I still don't know which parts you're referring to. There's no such thing as an exhaust "box", and I don't know what a "hand coil" is. No one expects car owners to know all the correct terminology, so I'll just offer some observations. In the '70s and '80s it was common to replace the entire exhaust system from the engine to the tail pipe. When one part looked like Swiss cheese from rust holes, all the parts did. Also, pipes were clamped together. That squished a ring around the joints which made it real hard to pull them apart. It was less expensive for the car owner to just put on all new pipes and a muffler.
By around the mid to late '80s a lot of manufacturers started using stainless steel exhaust parts that lasted a lot longer. I live in the middle of northern U.S. Where they throw a pound of road salt on an ounce of snow. My daily driver is a 25-year-old minivan that is rusting away, but all of the exhaust pipes are still original and in good shape. I did, however, have to replace the muffler about six years ago, and that replacement was not made of stainless steel. To buy one from the dealer would have cost over $100.00. I bought a cheap replacement that works just fine for $20.00, but it rusts out every two years. I'm on the third replacement already.
To replace everything in the exhaust system would cost a few hundred dollars so we don't replace parts now unless they're really needed. It's more economical for our customers to charge for the added time to get the pipes apart and save them whenever we can.
If something fell apart in the front, the exhaust system would have been dragging on the ground. Since you didn't mention that is why I'm guessing a heat shield fell off. That is pretty common around here, again, due to the serious overuse of salt on the roads. It's not a good idea to leave those shields off, but driving without one wont cause serious damage. Simply looking at them wont tell the mechanic if one is about to come loose. We can see the corrosion around the bolts but they are usually still firmly attached. If they are about to fall off and the mechanic tugs on one to test it, and it pulls loose, he's going to be blamed, so it's more likely he's going to ignore it. Reattaching them is not a big deal. Usually they just run a couple of new screws through it but you have to worry about those screws poking a wiring harness when they go through the floor.
As for that box you mentioned, my guess is that was the muffler. One of the byproducts of a properly running engine with a properly working catalytic converter is water vapor. That vapor condenses in the muffler where it's relatively cool, especially if it's near the rear of the car. They often have little drain holes near the bottom, but they still rust out faster than the rest of the pipes. The typical repair is to just replace the muffler, and there's usually a short tail pipe that was welded to it, so that gets replaced too.
The next time this happens, ask exactly what is going to be replaced so you'll be better informed before the work is done. Most shops will have books that show each car's exhaust system with each part shown separately. Don't ever assume everything is going to be replaced because that is rarely necessary and it would be terribly expensive.
Monday, February 24th, 2014 AT 8:03 AM