What Causes Exhaust Manifold to Glow Red and How to Fix

Are you curious about what causes exhaust manifold to glow red? It is generally due to a blocked exhaust system that indicates catalytic converter failure. An exhaust manifold is a cast iron unit that collects exhaust gases at one point. For modern cars, the exhaust manifold is termed an exhaust header. The main difference between the exhaust header and manifolds is that header is of steel tube material. However, a manifold is of cast-iron structure.

Generally, the exhaust manifold doesn’t get super-hot. If it is glowing red, it shows a sign of obstruction in the exhaust or catalytic converter. This could be due to fuel and air mixing or ignition timing and other reasons. Exhaust header glowing red causes loss of fuel economy and loss of power.

In this article, I will guide you on what causes the exhaust manifold to glow red and how to fix it. Before starting let’s discuss the exhaust system and the role of the exhaust manifold.

exhaust manifold to glow red

Role of manifold in the Exhaust system

The exhaust system leads exhaust gasses away from the engine. The entire exhaust system carries toxic gasses from the engine by exhaust pipes. Depending on the structure of the exhaust system, exhaust gases move from these parts.

  1. Exhaust manifold or header
  2. Turbocharger
  3. Catalytic converter
  4. Muffler

The manifold or header’s purpose is to carry exhaust gases away from the system. In a general engine, all exhaust gasses end up in the exhaust manifold or header. Furthermore, it enhances the performance of the engine and slightly improves the sound of the car.

What Causes Exhaust Manifold to Glow Red?

The most asked question is, how hot do exhaust manifolds get? Usually, a clogged exhaust system is a significant reason for the manifold turning red. The highest temperature an exhaust manifold can reach is 1,600°F (850°C). After 500°C, it starts to turn red and at 1175 F color of the turbo exhaust manifold is cherry red.  Red hot exhaust is typical in diesel engine cars and dirt bike. It indicates that the engine is getting hot and needs proper cooling. Usually, a car engine can’t withstand extremely high operating temperatures. At high-temperature, exhaust manifold cracks and makes turbocharger failure.

 However, experts believe that the reason for the red run exhaust is catalytic converter failure. These factors cause converter damage. If you notice the below two symptoms, you may face exhaust manifold glowing red.

  1. Too late, Ignition timing
  2. Engine runs lean

1. Ignition timing is late

It means that the car is showing signs of engine knocking. Ignition timing is the critical part of running the engine. If the ignition timing is too early or too late, it damages the engine. Usually, when the ignition of fuel and air is too late, it reduces engine power and efficiency.

2. Engine runs lean

If the fuel in the engine is less and the air is a large amount. It causes the engine to run lean. When the car doesn’t have enough fuel, the exhaust manifold heats up.

Symptoms of Restricted Exhaust System

The glowing red of a manifold is one of the critical conditions of a combustion engine. Generally, lightly glowing headers in a diesel engine are not rare. The temperature of exhaust gases causes a manifold to glow to dull red. If the exhaust header is glowing red, that is a huge problem. Usually, a clog exhaust system is due to a catalytic converter failure. The catalytic converter red hot is not suitable for the engine. Let us look at the symptoms of a clogged exhaust system.

1. Reduced Engine Performance

Commonly, obstruction in the system and old spark plugs causes exhaust to overheat. Symptoms of poor engine performance are poor fuel economy, loss of engine power, loud noise when accelerating, and engine cranking. Reduced engine performance indicates a severe problem for the engine. This sign also causes the exhaust to turn red hot.

2. Lead fuel

Lead fuel is car racing fuel. It is an octane booster that provides high efficiency, reduces motor knocks, and high compression. Typically, lead petrol causes the catalytic converter to overheat.

3. Coolant leakage

Coolant removes heat from the exhaust system by transferring it through different coils. Cooling water leaking causes the system to overheat and generate white smoke from exhaust. Coolant leaks or silicon from sealant act as a catalyst which creates a white coating in the oxygen sensor. It causes the exhaust system to fail. This coating is visible when the parts of an exhaust system are removed. Coolant leakage is a serious issue for your car.

4. Bent exhaust pipe

A damaged, bent or kinked exhaust pipe restricts flow. Moreover, a physically damaged or rusted exhaust tailpipe causes the catalytic converter to fail. It acts as an insulator and causes the converter to overheat.

5. Thermal shock

 Sometimes rapidly cooling and heating of the catalytic converter creates a thermal shock. The thermal shock changes the property of the material, causing it to distort or break.

How to fix exhaust manifold glowing red

In different ways, an exhaust manifold or catalytic converter indicates the problem. One of them is by glowing red. Normally, if the catalytic converter or exhaust pipe is turning red, it should be diagnosed by a mechanic. If the problem is ignored, it can cause grave damage to the engine. Sometimes catalytic converter turns bright red due to a cylinder misfire.

Suppose you have the problem of the engine running rich or fuel not burning correctly. It can cause damage to the honeycomb material inside the converter. The exhaust pipe can be clogged and cause damage to the engine. It is not easy to repair or replace the catalytic converter on your own. Moreover, a mechanic can diagnose the problem by using onboard diagnostic tools. That is impossible to do without any expert help. Thus, solve the red exhaust manifold problem without any delay according to the detected issue with the help of the reliable mechanic. You should also fix the exhaust leak if you notice any kind of leakage of exhaust pipe.

FAQ (Frequently Asked Question)

1. Why is my exhaust manifold glowing orange?

When the metal gets hot, it emits light from the infrared spectrum. Moreover, when the iron in the exhaust manifold gets hot up to 1800 Fahrenheit’s it emits orange light.

2. Will headers glow red?

Yes, the header glows red when the car doesn’t have enough fuel and turns lean. Secondly, when the ignition timing is too late, it causes the header to turn red. The heat from these conditions causes the header to glow red.

3. Why is my car exhaust so hot?

When hot combustion gases or unburned fuel from a larger injector enter the muffler, it causes extra heat that goes through the exhaust. Sometimes temperature of the muffler reaches 1200 F.

4. Why is my catalytic converter glowing red hot?

The catalytic converter glows red because it is blocked. Furthermore, when raw fuel enters the catalytic converter and starts to burn, it causes the converter to turn red. If the cylinder misfires, it’s because of faulty spark plug or ignition coil.

5. Can a blowing exhaust cause misfire?

No, when the component of the exhaust system is damaged, it causes an impact on car performance and efficiency. However, the cause of the misfire is damaged spark plugs, ignition coils, and vacuum leaks.


Manifold is a critical part of an exhaust system. The most asked question is what causes exhaust manifold to glow red? Ordinarily, when the exhaust manifold or header turns red, the engine doesn’t have enough fuel or ignition timing is too late.

Moreover, a red glowing manifold indicates a clog exhaust system, which is mainly due to catalytic converter failure. Problem with Catalytic converter requires replacement or repair. Replacement and repair are complex tasks that need professional help.


Shafiqule Islam is a graduated Mechanical Engineer. He has both on hand and managerial job experience of 15 years in automobile maintenance field. He served as Captain in Electrical and Mechanical Engineering Corp of Army, Technical Head in Taxi Cab business, Head of Plant in Car assembly plant. He is writing automotive contents to share his expertise knowledge to car lovers for solving their vehicle issues.

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