Odd noises

[ThomasC]

Anyone have these problems? Are they normal?

When I start my LTZ, about 3 seconds later, I hear a weird rattle/chirping sound coming from the rear. It lasts from 2 to 10 seconds.

When I drive at any speed and the engine comes to 1500rpm, I hear something vibrating under the hood. Its kinda loud.

 

[wedtwuk]

Not sure if this is your problem but the LTZ has the air suspension. There is a pump located in the rear underneath that will start when the ignition is turned on if it needs to pump up any of the shocks. That may be the noise you are hearing. Not sure about the sound sunder the hood. I haven't heard anything strange there in mine.