6 Symptoms Of An Exhaust Manifold Leak And Repair Cost

exhaust manifold leaking

Exhaust manifolds are vital parts in a vehicle’s engine, removing exhaust gases from the engine and reducing engine noise. But sometimes, due to some reason, the exhaust manifold starts leaking, due to which you have to face many exhaust-related problems in the vehicle.

Through this article, we will get detailed information about the symptoms of exhaust manifold leaks. So you can identify and fix your exhaust leak problem.

What Is An Exhaust Manifold?

An exhaust manifold is an important component in internal combustion engines that collects exhaust gases from the engine cylinders and directs them to the exhaust pipe. The exhaust manifold in vehicles is made of cast iron or stainless steel and is attached to the cylinder head of the engine.

In which each cylinder has its own exhaust port, but there is only one port connecting to the exhaust pipe. The main function of the exhaust manifold is to collect hot and pressurized exhaust gases from the engine cylinder and direct the collected hot gases into a single pipe, which then leads the gases to the catalytic converter and exhaust system.

The design of the exhaust manifold in vehicles can affect engine performance, efficiency, and emissions. The exhaust manifold improves engine breathing and can potentially increase power output. Modern exhaust manifolds are often fitted with integrated catalytic converters to reduce emissions. Often, the design of the exhaust manifold depends on the number of cylinders in the engine and the size of the engine head. The exhaust manifold has separate ports connected to each cylinder of the engine.

What Does Exhaust Manifold Leak Means?

An exhaust manifold leak refers to a condition where exhaust gases leak out of the engine’s exhaust manifold before reaching the system. A leaking exhaust manifold causes exhaust to seep into the vehicle’s cabin, which can be detected as an odor.

Exhaust manifold leaks can have a variety of causes, such as cracks or holes in the manifold, worn or damaged gaskets that seal the manifold to the cylinder head, or loose bolts securing the manifold to the cylinder head. An exhaust manifold leak can result in decreased engine performance, increased noise levels, and a risk of heat-related damage to surrounding engine components.

Symptoms Of An Exhaust Manifold Leak

Symptoms of an exhaust manifold leak include loud ticking or hissing sounds, increased engine noise, reduced engine performance, the smell of exhaust smoke inside the vehicle, an emissions test failure, and check engine light illumination.

These signs indicate that engine exhaust gases are exiting the manifold before reaching the exhaust system, causing poor engine operation and increased emissions.

1.Check Engine Light On

check engine light

In vehicles with modern sensors, you may see the vehicle’s cluster meter engine light illuminate when the exhaust manifold leaks. Because when the exhaust manifold leaks, the amount of exhaust gases starts decreasing. Due to this, the oxygen sensor starts sending wrong readings of exhaust gas data to the ECM. Because of this, the ECM first indicates a problem by illuminating the check engine light as a warning.

2. Smell Of Exhaust Gas

exhaust smell

When your vehicle has an exhaust manifold leak, the exhaust gases from the engine begin to leak through the manifold. when the vehicle is driven. Then you start smelling the exhaust gases along with the air flow in the cabin of the vehicle.

If you inhale these gases with breath like this for a long time, then it can be harmful to your health. One of the main symptoms of a leaking exhaust manifold is the smell of exhaust gases coming from the cabin of your vehicle.

3. Loud Engine Noise

unusual noise

The exhaust manifold reduces the engine noise of a vehicle. Due to this, the engine makes a quieter sound on startup and accelerates faster. But if the exhaust manifold of the engine is leaking, you will hear a high pitched engine noise in your vehicle.

And this high engine noise is unbearable to tolerate, this noise is much different and louder than the noise of other parts of the engine and other functional parts of the vehicle. The main symptom of an exhaust manifold leak is a loud noise produced when the engine is started or accelerated rapidly.

4. High Fuel Consumption

high fuel consumption

In modern vehicles, the engine consumes more fuel when the exhaust manifold leaks. because exhaust manifold leaks do not allow the exhaust gases to reach the oxygen sensor in sufficient quantity. Due to this, the oxygen sensor does not give the correct reading of the amount of emissions gases coming out of the engine to the ECM of the vehicle. Accordingly, the ECM increases the amount of fuel mixture in the fuel injectors.

Due to which the engine starts consuming more fuel. High fuel consumption is also a symptom of exhaust manifold leakage. However, these symptoms can also be caused by other engine problems.

5. Emissions Test Failed

emission test

Your vehicle may fail an emissions test if there is a leak in the exhaust manifold attached to the engine. Because of a leak in the exhaust manifold, not enough exhaust gas will pass through the exhaust pipe or due to incorrect data from the oxygen sensor, a high fuel mixture in the ECM fuel injectors is causing smoke content in the emissions. Due to which your vehicle may fail the emission test. However, there are many other reasons for failing an emissions test, and these reasons should be properly investigated.

Causes Of Exhaust Manifold Leak

Exhaust manifold leaks can be caused by cracked or corroded manifold surfaces, gasket failure, or loose bolts. Additionally, high temperatures and engine vibration can also be responsible for leakage.

1. Broken Mounting Studs

The exhaust manifold is fitted to the engine head with the help of nuts and bolts. With the help of these nuts and bolts, the exhaust manifold is fully bolted to the engine head, due to which the exhaust manifold does not leak. But sometimes these mounting nuts and bolts get damaged due to old age or overheating. Due to which the nuts/bolts of the exhaust manifold become loose, due to which the exhaust manifold starts leaking. Hence, these nuts should be tightened from time to time.

2. Bad Exhaust Manifold Gasket

The exhaust manifold is fitted to the engine head with gaskets to prevent the leakage of exhaust gases. so that any kind of leakage from the exhaust manifold can be avoided. But sometimes, due to overheating of the engine or due to old gaskets, the exhaust manifold gasket gets damaged and bursts. Due to which the exhaust manifold starts leaking. And the exhaust gases coming from the engine start getting out before reaching the catalytic converter.

3. Cracked Exhaust Manifold

In many cases, the exhaust manifold installed in the engine of the vehicle gets cracked. The exhaust manifold may rust and corrode due to overheating, or the exhaust manifold may crack and leak due to hitting a rock from under the vehicle. Due to this, the exhaust gases of the engine start leaking from the exhaust manifold itself. In this case, the exhaust manifold can be either repaired or replaced with a new one.

Exhaust Manifold Leak Repair Cost

On average, a 4-cylinder engine exhaust manifold gasket can be expected to cost between $15 and $30. However, exhaust manifold mounting nuts and bolts can cost anywhere from $5 to $13.

The typical independent mechanic’s labor cost can be expected to be $80 to $100. So the exhaust manifold leak repair cost can average between $160 and $300, depending on the 2- to 3-hour lead time for the exhaust manifold leak repair.

  • Parts Cost :  Gasket Cost – $15 to $30 + Nuts or Bolts Cost – $5 to $13
  • Mechanic Labor Cost : $160 to $300

The cost of parts to fix an exhaust manifold leak should be considered. Generally, the cost of an exhaust manifold gasket depends on the cylinder number of the engine in your vehicle. Exhaust Manifold Leak Repair Cost What type of exhaust manifold leak is there in your vehicle, and how easy or difficult is it to reach the exhaust manifold?

Typically, repairing an exhaust manifold leak on a car can take 2 to 3 hours. You can estimate the labor cost based on the location and experience of the mechanic. If you have experience repairing exhaust manifold leaks, Then, you can repair the exhaust manifold leak yourself. and can totally save the labor cost of a mechanic.

What Does An Exhaust Leak Sound Like?

Exhaust manifold leaks produce a distinctive and audible sound that can often be heard as a consistent, rhythmic ticking or tapping noise. This sound is produced by the exhaust gases hitting the metal surfaces. Because the leak allows the exhaust gases to escape their intended path, the normal resonance of the exhaust system is disrupted, resulting in a unique sound.


Q. Can you drive with a leaking exhaust manifold?

Driving a vehicle with a locking exhaust manifold is harmful to the engine and to the health of the driver. Because, the exhaust manifold leak badly affects the functioning of the engine, the excessive engine noise due to exhaust manifold locking will disturb you and will lead to exhaust gases in the cabin of the vehicle. And the carbon monoxide in this smoke will affect your health.

Q. How much does it cost to repair a manifold exhaust leak?

The labor cost for an independent mechanic can be expected to be $80 to $100. So the exhaust manifold leak repair cost can average between $160 to $300 depending on the lead time of 2 to 3 hours in exhaust manifold leak repair. However, you may have to shell out between $15 and $30 for parts.

  • Parts Cost – Gasket Cost – $15 to $30 + Nuts/Bolts Cost – $5 to $13
  • Mechanical Labor Cost – $160 to $300
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