Exhaust Leak Symptoms and Causes | How to Fix Exhaust Leak?

As your engine runs, the exhaust gases and noise from combustion are routed through an exhaust system. The exhaust system safely routes toxic gas to the rear of the vehicle, away from the passengers and driver. Rust, damage, and worn-out gaskets can all lead to an exhaust leak, and exhaust leaks can impact your vehicle’s performance and even your health. This article mainly explains the symptoms, causes, and repair cost of the exhaust system leak.

What is an Exhaust Leak?

An exhaust leak is a hole (or other defects) in your vehicle’s exhaust system that lets toxic exhaust fumes enter your cabin instead of exiting your vehicle through the tailpipe.

Exhaust Leak

Engine exhaust contains poisonous gasses like carbon monoxide, nitrogen oxides, phosphorus, metals such as lead, and unburned fuel (hydrocarbons).

An exhaust leak can endanger you and your passengers if the fumes build up in your cabin faster than your car’s ventilation system can evacuate them.

Exhaust leaks can also compromise your vehicle’s fuel efficiency and performance, make your ride noisier, and damage your catalytic converter.

What Is an Exhaust System?

A car’s exhaust system is an interconnected assembly of pipes, connectors, sensors, and mechanical devices designed to handle and dispose of exhaust fumes resulting from the engine’s combustion process.

Exhaust System

The exhaust system safely routes toxic gas to the rear of the vehicle, away from the passengers and driver. It also muffles the noise of your engine operating and helps control emissions through the use of catalytic converters.

Components of Exhaust System

  • Exhaust Valve and Piston: Engine parts that force exhaust fumes out from the combustion chamber (where they are created) to the exhaust manifold.
  • Exhaust Pipe: Carries the cleaner exhaust gasses to the muffler.
  • Tailpipe: Where exhaust leaves your vehicle.
  • Exhaust Manifold: The path from the piston to the catalytic converter.
  • Muffler: Reduces the noise of combustion and expulsion of exhaust.
  • Catalytic Converter: Converts some toxins to carbon dioxide (CO2) and water for cleaner emissions — though the exhaust is still poisonous in confined spaces (and CO2 is a greenhouse gas).
  • O2 Sensor: Oxygen sensors are positioned near points in the exhaust system so to determine if there are rich or lean mixtures in your car. Typically, an O2 sensor creates a voltage due to a chemical reaction resulting from off-balanced gasoline to oxygen ratio

Symptoms of Exhaust Leak

As the exhaust leak occurs, your vehicle generates one of the below-given symptoms:

  1. Higher engine sound than usual
  2. Clicking or tapping sound
  3. Unusual noise when accelerating
  4. Poor fuel efficiency
  5. Unusual odor
  6. Vibrating gas pedal
  7. Poor engine performance
  8. Check engine light illumination
  9. Failed emission test
  10. Visible defects
  11. Exterior carbon buildup

1) Higher Engine Sound Than Usual

The higher engine sound than usual is one of the most common symptoms of the exhaust leak.

You will find one or two mufflers that are heavily reducing the engine sound on your exhaust pipe.

If the exhaust leak occurs before one of these mufflers – the sound will not be silenced by the mufflers because it will flow out before them. This will cause a higher engine sound, depending on how large the exhaust leak is.

 2) Clicking or Tapping Sound

A leaking exhaust manifold will often produce a clicking or tapping noise. Frequently, the noise is more audible during a cold start. The noise may decrease or vanish when the engine heats up and expands the exhaust manifold.

3) Unusual Noise When Accelerating

It is normal to hear a small roaring sound when you step on the gas pedal to accelerate the vehicle. This is the sound of the engine spinning its components and generating the necessary power to push the vehicle faster.

But if you are hearing strange noises that you don’t normally hear, this could be an indication that you have exhaust fumes leaking from the system somewhere. You should be able to tell the difference between sounds coming from your exhaust and sounds coming from your engine.

4) Poor Fuel Efficiency

The fueling system in your vehicle uses oxygen sensors to determine whether your car is running rich (too much fuel), lean (not enough fuel), or stoichiometric (correct balance of air and fuel).

The oxygen sensors are located in the exhaust system. A leak before an oxygen sensor can make it appear as if the car is running lean.

With a leaking exhaust system, the engine control unit cannot get an accurate reading from the O2 sensors about how much oxygen is coming and going from the valves. Because of this, the engine will burn more fuel to compensate for this.

5) Unusual Odor

Not all exhaust fumes are odorless, just carbon monoxide. If you have a leaky exhaust manifold, you will notice a very strong odor inside or outside your vehicle. If the odor persists, then it is clearly harmful exhaust emissions that you don’t want to breathe in for very long.

Therefore, take your vehicle to an auto repair shop asap and have them verify the problem and then fix it. Make sure you drive with your windows open. Don’t take any chances with carbon monoxide because it can be lethal.

6) Vibrating Gas Pedal

You may have an exhaust leak if you step on the gas pedal and feel vibrations going into your foot. The faster these gases escape, the more shaking that will be felt.

You may feel the vibration from the floorboards and steering wheel. It will eventually get to the point where the vibration can be felt inside the entire cabin.

7) Poor Engine Performance

An engine runs optimally when exhaust flow is uninterrupted. An exhaust leak causes a drop in back pressure, which can lead to a decrease in power and sluggish acceleration. A loss of power can be attributed to many potential issues.

If you notice a loss of power in addition to some of the other symptoms on this list, an exhaust leak may be to blame.

8) Check Engine light illumination

The latest car models have sensors on the exhaust system to measure the fuel mixture escaping from the engine. One of these sensors also measures the efficiency of the catalytic converter. These sensors are known as O2 or Oxygen Sensors.

If you have an exhaust leak before one of these sensors – it will cause them to measure faulty values, and the powertrain control module (PCM) will recognize this.

As your PCM identifies a problem with your exhaust sensor, it triggers the check engine light, and your check engine light starts illuminating on your car dashboard.

9) Failed Emission Test

In some states and countries, you must do a yearly emission test to pass the inspection. If you have an exhaust leak anywhere on the exhaust system, it will affect the emission test.

If the leak is before the O2 sensors, it will mess with the air-fuel mixture, and if the leak is after these – the emission test will show a too lean mixture, and you will fail the test, depending on the size of the exhaust leak.

10) Visible Defects

The studs, screws, or nuts that secure the exhaust manifold towards the cylinder head might rust and disintegrate over time, resulting in a leak. A deformed exhaust manifold might also cause the bolts to over-extend and snap off.

Also, black stains and burned components around the source of the leak are indications of a leaking exhaust manifold. You may also notice apparent fractures in the exhaust manifold during a visual inspection.

11) Exterior Carbon Buildup

When you’re searching for the source and location of the leak, keep an eye out for black spots. If the exhaust is escaping, carbon particles might build up around the leak.

Causes of an Exhaust Leak

Multiple causes lead to an exhaust leak, but the following are the most common causes:

  1. Corrosion
  2. Damaged gaskets
  3. Physical impacts
  4. Age of the exhaust system
  5. Poor welds
  6. Driving conditions
1) Corrosion

Your exhaust spends its entire life staring at the ground. It gets hot, it gets cold, it faces rain and snow, it’s buck-shot with gravel, it’s sprayed with road tar, and it bathes in other car’s leaked oil. Stainless steel can take a lot, but eventually, your exhaust is vulnerable to corrosion.

2) Leaked or damaged Gaskets

Gaskets, such as the ones found between the manifold and the engine, can degrade over time and create uneven surfaces that allow for leaks.

Read More: Symptoms and Causes of blown Gasket

3) Physical Impacts

Your exhaust is under the car, and not everybody drives on perfectly smooth pavement. Potholes, or other road hazards, could cause damage to the low-hanging exhaust system. It also might get hit with rogue road debris.

4) Age of the Exhaust System

Everything fails eventually. An old exhaust system is one of the most common causes of an exhaust leak.

5) Poor Welds

If somebody previously repaired the exhaust and did a poor job, it could result in new leaks.

6) Driving Conditions

Driving on rough roads can cause your exhaust system to be subject to shaking and bumps that can cause holes and structural components to weaken, while rust and corrosion damage in exhaust system parts are perfect places for exhaust leaks to form.

How do to fix an exhaust leak without welding?

Follow the below given four different methods to stop an exhaust leak without welding:

1) Cover the Hole with an Aluminum Patch

You can use an aluminum patch to cover holes of any size. Once you examine the extent of the damage, use a pair of heavy-duty scissors to cut a slightly larger aluminum patch.

You may only need to cut a small piece of aluminum for small holes. With larger areas, wrap the aluminum around the pipe for effective sealing.

Cover the area around the leak with epoxy. Apply enough to seal the patch but not so much that it drips into the exhaust pipe.

Depending on the damage, place the patch directly over the leak or wrap it around the exhaust pipe. Afterward, use a wooden dowel to apply epoxy along the edges of the patch. If you wrap the patch all around the pipe, secure it on both ends with hose clamps.

2) Apply an Epoxy Bond

If the hole is small enough, you can use epoxy to seal the leak. Once you clean the surface, stir the epoxy to mix it evenly before applying it on and around the hole. You can use a wooden dowel to spread the sealant around the affected area. 

3) Use an Exhaust Clamp

If the hole or damage is not extensive enough, you can cover it using an exhaust clamp. The process is straightforward. You only need to wrap the clamp around the whole, fix the bolts, and tighten them down to cover the hole. 

4) Wrap it with Exhaust Tape

An exhaust tape is ideal if you are dealing with a larger hole. Wrap the tape around the hole, making sure to extend it a few inches on either side.

Cover the hole with at least two layers of tape for effective sealing. Since different exhaust tapes require different methods of application, make sure to read the instructions beforehand.

Repair Cost of the Exhaust Leak

The repair cost of the exhaust leak varies according to the nature of the leak and the labor cost. The average exhaust leak repair cost is usually from $90 to $810.

Below given table shows the average repair costs for exhaust leak repairs. These prices include part and labor costs.

Front Exhaust pipe replacement$140 to $610
Whole Exhaust pipe replacement$290 to $1220
Exhaust braided flex pipe$90 to $310
Catalytic Converter replacement$390 to $1600
Exhaust Pipe welding$25 to $120
Exhaust Joint replacement$25 to $210
Catback Exhaust replacement$140 to $610

FAQ Section

What is the function of an Exhaust System?

An exhaust system performs the following three primary functions: 

  • Funnel exhaust gases away from the driver and passengers.
  • Quiet the noise created by the internal combustion process inside the engine.
  • “Clean” the exhaust fumes of gases that are harmful to humans and the environment.

Does an exhaust leak affect gas mileage?

A leak in an exhaust system affects not only the health of its driver and passengers but also the fuel consumption rate and engine performance. If your car’s exhaust has a leak, this will have an impact on the pressure in the exhaust system, reducing fuel economy and leading to higher emissions.

Can I drive with an Exhaust Leak?

It is not recommended to drive your vehicle with an exhaust leak because it is harmful to both you and the environment. There is also a risk that your car will catch on fire if you are unlucky.

The safety of the vehicle will depend greatly on what’s causing your exhaust leak. As already stated, exhaust fumes can be harmful if you’re exposed to them for a prolonged period of time. 

Exhaust fumes are very hot, and sometimes the fuel in the exhaust pipe gets ignited. If you are unlucky and have the exhaust leak at an unappreciated place, it can cause your car to catch fire.

Does an Exhaust Leak Throw a Code?

It might, depending on where it is. If the leak is big enough to affect something like oxygen levels, it will spring that code.

How long can I drive with an exhaust leak?

Unfortunately, the answer is “as long as you live“. An exhaust leak can be very dangerous, and if you must drive it to get it serviced, open the windows so that you have as much fresh air coming in as possible.

What an exhaust leak sounds like?

Increased engine noise is a common sign of an exhaust leak. Listen for a loud rumble, especially while accelerating. You may also hear intermittent popping or hissing noises while the engine is running.

Does an exhaust leak affect performance?

An exhaust leak can affect the performance of your engine. You may notice that your vehicle doesn’t have its usual pick-up-and-go when you punch down the gas pedal. Your vehicle will continue to lose power if the exhaust leak isn’t fixed.

What are exhaust leak effects?

  1. Check engine light illumination
  2. Poor fuel economy
  3. A reduction in the engine performance
  4. Increased engine noise
  5. Failed emission test
  6. Clicking or tapping sound
  7. Unusual noise when accelerating
  8. Unusual odor
  9. Vibrating gas pedal
  10. Failed emission test
  11. Visible defects
  12. Exterior carbon buildup

Can an exhaust leak damage the engine?

In a worst-case scenario, an exhaust leak in the wrong place can lead to painfully expensive internal engine damage. When your exhaust plumbing carries fumes away from your engine, it’s doing more than just transporting harmful chemicals.

How do you tell if your intake manifold has a leak?

If you notice one of the below-given signs, it means you have an intake manifold leak:

  1. Check engine light illumination
  2. Poor fuel economy
  3. A reduction in the engine performance
  4. Increased engine noise
  5. Failed emission test
  6. Clicking or tapping sound
  7. Unusual noise when accelerating
  8. Unusual odor
  9. Exterior carbon buildup
  10. Visible defects
  11. Vibrating gas pedal
  12. Failed emission test

What problems does a leaky exhaust manifold cause?

If the exhaust manifold leaks, gases may escape into the atmosphere without being converted into a less dangerous gas. Consequently, you may detect an odd odor emanating from the engine bay. Additionally, leaks might result in a decrease in engine power.

Is JB Weld good for exhaust leaks?

In the case of an exhaust or muffler leak, JB Weld is an excellent choice. ExhaustWeld Total Exhaust Repair Wrap is a high-strength fiberglass wrap impregnated with a specially formulated resin for high-temperature-resistant repairs.

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