Annoying noises coming from under your car? Vibrating gas pedal? You might just have an exhaust leak. Exhaust gas leaks may allow harmful gases to get into the cabin, and at the same time, may be taking away from engine performance and fuel economy.
In this article, we will go over five common symptoms of an exhaust leak, and whether it would be safe to continue driving before you can get the leak repaired.
What is an Exhaust Leak?
The exhaust system manages the gases produced in combustion and disposes of those noxious gases safely and responsibly, treating the gases before they finally reach the atmosphere. The exhaust system also reduces the noise from the engine that would come out of the tailpipe if left unchecked.
An exhaust leak is where there is a breakage in the exhaust system that allows exhaust gases to leak out before they reach the tailpipe. If you can identify an exhaust leak early, you can prevent damage to your vehicle. Common symptoms include:
- Some types of unusual noise, such as hissing or popping noises, come from the exhaust section.
- Some types of unusual vibration, especially under acceleration, as a symptom of an exhaust leak.
- Any illumination of the Check Engine Light is a cause for concern and may indicate a problem with the exhaust system.
- A strong odor of exhaust from the engine bay or around the vehicle.
Exhaust leaks can happen as a result of numerous issues, including:
- Corrosion. Moisture and road salt cause rust and corrosion, which is a typical reason for an exhaust leak.
- Damaged gaskets. Worn gaskets between components of the exhaust can be the cause of an exhaust leak.
- Physical damage. Road debris or simply bumping into something can lead to an inadvertent crack or hole in the exhaust system.
Avoiding addressing the problem of an exhaust leak can lead to a host of issues. The leak means that the catalytic converter will not filter pollutants from the exhaust, which will lead to increased emissions and consequently lead you to fail the smog check.
The efficiency of your vehicle drops, and the consumption of fuel will go up because the exhaust gases are out of control. Lastly, there is a safety and health concern about toxic gases leaking into the cabin area, like carbon monoxide, to the occupants of the vehicle.
Common Symptoms of an Exhaust Leak
Here are five of the common exhaust system leak symptoms:
#1. Louder Noise.
When you start your car, listen to the sounds coming from the engine area. If you hear a sound that progressively gets louder while the engine is running, it’s usually a clear exhaust manifold gasket leak.
The gasket covers the connection between the exhaust manifold piping and the engine block, and it conducts the coinciding heating and cooling cycles as the pipes.
If you don’t see any visible cracks or leaks on the piping, then look at the gasket for any marks that would indicate the start of a leak.
#2. Vibrating Gas Pedal.
Even a small leak can still vibrate your car. Even though small leaks would not give much vibration, the larger the leak, the more vibration you will notice.
The gas pedal is usually the first place you will feel these vibrations, and if you ignore it long enough, you will start to feel it in the steering wheel and possibly even the floorboards in extreme cases.
#3. Poor Fuel Economy.
Be watchful of your fuel consumption. If you begin to see that your vehicle is using much worse fuel than it normally does to drive the same distances, you have an exhaust leak.
Exhaust leaks can force your engine to work in a greater attempt to provide performance, thus removing fuel efficiency as it burns much worse fuel in that experiment. If you notice your fuel consumption becoming noticeable, you could have a potential exhaust leak.
#4. Unusual noise when accelerating.
When you push down on the gas pedal, you must listen for any noise that just doesn’t sound right. If you hear a noise resembling air leaking out or a whistling sound, it is potentially an exhaust problem.
That being said, it can be tough for an average person to distinguish different kinds of engine sounds, exhaust noises, or even that a vacuum hose is leaking. It can easily become unmistakable with so many strange noises coming from your engine.
It would only be wise to consider this symptom as validation of what you suspected, with an exhaust leak symptom, if you had already experienced another symptom of an exhaust leak before.
#5. Unusual smell.
Carbon monoxide itself does not have an odor, but not all exhaust fumes are odorless. If you have a leaky exhaust manifold, you will quickly have an extremely unpleasant odor inside or outside your car.
If you smell an odor, and it is persistent, that is an indication that you are breathing in something that can be harmful, and you should not be inhaling for any length of time.
If the smell is strong enough that you suspect an exhaust leak, then you should take your car into a repair shop right away. Let them diagnose the issue and tell them to repair it as soon as they can. Until then, you should only drive with your windows down and as little as possible.
There is no reason to risk your life and take any chances with carbon monoxide, especially in bulk. It can kill you in the right concentration.
#6. Check engine light.
Your vehicle’s exhaust system has O2 sensors that will monitor its performance. If the vehicle leaks, at least one of these sensors may detect it and take note of it somewhere by turning on the check engine light on your dashboard.
What you need to remember is that the check engine light can turn on for many reasons, and an exhaust leak could just be one of them. To help narrow it down further, it would be beneficial to use an OBD-II scanner to read the diagnostic trouble codes (DTCs) so you will know exactly what the problem is.
#7. Reduced engine performance.
An exhaust leak can affect the performance of your engine. You may lose power from the engine, especially in the gas pedal while accelerating, or have a rough idle.
This is because the leak is allowing exhaust gases to escape ahead of the gas passing (exhausted) through the catalytic converter and muffler, while creating a loss in back pressures whenever the exhaust is created. With a loss of back pressure, your car’s O2 sensors can give false readings and mess up the air-fuel mixture for your vehicle.
If your car feels sluggish and has trouble maintaining speed, especially on top of other symptoms from this list, it is more than likely that you may be experiencing an exhaust leak.
Can You Drive With an Exhaust Leak?
While it is theoretically possible to continue driving during exhaust leaks, it is not advisable to do so. Sure, noise, vibrations, and reduced fuel economy can be inconveniently annoying, but carbon monoxide is not an annoyance- it’s a serious issue.
You may think that you are relatively sheltered from harmful exhaust fumes and carbon monoxide since you’re inside the cabin of your vehicle, but the cabin isn’t airtight at all. Carbon monoxide can slowly seep through and there is much less exit than there is entry.
Some exposure to exhaust fumes can lead to exhaust headaches, fatigue, dizziness, and even death with prolonged exposure to carbon monoxide.
If you find yourself feeling any of the above symptoms, especially if you’re smelling exhaust in the cabin, you should go get inspected (with a window down for safety) at an auto repair shop or muffler shop as soon as you can.
Common Causes of Exhaust Leaks
There are many reasons for exhaust leaks. Knowing them can help you see the potential before it escalates and you have bigger, more costly repairs.
Corrosion
Corrosion over time can cause exhaust parts to rust, usually due to moisture and other things like salt. This is true for a car near the ocean or one where road salt is used during the winter.
Rust on your exhaust parts can certainly be avoided. We highly recommend rinsing the underside of your vehicle where the exhaust system lives, a couple times each month to remove the moisture, salt, and other damaging contaminants.
Make sure the system has cooled sufficiently before spraying cold water on components. For a more permanent solution, you can use high-temp paint or even powder-coat supply. Plus, you could replace your system with a stainless-steel aftermarket exhaust.
Not only will you have the best protection from rusting, but some exhaust systems look even better, sound better, and/or perform better than OEM exhaust systems.
Damage
Road debris, obstacles, or accidents can lead to exhaust damage and leaks. For example, you might run over a rock, stick, or other object that punctures or dents exhaust components.
A vehicle that is low on clearance, or is bottoming out on something like a curb, can put sufficient force to create exhaust leaks. While a minor fender bender may not seem damaging to a car, there can be subtle shifts or crushed exhaust pipes and mufflers that lead to leaks.
Additionally, loose or broken hardware on exhaust mounts can also create issues. The exhaust system is secured to the underside of the vehicle with clamps, hangers, and brackets.
If one or more of these components breaks or becomes loose due to age or stress, it can lead to sagging or rattling that leads to exhaust leaks at connection points.
Faulty Repairs/Modifications
Another route to exhaust leaks is if a repair was performed either incorrectly or with regional, sub-quality materials. A modification may be performed that creates undue stress on the exhaust system.
An example of this could be putting on headers or oversized mufflers either of which can create a significant disadvantage to any aspect of exhaust if not done properly.
How to Repair Exhaust Leaks: A General Know-How
Exhaust systems frequently have rusty metals and at least one tough bolt, which requires the right tools and skill to do it right. The best option for your safety (and to lower your stress) is to have an auto repair mechanic repair.
Here is how the mechanic will generally approach exhaust repair:
Step 1: Identify the Leak
The mechanic will carefully analyse the source of the leak. They will run the engine to have enough exhaust pressure to identify the leak, spraying soapy water over the areas that ‘look’ like they’re leaking their out a few other areas too, if they see soapy water bubbling, it is leaking.
Step 2: Loosen Rusted Bolts
The mechanic will be careful to loosen all exhaust manifold bolts that have become rusted and might inhibit their repair. If a rusted bolt is being removed and is extremely obstinate, the mechanic will:
- Tighten the bolt slightly, which should release its hold.
- Use penetrating oil.
- Work the bolt back and forth to remove the stubborn bolt as long as it does not break!
Step 3: Repair Small Leak – Epoxy Bonds and Tape – (Temporary Fix)
If there are small cracks in the exhaust pipes or the manifold, the mechanic will use epoxy or tape as a temporary fix. The mechanic will clean and smooth the area of the leak, patch the area with aluminium for added strength, then wrap with exhaust tape to seal it.
If this situation is excessive, where there is large rust damage, the mechanic will replace the damaged parts.
Step 4: Replace Damaged Parts – (Permanent Fix)
The mechanic will check the damaged exhaust system parts like the muffler, exhaust pipe, and manifold. If any of the damaged parts are not repairable, they will replace these parts and reinstall the new parts to make positive secure connections.
Step 5: Cleaning the Exhaust Joints
If any of the above components were replaced, then the mechanic will need to replace the flange gaskets to make a good seal between components. To do this they will clean the area around the exhaust joint and scrape or wire brush the old gasket material off.
Step 6: Install New Gasket.
Now that the joint is clean, the mechanic will place a new flange gasket between the exhaust manifold and pipe, making sure both surfaces are smoothly aligned to avoid further leaks.
Step 7: Final Checks.
The mechanic will finally check everything, to make sure all connection and gaskets are secure and in place. The mechanic will start the engine to make sure, there are no unusual noises or exhaust gas leaks to verify the repair was successful.
Cost For Exhaust Leak Repair
The costs can be anywhere from few hundred dollars to a few thousand depending on the damage and type of part and repair needed.
The cost to diagnose the problem and leak will be $100-$200. For some repairs such as gaskets or broken pipe pieces, you can expect to pay between $200 to $350. A complete exhaust replacement can range from $800-$3000 or more.
Here is an outline of costs you can expect:
- Diagnostic cost: A mechanic will have to diagnose where the issue is and may have to do some sort of diagnostic testing that will run you about $100-$200
- Minor repairs: There are some common all parts that will be replaced, in the case of exhaust pipes breaks, broken gaskets, or exhaust pipe pieces that are broken, you can expect to pay between $200 – $350.
- Tailpipe Repair: If you were to have a tailpipe repaired (or replaced) you may be looking at anywhere from $300 to over $500.
- Muffler Repair/Replacement: If you are repairing your muffler, you may be looking at $350 to $850 for repair work and the same price for replacement.
- Exhaust Manifold: If you are getting your exhaust manifold replaced then you will be looking at anywhere from $990 to $1050.
- Catalytic Converter: When it comes to catalytic converter replacement, they will all come with different prices depending on the type of vehicle and where you are located; replacement cost can vary from $300 to over $4000!
- Complete Exhaust System Replacement: If you are doing a complete exhaust system replacement, you can expect to pay between $800 to $3000.
It is advisable to get an estimate from your mechanic or shop so you know a range of costs for which you will be looking for repairs or replacement on your specific vehicle, and how extensive the damage is.