Tips for Diagnosing a Car's Exhaust System

If your car's exhaust system is breaking down, you may be able to diagnose it yourself with a visual inspection and a few simple tools. Whether or not you can make the fixes on your own will depend on the level of expertise you have with repairing a car and the tools you have, but at the very least, you can tell a mechanic what you found and where you found it so he or she can know where to begin looking when it comes to exhaust repair. Note a few troubleshooting tips to consider.

1. Rattling

Rattling in the exhaust system is often caused by loose connectors that hold parts of the exhaust in place. You can put the car up on blocks and run it while checking underneath it, being careful of your safety of course. Note if you see any connectors from which the muffler or other pipes hang that are rattling, and if these are rusted beyond tightening and need replacing.

You may also note if the heat shield, which sits between the muffler and manifold, is rattling. This shield is welded into place and if the weld comes loose over time, it will begin to rattle. You may not see it rattling visually but you can slide a flat screwdriver between the shield and the catalytic converter and see if it seems loose. If the shield itself is rusted and damaged, it may need replacing altogether.

2. Louder than usual sounds

If the car's muffler has a hole, you will notice some loud sounds from under the hood and especially when you accelerate. However, if you notice a very loud sound when you accelerate but the muffler to your car itself seems intact, this may be the fault of the catalytic converter. This piece looks similar to a muffler but is usually a bit flatter and larger, and it sits along the pipes of the exhaust system to filter emissions from the car.

The converter itself may have come loose, it may have a hole, it may be rusted so that it rattles as it works, or it may be clogged which also causes it to rattle as it filters exhaust. You can check under the car and note if the piece is loose and if so, this can cause the loud sounds you hear when you turn on the car. If it's not loose and seems in good shape but still rattling, it may simply be clogged and needs replacing or repair.