It could be any of the belt driven accessories including a water pump.
January, 27, 2013 AT 2:48 AM
What you may be hearing is the timing chain rattling against the block. On high-mileage Stratus's upon initial start-up they will rattle for a few moments and then the noise goes away. If you have the 2.7 make sure you change the oil promptly or you will have major engine damage due to sludge build-up. Google this engine, you won't like what you hear.