Rattling Noise Under the Engine

[percy]

Hi.

I have not checked the under carriage yet but I hear a rattling noise under when on idle since I am standing outside.
Had anybody had this problem before and fixed it?
Thank you.

Percy

[jk88]

Could be something as simple as a loose heat shield. Does it go away under acceleration?

[percy]

I have not noticed that the sound will go away when accelerating. I will check the car this weekend and check what really is making that noise.
thanks for the feedbacks.

[nordwulf]

Check the heat shield that covers the turbo. I think mine came a bit loose at some point.

[percy]

I will check that. I have read on some forums too that I also need to check the heat shield.
Thanks.

[percy]

At last, I was able to take a look at where the rattling sound that comes out every morning at first start of the car.
I had lifted the car and the engine was running. Went under the car and no rattling sounds comes from any of the following : heat shield/fog light mount/turbo plate/catalytic coverter. it is around high 60's a while back. can't reproduce the sound so I did an experiment.

This sound came out when I had turned on the AC at max cold and the sound came from the pulley areas closest to the front grill. the serpentine belt has just been replaced last nov2011. could this be a compressor related issue?

So, i have 2 sounds now that I am trying to pin point.
Any reply is appreciate.
Thank you all.

Percy

[percy]

Update, I had a mechanic listen to to the sound with their stetoscope while parked. the mechanic tried to locate where the sound comes from. he said the tensioner, compressor, other "moving parts" accessed from hood is fine, he was not able to lift the car for further inspection.

the sound is very evident when the car is on AC- max, and when the car is on gear. While driving, i can hear the sound when stopped but when I put the gear on neutral/park the sound almost disappears.

is there a mechanical part that might vibrate when the car is on gear?

Thank you.