Strange cold startup noise

[Zer0VIBE03]

When the car is cold and as soon as I toss it into gear (Reverse out of the garage usually) it makes a prattling noise... Thought it was a loose bolt or something, but had a place replace a bunch of bolts and clips that went "missing" under the car. Still makes the noise.They checked the heat shield and everything, but it doesn't go away.When the car warms up, it doesn't make the noise.Couldn't leave the car overnight to let them duplicate the noise, and I would love to get you guys a video but I have no idea where my camera went. help?

[djkeev]

High likely hood of the internals on the exhaust have become loose and rattle until they expand from the extreme heat of the exhaust.Dave

[cptnsolo77]

Only in reverse? Does it make the noise in drive when its cold?

[Zer0VIBE03]

it makes the noise in drive as well, but it doesn't seem to be as loud. Maybe I'll take a day under the hood and just tighten bolts or something.

[cptnsolo77]

Sounds like it might be your belt tensionener piston. Try Doing a search. Good luck.

[rubendeje]

I have the same problem with my 09 GT in that when first started and placed in gear it sounds like a diesel for the first minute of driving then goes away. i thought it might be valves, but not sure.

[wallyuwl]

+1 on it possibly being the belt tensioner.

[09vGT]

My 09 GT makes a noise when reversing too. Has always done it. Thought mine sounds like more of a rubbing noise. Sometimes worse than others..