Amy's Amazing Auto Service and Repair Blog

How to Quickly Troubleshoot Your Car's Exhaust System

by Derek Davidson

Your car's exhaust system works to direct emissions from the car's engine out the back of the car, allowing the engine's combustion to work properly and protecting you from breathing in those dangerous fumes. The muffler also keeps the car quiet by absorbing vibrations created by the engine and exhaust system. When your car's exhaust system needs some repair, you may expect to hear the car rumbling loudly and this can certainly mean that you need a new muffler, but note a few tips for troubleshooting other problems with a car's exhaust system as well. 

1. Poor gas mileage

Suddenly needing to fill up at the pumps more often than before can be caused by a number of problems with your car, but the exhaust system is usually the culprit. If there is a leak in the exhaust, this can allow too much air back into the engine. In turn, it may need to work harder to produce the combustion it uses for power. If this poor gas mileage is accompanied by a sulfur or burning smell from under the car, this often means that the exhaust is leaking. There could also be a blockage in the exhaust system; if something has rusted so that a part of the exhaust pipes have fallen into the airways, this too can make the car's engine work harder than it should. 

2. Box of rocks

If your car produces a rattling sound that resembles a box of rocks being shaken up every time you sit idle, this is usually a problem with the catalytic converter. The catalytic converter looks something like a muffler and its job is to convert toxic fumes into emissions that are less toxic by filtering them through the exhaust system. The piece works with a honeycomb-shaped filter and if the converter itself should become clogged or the filter is damaged or clogged, you may hear the unit rattling around as air tries to pass through this part of the exhaust system.  

3. Buzzing

The pipes and other pieces of your exhaust are held in place by hooks and over time, rust can often weaken these connectors and the areas where pipes are joined to one another or other pieces. When that happens, the pipes may not actually break away but you may hear them vibrating and creating a buzzing sound. The sound may get louder as you accelerate and more exhaust is being pushed through the system. Typically you can have the connectors replaced or use muffler tape to wrap around the areas where the pipes are joined to keep them in place until you're ready to have the exhaust system replaced altogether.