Is Your Car Noisy? It Could Be The Muffler

Dear Tom,

I own a '99 Ford Taurus. It's so loud that it sounds like a truck. Do I need a new muffler? If I have to fix it, can I repair it myself? What happens if I don't fix it immediately?

Joe from Burlington, VT

Joe,

I would fix the exhaust system for a few reasons. First, the safety of you and your family is of critical importance. Exhaust systems are designed to channel the burned gases, which include hydrocarbons and carbon monoxide (both harmful to humans), safely away from the vehicle. Exhaust leaks result in these harmful exhaust gases getting trapped in the underside of the car and finding their way into the vehicle's cabin. Second, a certain amount of exhaust backpressure or restriction is built into the system to create venturi action, resulting in snappier engine performance and better breathing. Remove this and the engine performance suffers, not to mention the computer system gets thrown off because of reduced exhaust flow. Third, violations of the local noise ordinances in your town can result in "wallet drain" due to fines from local authorities. Get it fixed by a qualified shop; it's cheaper in the long run.

Tom

Joe brings up some valid questions. Let's take a closer look at them as well as other considerations.

It is the muffler?

This is impossible to determine without raising the vehicle on a lift and inspecting the exhaust system. That would be the first order of business.

What happens if I don't fix it immediately?

Mechanically, the oxidation process (assuming it's rusted) spreads to other exhaust components connected to the muffler (in this case the adjoining pipes) and thus they rust too. Also, the computer system will try to compensate for the lack of exhaust flow it "reads." Remember, exhaust flow is measured by the computer; this measurement is a part of the whole mix of data used to adjust the drivability system during operation. Finally, it will get louder and attract undue attention, resulting in a fine.

Why do mufflers break down?

Exhaust systems in general are exposed to weather elements as well as road clearing chemicals. Living in VT as he does, Joe's car is even more subject to the effects of rust and oxidation. Salt belt states (states that use snow and ice clearing chemicals) typically use liquid sodium, calcium & magnesium chloride and rock salt to clear roadways of snow and ice. This concoction eats metal. Finally, internal condensation is a factor that eats exhaust systems. When a cold car is started, hot exhaust gas courses through the cold exhaust system, causing condensation to form. Water and oxygen together cause a catalysis called oxidation or rust. Hence the system is eaten from the inside out.

If I don't get my exhaust fixed, can my car catch fire?

This is indeed a possibility. Here's how: If the exhaust leak is close to the floorboards of your car, the heat that comes from the hot exhaust gas can burn the insulation between the carpets and body panels. If the exhaust leak is close to a fuel leak, hot exhaust gas can act as an ignition agent and thus cause a fuel-based fire. If the exhaust leak is in the engine compartment due to a leaking exhaust manifold, wiring can catch fire and cause an under hood fire.

Should I use a car dealer or a muffler shop to repair my exhaust?

Some cars (like Ferraris) have such specialized exhaust systems that to go anywhere else but a dealer could result in performance problems. In the end, the customer pays more for the job than going to the dealer. On these cars special tools, operations, and parts all play into the repair. If the shop working on the car is not familiar with the vehicle's idiosyncrasies, it could cost you more than it should. I don't like paying for an inexperienced person to go to school on my car. That said, for most vehicles, aftermarket exhaust shops offer a great alternative to OEM exhaust part replacement.

Send your questions directly to Tom Torbjornsen at carownership@aol.com and he might answer them in an upcoming column.

Other car questions answered:

- Do I Need To Warm Up My Car?
- Oil Change Intervals: Can I Wait?
- Why Do My Brakes Squeal?