Exhaust System Replacement

How often does your exhaust system need service?

Depending upon the geographic location of your vehicle, exhaust systems may or may not need frequent attention. Typically, the exhaust system in a car does not need much attention until higher mileage or advanced years. Most cars do not need any exhaust work for upwards of 8 to 10 years due to the corrosion resistant, stainless steel used in exhaust systems installed in the factory. However, repairs will become more common and more expensive as components age and develop holes and leaks or when they fail completely.

What are the symptoms of a faulty exhaust system?

A louder sounding exhaust is the easiest symptom to identify, and a technician can easily point out where the leak exists when the car is on a lift. The prime culprits for leaking are the flexible weave near the front of the exhaust, and the union where two flanges are bolted together. The flexible weave allows for the exhaust system to move around when the car twists and turns. It is the weakest part of the exhaust in terms of thickness and it takes the most abuse. The flanges are made from anodized aluminum, which does not resist rust and oxidation as well as stainless steel, so they begin to rust sooner. Where these flanges meet is also a spot that tends to collect moisture. Sometimes, the system can be repaired with some new flanges and a new gasket to seal them. As the system ages and develops holes or more significant leaks, welding may be an option to repair through either patching a hole or cutting out rot and fitting in a new piece and welding the gap. At some point the system will need replacement in larger pieces.

How does the exhaust system work?

The exhaust system has three important functions.

  • The most obvious function is to reduce the sound of the exhaust. Mufflers and resonators, found near the end of the system, use a series of baffles to lessen the sound without impairing back pressure.

  • Exhaust system routes hot gases away from the engine, and allows these gases to safely exit the car away from potential passenger contact near the door areas. Usually, the exhaust will exit from the rear of the car, although a pipe that comes out from the side further down from the doors is not uncommon, especially in pickup trucks.

  • The exhaust system provides emission reduction with the use of a catalytic converter. Here, the exhaust gas actually rises in temperature as it passes through several screens made from precious metals (platinum,selenium) where a chemical reaction changes hydrocarbons and carbon monoxide into oxygen and water. The onboard computer monitors this chemical reaction through the use of oxygen sensors before and after the catalytic converter.

What can happen if this service neglected?

If not repaired when required, a neglected exhaust system will lead to higher repair costs, rejection of state inspection and inability to drive the car legally, and ultimately the severe impairment of engine performance.

Small holes in the exhaust system can usually be repaired with welding and patching, but if ignored will grow larger and require component replacement at higher expense. While the car may still be drivable with a loud exhaust, passing state inspection becomes doubtful with chances for tickets and fines becoming more likely. With no attention paid to the exhaust system, leaks especially before the catalytic converter will add unmetered oxygen to the exhaust mixture. The computer does not realize that a leak exists, instead this unmetered oxygen is understood as a poorly performing motor - that too much air is in the fuel air mixture.

The computer will attempt to correct this poor performance by adding fuel. This richening of mixture will cause misfire, carbonization of the valves and intake, and loss of performance in the engine. In addition, the unburnt hydrocarbons from this rich mixture will eventually overwhelm the catalytic converter causing it to fail and need replacement. Repairs at this point will be costly.

Pricing will vary based on the exact type of repair that is needed. Either way you look at it, the replacement of catalytic converter is expensive. In some cases this repair will reach into the thousands of dollars range, and unquestionably, the type of car you drive will determine price. Fingers crossed it's just the muffler.

Most automotive service professionals can perform this service. Keep in mind, pricing will vary by location and your vehicle make and model. Save time and money by using Openbay to compare pricing and book an appointment with a service center in your area.

Service article written by an ASE Master Technician