If you have an internal combustion engine in your car, you have an exhaust system. It’s a complex system, and it can have a few common issues that cause problems for your car.
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The exhaust system has multiple functions, from removing exhaust gasses from combustion to providing fuel management feedback to the engine computer.
We’ll discuss the 8 most common issues with exhaust systems and how to fix each one.
If you’re seeing white smoke coming from your car, you should check out this article to understand why.
#1 – You Have An Exhaust Leak
The most common problem you’ll face with the exhaust system is an exhaust leak. The exhaust system has multiple parts with a gasket between the mating surfaces, and these gaskets can dry out and fail over time.
The system is also made from a basic metal that can corrode over time and develop a leak. The tell-tale symptom of a leak is a change in sound from the system as it should become louder if a leak has developed.
How to Fix It
Fixing an exhaust leak isn’t a large job depending on the issue. If a gasket has dried out and failed, the mating exhaust parts should be removed, and the gasket replaced.
If the actual exhaust part has developed a crack, such as a muffler, it may be able to be welded together to fix the issue. If the leak can’t be repaired, the part can most likely be replaced.
#2 – You See Smoke Coming From The Exhaust
Your exhaust shouldn’t be very visible if your car is running well, but oftentimes your exhaust will have smoke coming out if you have a problem. Smoke will typically be in three distinct colors, which indicates what the problem is.
- White smoke indicates you have coolant entering the combustion chamber and it is being burned with the air-fuel mixture.
- Blue smoke indicates you have oil entering the combustion chamber and it is being burned with the air-fuel mixture.
- Black smoke indicates that you are burning too much fuel.
How to Fix It
If you have white or blue smoke, you have a leak that allows coolant or oil into the combustion chamber. Neither of those two liquids should be in the combustion chamber, so you need to determine why that is happening.
Coolant may be coming in from a damaged intake or head gasket. Oil could be entering the combustion chamber from worn or damaged rings on the pistons.
Fixing these leaks will require significant work, and it may be best to take it to a certified mechanic.
If you have black smoke, you have excessive fuel being burned in the combustion chamber. That means an injector is releasing too much fuel due to a worn seal or the fuel injector could have a crack in the housing.
Each individual injector can be replaced, and it may be another job for a mechanic if you’re not confident in the replacement work.
We have previously reported on fuel injection problems and fixes, which you can read here.
#3 – You Have Rust On Or In The Exhaust System
Your exhaust system is made of metal, and many metals develop rust and corrosion.
Surface rust isn’t harmful to the integrity of the exhaust system, but if left unchecked for a long period of time it can eventually corrode through the metal and cause a leak.
The combustion process also produces water as a byproduct and that can corrode the exhaust system too.
How to Fix It
A rusty exhaust can develop a leak that will either need to be welded or the component replaced. Most exhaust systems are made from a basic steel that will corrode over time.
Higher-end exhaust systems may use stainless steel or titanium to reduce weight and prevent corrosion, but they are more expensive than the basic steel components.
#4 – You Have A Faulty Oxygen Sensor
Oxygen sensors have been used for the last 40 years to measure the amount of oxygen left in the exhaust gas after the combustion process in the engine.
That information is sent back to the Engine Control Unit (ECU) to understand if the engine is adding the correct amount of fuel for the combustion process. If the oxygen sensor is faulty, it can send the wrong information to the ECU.
How to Fix It
The Engine Control Unit has pre-determined resistance values that it verifies for each oxygen sensor.
If the ECU recognizes a problem with an oxygen sensor it will illuminate the Check Engine Light (CEL) to signify that there is a detected problem. You can check the resistance of the oxygen sensor with a multimeter to verify it is faulty, and it can be replaced with a new one.
Oxygen sensors are recommended to be replaced as a set, so if you replace one you should replace all oxygen sensors at that time.
#5 – You Have A Blocked Catalytic Converter
Catalytic converters use the heat in the exhaust gas to burn any leftover contaminants after the combustion process in the engine.
If your engine is not burning all the fuel in the air-fuel mixture, that leftover fuel can damage the internal honeycomb mesh in the catalytic converter until it fails and blocks the flow through the catalytic converter.
If the catalytic converter is damaged, it should trigger a Check Engine Light (CEL) to signal a problem. You can then use a diagnostic scanner to determine the cause of the CEL.
How to Fix it
A blocked or damaged catalytic converter can’t be fixed. It must be replaced with an approved component, and they are becoming harder to buy over the counter.
You may have to buy a replacement from a dealership, or a professional mechanic may have to install a replacement.
For a more detailed look at problems with catalytic converters, read our article here.
#6 – Your Exhaust Brackets And Hangers Are Loose Or Broken
The exhaust system is suspended under your car by a series of brackets and hangers.
The exhaust components will have brackets welded to the piping and mufflers. These brackets use an insulator made from rubber or polyethylene to connect to the hangers.
The hangers are connected to the car, either by welding or a nut and fastener combination. The welded brackets and hangers can corrode over time and allow the exhaust system to hang without support.
They can also loosen due to degraded insulators or fasteners that have loosened.
How to Fix It
A corroded or degraded hanger or bracket should be replaced if it is causing a structural problem with the exhaust system. You may develop leaks between components without proper support from the exhaust system.
A degraded insulator can be replaced with a new insulator, and loose fasteners can be tightened to manufacturer specifications.
#7 – You Feel Excessive Vibrations In The Exhaust System
The exhaust system should be properly insulated from the car to prevent excessive vibration from being transferred to the passenger cabin. Worn-out components can transfer excessive vibration from the exhaust system and reduce your comfort while driving your car.
How to Fix It
If you feel excessive vibration or a change in the driving experience of your car, you should investigate why it is happening.
The feeling of increased or excessive vibration is a definitive symptom of an issue.
Degraded insulators, broken or corroded hangers, or a damaged component can transmit excessive vibration, and you should fix the issue casuing the vibration to occur.
#8 – You Detect Increased Engine Noise
Your engine and exhaust system work in combination to burn an air-fuel mixture and then release the burned gas.
A degraded or blocked exhaust system can reduce the amount of gas being released from the car’s exhaust system, and that change may contribute to a change in noise. If you detect increased engine noise, you should immediately investigate why the change occurred.
How to Fix It
Increased engine noise may occur because the exhaust system is degraded or blocked.
The exhaust system change may cause the Check Engine Light (CEL) to illuminate. The CEL may illuminate due to other changes such as a faulty sensor or a leak.
Use a diagnostic tool to determine the symptoms causing the CEL. If a component has become faulty, it can be replaced with a new one.