter but I think it was for engaging the different high/low gears. Maybe its shorting and acting up to cause intermittent engagement?

The sound is like two light gears attempting to mesh. I say light because its not grinding.