7 Signs You Have An Exhaust Manifold Leak

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leak exhaust manifold

Have you heard unusual noises from your car’s engine bay lately? How about strange emission odors? Is it performing poorly with an awful acceleration and fuel efficiency? If yes, it might be your car’s suffering from exhaust manifold leaks. And guess what, you’re on the right page if you want to learn more about exhaust manifold leaks first before you get your car touched and get fixed!

Exhaust manifold leaks result in harmful gases returning to your car rather than leaving. Fuel must be burned in the engine’s combustion cycle to provide the necessary power to run the vehicle. When fuel is burned, harmful gases are released as a consequence. After cooling and filtering, these toxic gases must exit the vehicle.

The exhaust system is in charge of cooling and purifying the harmful gases that exit the combustion system. The exhaust system directs the treated gases away from the vehicle. Any exhaust system leak might result in exhaust fumes being drawn back into the vehicle rather than expelled. If you do not immediately address the backflow of harmful gases, it might result in substantial damage.

On the other hand, the exhaust manifold gathers and transports all of the engine’s gases to the following parts of the exhaust system, where they escape via the tailpipe. Also, the exhaust manifold gasket keeps these vapors contained until they are set to be ejected. That is why a gasket must constantly be secure since a leak might harm the engine’s overall performance.

The engine of a vehicle has a plethora of intricate components. Unskilled eyes may find the engine of a mid-sized automobile or a huge truck daunting. Nonetheless, every car owner or driver must understand the fundamentals of an engine to do fixes in the event of a breakdown. An exhaust manifold is a piece that every motorist should be familiar with.

This article will discuss the exhaust manifold and its functions, what may trigger an exhaust manifold to leak, the signs and symptoms, how to repair exhaust manifold leaks, and the related repairs and costs. Continue reading to discover further ideas and details about such an issue.

Leaking Exhaust Manifold Signs And Symptoms

  • Unusual Loud Noise
  • Burning Odor
  • Noticeable Damage
  • Poor Fuel Economy
  • Weak Acceleration
  • Failed Emission Test
  • Check Engine Light

What Is An Exhaust Manifold And Its Functions?

exhaust manifold leak

The exhaust manifold is a component responsible for collecting and transporting exhaust gasses produced by the internal combustion engine to the catalytic converter. The term alludes to the manifold’s multiple inlets and exit channels that direct exhaust gasses from the engine’s cylinder head into the underbody.


The exhaust manifold is the very first piece of an entire exhaust system. The structure of the exhaust manifold and the associated pipes have a considerable effect on the engine’s efficiency and torque qualities.

Due to the integration into one of the various exhaust passages, pulsations — for example, fluctuating pressure spikes produced by one cylinder, don’t prohibit exhaust gases from getting emitted from other cylinders. Additionally, negative pressure pulses are designed to aid in getting exhaust gasses out of the engine’s cylinders.

Exhaust manifolds are frequently constructed of aluminum cast iron to resist the extreme temps generated by the exhaust. Sometimes, stainless steel manifolds are also utilized.


Exhaust manifolds are subjected to extreme thermal strain due to their position as the first equipment to transport exhaust gasses out from the engine. The material becomes weary due to the substantial expansions generated by heat and the accompanying cyclical stress created by repetitive heating and cooling cycles. As a result, this component may eventually break.

Vibrations and pulses add to the tension. Material cracks allow hot exhaust gasses to enter the vehicle compartment, resulting in undesired noise. Today’s modern materials and layouts will enable the manifold to withstand the whole lifespan of the vehicle.

Environmental Protection

The catalytic converter must promptly attain its operating temperature to guarantee minimal harmful emissions. The heat conductivity of an exhaust manifold is critical in this sense. The less mass an exhaust manifold has, the greater heat is accessible towards the catalytic converter during the initialization period.

Maintenance of Quality

Exhaust manifolds must be set following the requirements specified by the car manufacturer. Similarly, exhaust manifold gaskets should be appropriately fitted to the engine and the exhaust pipe flange that connects the manifold to the pipes to prevent exhaust manifold gasket leak through the connections while repairing the manifold.

Additionally, the downstream parts must be of good quality and in good condition and have been mounted and appropriately fastened. Extra strains, such as those induced by damaged catalytic converters, must also be addressed.

Signs And Symptoms Of A Leaking Exhaust Manifold

Exhaust manifold leaks are a pretty loud sign of a problem with your car. If left unaddressed, this exhaust leak may cause significant harm to your engine and even constitute a safety threat by allowing harmful gases into your cabin. Frequently, the problem is traced down to an exhaust manifold gasket. The manifold gasket’s function is to provide a sealing connection between the exhaust and engine cylinders.

Unusual Loud Noise

Exhaust gas and noise are emitted at high speeds directly off the engine. It runs down the exhaust manifold, then the exhaust pipes, in which it passes through the catalytic converter and eventually to the muffler until exiting through the tailpipe. This process aims to reduce the noise produced by exhaust fumes while they leave the engine.

When an exhaust manifold gasket breaks, exhaust fumes will seep via the sealing between the engine and the manifold, resulting in a loud bang or popping noise each time the cylinders ignite. This sound is sometimes mistaken for an engine knock. This is one of the foremost exhaust leak symptoms to be noticed. The two sounds distinguish the slight scream that surrounds and accompanies the popping sound. When you hear that screeching, your exhaust manifold gasket is probably ruptured.

Burning Odor

When you open the engine bay following a short drive, you might notice an awful smell of burnt plastic, oil, or rubber. While the manifold gaskets are not constructed of these elements, they have coverings that smell similar plastic, oil, or rubber if overheated and burnt. Broken manifolds do not transmit heat as efficiently as they should, leading to manifold gasket failure and aggravating exhaust leaks.

Noticeable Damage

The engine’s exhaust manifold bolts that lock the manifold might rust and disintegrate over time, resulting in an exhaust manifold leak. Additionally, a deformed manifold might cause the exhaust manifold bolts to over-extend and snap off. Also, blackened soot or burned elements around the source of the leak are indications of a leaky exhaust manifold or its gasket. Furthermore, you might notice apparent cracks in your manifold or a hanging pipe upon visual inspection.

Poor Fuel Economy

Are you hitting the gas station more frequently than you previously did? Poor gas mileage occurs when your exhaust manifold is compromised since the exhaust is no longer appropriately pressured. Not only will this result in a power decrease, but it also results in your automobile using more gas to cover the very same distance you run. Within a couple of months, a brand new replacement exhaust manifold or gasket might compensate for itself in gas savings.

Weak Acceleration

Another issue that adds to the exhaust manifold leak symptoms is a gradual or abrupt lack of power while accelerating. You might discover that your automobile doesn’t accelerate as quickly as before or that you have to push the gas pedal much more to achieve the following gear shift. An unsecured manifold or broken gasket can gradually reduce acceleration force, but a fracture or other severe damage would rapidly lose power.

Failed Emission Test

Failure to complete an emissions test is an additional significant indicator of an exhaust manifold leak. A manifold leak allows oxygen to reach the exhaust stream, leading to an incorrect fuel mixture and increased emissions. If your vehicle flunks the emission standards, the technician must assess if the failure is due to an exhaust manifold leak or different exhaust issues.

Check Engine Light

A leaking exhaust manifold could deceive your vehicle’s oxygen sensors into perceiving that a lean operating condition exists the engine’s air/fuel mixture — has insufficient fuel. Such sensors can check engine light to illuminate. In highly severe circumstances, the computer may react by enriching the air/fuel mixture to the point where performance issues such as rough idling or running and misfiring occur.

Exhaust Manifold Leak Causes

It is critical to learn how an exhaust manifold might break as they are frequently exposed to heating and cooling cycles, which means they are prone to damage. Also, more critically, to solve the problem as soon as possible. The following are the most common causes of an exhaust manifold leak:

Damaged Mounting Bolts

Most exhaust manifolds are secured using mounting bolts or studs. Numerous bolts attach additional accessory mounts inside and surrounding your engine and are connected to the exhaust manifold using nuts. When loosening these nuts, the bolts often snap.

Due to work involved in removing and replacing all the bolts that are damaged, these lost fasteners are frequently left fractured, resulting in a poor spot in the gasket, leading to a gasket breakdown. Additionally, damaged mounting bolts may cause a deformed exhaust manifold surface, resulting in fractures.

Blown Exhaust Manifold Gasket

A set of bolts and nuts locks the connection between the exhaust manifold pipe ports and engine block. This connection is sealed with a high-temp gasket and steel. A pipe flange secures an exhaust pipe to the manifold at the opposite end. Typically, the turbocharger is attached straight towards the exhaust manifold of a turbocharger-powered engine. Each of these gaskets has the potential to break, resulting in a massive exhaust leak directly at the exhaust manifold.

Cracks in the Manifold

Most exhaust manifolds are constructed of cast iron, an ideal material for dealing with the continual thermal expansion associated with heating and cooling cycles. Unfortunately, cast iron is vulnerable to cracking over time, resulting in an exhaust leak. Additionally, flanges may fracture or entirely separate, particularly at weld connections. In each of these instances, a manifold replacement is often required.

How To Spot An Exhaust Manifold Leak?

Leaks in other sections of the exhaust might resemble the signs and symptoms of a leaky exhaust manifold. And that’s why, before trying any fixes, it is critical to confirm that the leak originates from your manifold. Usually, an exhaust manifold leak can be detected by listening to the car sound and conducting a visual inspection.

To begin, switch on your engine; however, it’d be best if you do a cold start and listen for the distinctive tapping or ticking sound associated with an exhaust leak. After locating the noise source, search for evidence indicating an exhaust leak, including such soot marks and missing or broken bolts. Additionally, parts such as spark plug cables near the exhaust leak might also be burned and melted.

It may be necessary to dismantle the exhaust manifold to determine whether it has cracked in rare circumstances. After removing the manifold, physically check it for any hairline fractures that would need repair. Inspect the manifold for deformities and warps if no fractures are visible using a flashlight and a straight edge.

Begin by washing the manifold of any remaining gasket debris. Then, lay your straight edge throughout the manifold. Point the flashlight at the spot where the straight edge and manifold meet; if your manifold is deformed, the light will glow thru from beneath the straight edge.

How To Fix An Exhaust Manifold Leak?

An exhaust leak can’t stop you from running your car. However, such a leak might create significant engine problems even in the brief run.

If you have any mechanical skills, you may quickly repair an exhaust manifold leak and save money on services. However, if you lack technical understanding, it is always advisable to bring your car to a qualified technician to prevent creating more problems.

Once you’ve chosen to repair the exhaust manifold leak by yourself, there are specific particular tools you’ll have to prepare, a certain way you’ll need to ready your car, and then perform the precise fix!

  • Prepare Your Car

Repairing any exhaust component needs particular preparation before beginning the repair procedure. Since the exhaust is often searing, the first thing you should do is ensure that the automobile has cooled down. Then, disconnect the negative cable of your battery.

Following that, you must ensure that the vehicle is on a flat ground surface. Then, with a jack, lift your automobile and secure it on with a jack stand. That wraps up the first procedure for repairing the exhaust manifold leak!

  • Locate the Exhaust Leak

As previously stated, resolving an exhaust problem involves some planning. As a result, you’ll want to ensure that you address all leaks simultaneously to prevent raising the vehicle once more and repairing another exhaust leak.

Having stated that, the very first phase in repairing an exhaust manifold leak is to locate the leaks. As a warning, exhaust pipes may be pretty hot; thus, always use protective hands to prevent burns and other injuries.

  • Unscrew the Bolts

Two big bolts attach the manifold to your system. If a heat shield protects your system, you may have to search a bit to locate these bolts. Since the two bolts are often quite tightly secured, you may have to apply a wrench to unscrew them. In certain circumstances, you may need to spray penetrating oils and let them sit for around 15 minutes to unscrew the bolts.

Thoroughly unscrew the two bolts; you don’t want to ruin them or shatter the bolt heads, causing more harm to your manifold.

  • Replace the Manifold Gasket or Entire Manifold

After removing the two big bolts, you should now locate the manifold attached to the engine. If you are replacing merely the manifold gasket, don’t altogether remove your manifold off the engine. Just partially detach the manifold from the engine and extract the damaged gasket from the cylinder head. Following that, just insert the replacement gasket into the gasket slot.

If you wish to replace the whole manifold, you should remove it off the engine and replace it with the new one. Remembering how your manifold was disassembled is critical to reinstall it correctly.

Exhaust Manifold Leak Repair Cost

Generally, it takes two and three hours to fix the exhaust manifold leak. The average cost of work per hour is about $100. Thus, labor costs for fixing the exhaust manifold leak are around $150 up to $300. The expense might increase to $350 if you prefer to have the manifold leak repaired at the dealership, wherein labor is somewhat more expensive.

If you can DIY it, you will save a significant amount of money. However, this is not suggested unless you are confident in your skills. Other expenses, such as automotive components, vary according to the vehicle. Rates will vary according to your vehicle’s year, make & model—also, the number of cylinders in the engine, your location, and the shop.

Finally, the cost of fixing the exhaust manifold leak may range from as little as $20 if you DIY it and as much as $400 at the car dealership.


If an exhaust manifold leak isn’t addressed soon, your engine could suffer severe damage. A leaking exhaust manifold gasket might lead to burned exhaust valves, allowing combustion exhaust to stream back into your intake manifold.

The leak might be triggered by a gasket failure, bolt failure, or even the manifold itself. A burning aroma, strange sounds, or apparent leakage in your exhaust system might indicate a problem. Keep an eye on all mentioned exhaust manifold leak symptoms to rule out any exhaust leak or other difficulties. The earlier you identify the issue, the more quickly it may be resolved.


How serious is an exhaust manifold leak?

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 it bad to drive with a manifold leak?

It is dangerous and not recommended. A manifold leak may cause an engine to overheat by causing the air/fuel mixture to become excessively lean. Additionally, it has the potential to taint your oil, the environment, and your health!

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