Hi Frank. Welcome to the forum. The heat shields are tin plates that are bolted to the bottom of the car, above hot exhaust parts, or they can be welded to exhaust parts, typically the muffler and catalytic converter.
On the body, they tend to corrode around the mounting bolt holes. If you can get the nuts lose, adding a large washer solves the problem, otherwise, a lot of people just run additional self-tapping screws through them into the body, but you have to be aware there could be wiring harnesses above there that could get pierced, and you don't want sharp bolts sticking your feet.
Often the welded shields will break lose from the muffler and rattle. You do not have to replace the entire muffler just for that reason alone unless it is rusted through and leaking. Most shops can use a wire-feed welder to reattach the shield. Hose clamps will stop the rattle too if it is feasible to add one.
Sunday, May 23rd, 2010 AT 7:43 PM