[debargha]

There is a noise from somewhere behind my car while starting to move or acceleration. The noise is something like loose coins in a container.
What do you think might be the cause? is it something serious and do I need to take to the shop? Is it expensive repair cost?

I also have a noise sometimes from the engine after starting the car. not sure how to explain the noise but sounds like coming from some belt moving. I recently changed my driving belt so it should not be it. any ideas? may b i should record the sound and post here.
thanks

 

[schumicat]

sounds like a metal exhaust shield rattling. try whacking muffler and exhaust pipes with rubber mallet to try to make it rattle. could also be broken cat converter (same test).

 

[rudeney]

The first noise could be your catalytic converters failing. This would be my guess if you are over 100K miles. The molten material in them them will deteriorate and dislodge, then cool as it flows down the tailpipe, sounding like coins or marbles rattling around in the pipe. If this is the case, you need to replace the entire exhaust system. Just replacing the converter will leave the muffler and resonator clogged.

As for the other noise, is it sort of a chirp? You may have a bad bearing on a belt-driven pulley. I'd remove the belt and check the various pulleys by hand to see if any are rough.