Rattling when in reverse- only in cold temps.

[hoakes3]

Hi, I was wondering if anyone could help me with a rattling noise I've been dealing with for over a year. I have a 2008 Corolla and last winter I began to notice a rattling noise under the car when I'd put it in reverse before it warmed up and only when it was colder than 30º. It didn't seem like anything serious so I just blamed it on the cold. As it got warmer it never happened so I completely forgot about it until this past winter. It's been getting louder and louder (still only in cold temps and when in reverse and sometimes going over bumps), it just sounds like something is loose under the car- maybe the heat shield?
Anyway, I've taken it to the dealer and they can't find anything, does anyone know what it could be?

[mikered30]

Belt tensioner. Check for deflection in the belt during a cold start up on a cold day.

[Rdkill]

Same issue here, I got under the car when it was making the noise and it appears the exhaust is hitting the rear bracket, near the rear wheels. I haven't done anything about it yet as its just now starting to get warn here, but I have a hard time believing the belt tensioner could make such noises. It sounds like exhaust rattle to me.

[impulseRED]

Originally Posted by Rdkill

Same issue here, I got under the car when it was making the noise and it appears the exhaust is hitting the rear bracket, near the rear wheels. I haven't done anything about it yet as its just now starting to get warn here, but I have a hard time believing the belt tensioner could make such noises. It sounds like exhaust rattle to me.

it most likley is....... i have the same "problem" it happens when somethings gets kicked up under your car.... for me it was a concrete bag lol.... the pressure from my car going voer it at 90 sucked up to the frame and tore it in half flung it 30 ft in the air and landed on some guys windshield.... poor guy all i got was a rattle and the bottom of my car was white for a while... lol