7 Symptoms of Bad Headers: Impact To Engine, Sound, and Cost

By November 7, 2022Exhaust, Uncategorized

The header is an aftermarket product, when installed in the engine, plays a major role in its proper functioning. When it fails, it comes with many symptoms you can easily notice. Some symptoms may include loss of power and increased fuel consumption, among others.  

When a problem with the header is noticed, you must have your header fixed immediately, as the leaking pipe could cause many problems and ultimately lead to engine failure. 

Personally, I have used headers, and I have had leaks in them. I noticed that my engine made disturbing sounds, and there was a bit of delay in the acceleration whenever I hit the pedal. After diagnosis, I found out my header had large holes in them, which led me to get new headers.

7 Symptoms of Bad Headers (Exhaust Manifold)

Headers are prone to get damaged because of the large amount of hot air it handles. When it gets damaged, it causes leaks and shows some symptoms, including loss of power, engine noise, and increased fuel consumption, among others.

The exhaust header is an important part of the exhaust system that helps reduce the engine’s back pressure level. The header handles a lot of hot air, which causes the header to expand when hot and contrast after cooling.  

Over time of handling these hot gasses, the metal becomes weak, and as it worsens, the metal will begin to experience cracks leading to leaks. 

Also, when your header is exposed to extremely low temperatures, there is a high tendency for the metal to crack. Like with extreme heat, metal will also expand and contrast over time from exposure to extreme cold. 

A damaged header or exhaust manifold has many symptoms, which may include, noisy engine, reduced engine performance, and poor gas mileage. 

It will be obvious if you have a damaged header or manifold because they come with many symptoms. The symptoms reduce driving experience drastically. 

1. Loss of Power 

One major symptom of a bad header or manifold is engine performance or power loss. You will notice that your vehicle does not pick up speed as it should, and the engine is always lagging. 

The engine relies a great deal on the proper flow of gasses to perform; when there is a leak in the exhaust system, the exhaust gasses will no longer be able to flow as they should. 

You can owe your engine’s loss of power to the fact that there is a  disruption air-to-fuel ratio when there is a leak in the exhaust system. Once the ratio is affected, your engine will either be running rich or lean; either way, there will not be much combustion in the engine, leading to a loss of power.    

2. Increased fuel consumption 

Another common symptom of a bad header is that your engine will begin to consume more fuel than usual. Once you notice this problem in your vehicle, you need to check your header, manifold, or other exhaust system parts.

The leak in your header will offset the balance between air and fuel, causing your engine to mix more fuel than air. You will notice that you spend more on fuel but do not know how the fuel disappears so fast. 

3. Noise from the Engine

An obvious sign that your header is bad or leaking is disturbing noise from the engine. The sound is usually either hissing or tapping sound or just both. The sound usually comes from rushing exhaust gasses escaping from the damaged or leaking area of the header.

4. Burning Odor 

When released from the engine, the exhaust gasses have extremely high temperatures; this is why they are directed to move through the exhaust pipe to their final destination where it exits the vehicle. When the exhaust gasses do not pass through the proper route, they could burn important parts of the engine and cause serious damage. 

5. Increased exhaust emission from the Cabin 

Once the header or manifold is damaged, exhaust fumes will easily escape into the vehicle’s interior, causing people to inhale harmful gasses, which could hurt their health if in that position for a while. 

The exhaust system is structured perfectly to release exhaust gasses behind the vehicle, which sends the gasses far away from getting into the vehicle. However, you can find the headers near the engine; if there leaks at that point, it is easy for the gasses to escape to the car interior.

6. Check the Engine Light

When your header is damaged, your check engine light will trigger. Your Powertrain Control Module (PCM) uses a series of sensors that monitor the engine and other parts of the vehicle; when the header is faulty, the O2 sensor will easily pick up the problem. 

Once there is a leak in the header, the problem will affect the oxygen level entering the engine combustion system, causing the sensor to notify the PCM and triggering the check engine light.

7. Obvious Cracks

When you inspect your headers or manifold, you will find visible cracks. It is important to note that this symptom is usually very hard to spot. Some cracks on the header can be very small, and you may not be able to see them. If the cracks are left unattended, they will continue to expand, making them even more difficult to fix. 

Difference Between Headers and Manifold

Before we move on, you need to understand that there is a difference between a header and an exhaust manifold. Many people do confuse them for each other, but they are quite different. 

The exhaust manifold and headers have almost the same functions and can be used in place of each other. One major difference you need to note is that the manifold comes as an original part in most vehicles, and the header is mainly an aftermarket product. 

Also, they perform the same function of directing exhaust gasses from the engine to the exhaust system for disposal. The manifold is an original part made specifically to meet the exhaust needs of a vehicle. It comes with multiple pipes that receive fumes from different parts of the cylinders and then fold or bring them all into one output. 

On the other hand, the headers have a much longer and slimmer metal tubing and are majorly used with high-performance cars like race cars because it gives more horsepower gain. The header also performs better in reducing back pressure than the exhaust manifold. 

The main difference between the manifold and the header is its structure and materials. While manifolds are made with a thicker metal steel, headers are made to be slimmer. They also have different usage requirements.  

Also Read: Long Vs Short Tube Headers: Horsepower, Sound, MPG & Tune

What Does a Bad Header (Manifold) Sound Like?

If your vehicle has a bad header or manifold, it comes with some sound disturbing to the ears. The sound may be a hissing or tapping noise. 

An exhaust header provides a medium through which many gasses can be transported directly from the engine to the exhaust system. The header has a large pipe in diameter. Once the pipe leaks, a huge amount of gas tries to escape from the leak, which causes a very disturbing noise, which is usually a hissing sound. 

The loud sound coming from your exhaust header depends on how extensive the damage or leak is. If the leak is large, you can expect a much more pronounced sound from the engine. If the damage is too small, you will have to observe before you can notice the sound.

How Do You Check for Exhaust Leaks in Headers?

To find exhaust leaks in the headers, you will have to observe and trace the sound of the noise made by the leaking exhaust. 

The symptoms of leaking exhaust in the headers would be a great way to start diagnosing your header of leaks. Unfortunately, the symptom is similar to every other exhaust leak in your vehicles, which makes it an inadequate way to diagnose a leak in the header. 

Fortunately, there is a more accurate way to check for leaks in the headers. To carry out this process, all you need to do is be very observant. 

First, you will have to start your engine and allow it to run for a while to ensure exhaust gasses have started flowing. Then, open your trunk and pay attention to any hissing or tapping sounds. 

Once you hear the hissing or tapping sound, you must get where it is coming from. Check the headers, which could be found bolted to the engine block. The multiple metal pipes are attached to the engine. If the sound is coming from the headers, you are leaking. 

To make tracking the noise easier for you, you can use tools that make finding sound easier than just observing. One tool that many professional mechanics use is the mechanic’s stethoscope. It helps you listen better and more accurately for sounds in the engine. 

If you cannot afford the mechanics stethoscope, you can improvise by using any stiff bar such as a pry bar, screwdriver, and others. Cup your hand over one side of the tool and use the other part to touch various parts of the header or manifold. By doing this, you can better track leaking sounds. 

Also Read: Exhaust Headers & Fuel Economy: Why Headers Improve Mileage

How To Repair Exhaust Headers

When your exhaust header is exposed to extreme working conditions, it can get damaged. If you want to fix it, you have to know what damage has been done to your header; with this, you can determine what type of fix it requires. The fix could be a seal or a complete replacement. 

There are majorly two types of damage that could happen to your headers, the first is a leak or crack in the headers or joint, and the second is a break or hole. 

Firstly, if the damage to your header is a leak or crack on the pipe or joint, it is easy and less expensive. What you will do is have the leak or crack sealing. There are many ways to seal a crack in the header. Some may require removing the header, while others you can do while the exhaust is still connected to the engine. 

You can weld cracks on the headers or manifold to seal up cracks or leaks properly. To start this process, you must completely remove the header and weld the crack. Do not try and weld while the header is still connected to the manifold. 

In addition, the gasket is bad if leaks come from a joint between the header or manifold and the engine. You can find a gasket between the engine and the manifold or header. You will have to change the gasket. In this case, you will have to remove the header or manifold. 

Furthermore, if the damage to the header or manifold is a break or hole in the pipes, this is a more serious problem. You will have to replace the whole header or manifold, as you cannot seal a hole in the pipe.

How Much Does It Cost To Replace Headers On Cars?

Headers are quite expensive and can cost from as low as $200 to as much as $900 without labor. Many factors can influence the price of the header. Some of these factors may include the brand of car you will use the header, labor, where you will be getting the header from, and many more.

Headers are more expensive when compared to the exhaust manifold, which will cost between  $500 to $900 with labor. Headers also need high-end fits that may increase the header’s price. You can go for cheaper bolts if you feel the header price is becoming too high, but you risk getting bolts that may not fit. 

If you are going to employ a professional mechanic to help install the header, the cost of the header may run to more than $1,000.  If you cannot afford the headers, you cannot also go for cheaper manifolds that will also fit with the original parts of your vehicle perfectly.   


Q: Does a Leaking Exhaust Manifold Affect Performance?

Leaks in the exhaust manifold will affect the performance of your engine and vehicle in general. If the problem is not fixed immediately, it could cause further damage to your vehicle.

When you leak your exhaust manifold, you will experience a reduction in the power generated by the engine. It is due to the disruption in the fuel-air mixture in the engine’s combustion system.

O2 sensors will be affected, and when this happens, the intake system may not be able to take in the right amount of oxygen to create the combustion needed to create the power. 

Q: Will a Header Leak Cause Misfire?

A leaking header can cause an engine to misfire, especially when the leak occurs before the O2 sensor. When the leak is before the sensor, the engine will run rich, leading to an engine misfire. 

The O2 sensor helps the ECM determine whether the engine runs rich or lean. Once the leak happens before the O2 sensor, the sensor might not be able to get adequate data about the airflow. It may lead to less oxygen going into the engine and more fuel. 

When less oxygen goes into the combustion system, the cylinders will be unable to produce enough power, leading to an engine misfire. 

Q: Can Exhaust Manifold Leak Cause Rough Idle?

It is highly unlikely that your vehicle will idle due to a leaking exhaust manifold, but it is not impossible. Sometimes the exhaust fumes coming from the leaks in the exhaust system can cause it to get into the intake, then your engine may idle. 

The engine needs the right amount of oxygen to create the right power to move the vehicle. Exhaust gasses will not create combustion as the gas does not contain oxygen. Once the exhaust gasses get into the intake, the engine will not be able to create the right amount of power, causing it to stall or idle roughly. 

Also, a leaking manifold could trigger a lean condition, where the ECU will increase the fuel in the engine, causing the engine to misfire and idle.  

Q: Should Headers Glow Red?

When your headers glow red, it could mean different things, which could tell a lot of things that could either be okay or not. For example, the header could glow if you hit the acceleration too hard. Also, the header means that the exhaust system temperature is too hot.

Your header can glow red when the engine is used under extreme conditions, like in high temperatures or during a race. In this condition, it is normal for the headers to be red. 

Also, your header could get hot due to your engine running lean. When the engine does not get enough fuel, it will release exhaust gasses at higher temperatures causing the header to turn red. 

Q: Do Headers Affect the Engine?

The connection to your engine can affect your engine if not working properly. The header plays a significant role in the proper functioning of the engine. When it gets damaged, it could cause the engine to lose power, rough idle, and misfire, and it can ultimately damage major parts of the engine if not fixed quickly. 

When the header gets damaged and starts leaking, it could affect the engine’s major functions, including the fuel and air that goes into the combustion system. If the mixture is inadequate, the engine will begin to idle, stall, or backfire. If this goes on long enough, parts of the engine will begin to fail. 

Ifandi L.

Ifandi L.

Passionate about everything mechanical. Ifandi has been involved with motorcycles and cars since the old days - in his family's auto parts shop. Want to keep in touch? Scream "STRAIGHT PIPEEEEE" at the top of your lungs and Ifandi will show up.

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