I have a 98 Honda CRV with a metallic rattle near my muffler. My mechanic says that the catalytic converter heat shield has rusted out and disintegrated. My questions are: 1) if the heat shield is gone what would cause the rattle; and 2)do I really need to get it replaced since it is a $200 job?
It depends on the car and what heat shield is shielding.
I would suggest going to a local independent muffler shop for a second opinion. Chances are you can do fine with a much cheaper solution.
You can continue to drive with a rusted heat shield and a rattling noise. This is not an urgent project. Or you can do as Joseph suggests and ask a muffler shop about inexpensive repairs.