Four Symptoms You Have a Cracked Exhaust Manifold

What is an Exhaust Manifold? 

A vehicle’s exhaust manifold plays a huge role within the car or truck’s exhaust system, ensuring that your car stays in good condition and does not overheat. If you have a cracked exhaust manifold, then you will need a repair and need to determine the exhaust manifold repair cost, especially since this key part plays a part in connecting the exhaust port to the engine’s cylinder head and funnels the hot exhaust into the exhaust pipe.

With the help of the exhaust manifold gaskets, the manifold helps to prevent any unwanted fumes or toxic exhaust from getting into your car and harming yourself and the passengers. To keep you and your passengers safe, it is pretty imperative to the health of your vehicle and your passengers to have an exhaust manifold in good working order and keep it without a crack in it. 

The typical engine you will find in almost every single car is V-shaped, and has two exhaust manifolds attached to it. One of these exhaust manifolds is for a cylinder bank and the other is for cylinder bank two. The main amount of inline engines have just one exhaust manifold 

What is a cast iron exhaust manifold?

As we know there are two different kinds of exhaust manifolds – both of these types of exhaust manifolds can have cracked exhaust manifold repair costs that are attributed to their working parts and use over time.

Cast iron exhaust manifolds do happen to last a long time, so they might be able to prevent a cracked exhaust manifold repair cost from being too high due to these high quality parts. In modern cars, exhaust manifolds are meant to fit into small spaces and corners and live a long time to ensure that everything stays in working order within your vehicle. 

Cast iron exhaust manifolds are usually replaced with headers when the vehicle’s owner wants a pair more designed for performance and power, instead of a long-lasting and reliable exhaust manifold. Furthermore, these kinds of manifolds can be heavy and can become brittle over time with extra age. This aging and decomposition can lead to a higher cracked exhaust manifold repair cost. 

What is a tubular steel exhaust manifold? 

The second kind of exhaust manifold you will find in your car is a tubular exhaust manifold that has better flow and oftentimes found on performance types of cars, like sports cars or those with high horsepower. This style of exhaust manifold can be made from steel or stainless steel depending on what kind of manufacturer and car you have. Since mild steel is cheaper to produce, it will not last as long as stainless steel. This can lead to a more frequent and higher cracked exhaust manifold repair cost in the long run. 

Problems associated with manifold cracks and leaks

There are several problems created with exhaust manifold cracks and leaks. First, hot exhaust gases are now being vented under the hood, rather than being sent downstream through the exhaust pipe. This can damage plastic components in the engine bay. It can also become a health hazard, as the exhaust fumes can enter the car’s cabin.

There’s also the possibility that it will affect engine performance. If your exhaust manifold is cracked or leaking, the back pressure in the exhaust system will be incorrect, which can reduce engine power, cause sputtering and other problems. Of course, you won’t pass emissions testing, either.


How hot do exhaust manifolds get?

The temperature for exhaust manifolds will vary de

The temperature for exhaust manifolds will vary depending on the vehicle’s make and model. During regular operation, the exhaust manifold is usually around 300 – 600°F. However, the maximum you can expect it to reach is upwards of 1200 °F when the vehicle is under intense stress or the manifold is leaking.

If your exhaust manifold is operating above 1000 °F, there is typically a problem. An EGT gauge will help you monitor your temps.

Intake Manifold Crack Symptoms

Your car also has an intake manifold, which brings in fresh air to regulate its internal temperature and keep the engine running at peak performance. When your intake manifold is damaged or failing, you may experience the following symptoms:

  • Backfiring
  • Rough idling
  • Milky engine oil
  • Leaking coolant
  • Quick engine overheating

How Exhaust Manifolds Are Different from Headers

Many people ask what the difference is between an exhaust manifold and a header. An exhaust manifold is an OEM-style part. Aftermarket exhaust manifolds look and fit just like the exhaust manifold that came on the car when it was new, with similar flow characteristics. Like we mentioned in the “cast iron” section above, exhaust manifolds are often designed with longevity and fitment in mind, not horsepower. Headers on the other hand are designed purely for maximum horsepower and torque. They are built with steel tubing, they are often mandrel bent, and most have equal length piping so that each cylinder has similar flow. Headers can be tuned to gain more or less performance in certain areas of the engine’s power band. For maximum benefit, a full performance exhaust would be necessary when using headers, because great flowing headers are worthless if the pipes after them are overly restrictive.

Here is even more information on the topic of exhaust manifolds vs. headers.

Benefits of Exhaust Manifold Repair 

By getting this repair done and out of the way before the problems get worse, this means you will have lots of money on gas and fuel costs, and your vehicle will become more fuel efficient over time and earn more miles per gallon, saving you money and time. In addition, it also means that you will be able to protect your vehicle from additional damage if you wait too long to pay for the cracked exhaust manifold repair cost

Performance Problems

Another common symptom of exhaust issues in general is a slow or sudden loss of power when accelerating. You may notice that your car just doesn’t take off from a stoplight like it used to, or that you’re pressing the pedal much harder just to reach the next gear. A loose manifold or one with a damaged gasket tends to slowly affect acceleration power, while a crack or other sudden damage will cause an equally sudden loss of power.

Loud Exhaust Noise

A hole or lost gasket between any part of the exhaust system will naturally lead to a louder car due to the escaping sound and pressure. However, manifold damage tends to create either hissing or tapping sounds centered around the back of the engine bay. You may also hear a sound like rocks tumbling or a loud grinding if the catalytic converter was damaged by the manifold’s failure. These noises indicate your vehicle’s engine isn’t holding proper compression anymore, so avoid driving it until you can make it to the auto repair shop to prevent heat build-up from damaging other parts of the fuel and exhaust system.

Exhaust Gases in Cabin

With a cracked exhaust manifold, some of your engine’s exhaust gases will escape into the engine bay rather than being dispersed out the tailpipe. Why is this a problem? Well, your car’s climate control system pulls air from the engine bay. If the engine bay is filled with exhaust gases, some of those gases will end up inside in your car’s cabin, thereby exposing you and your passengers to potentially toxic fumes.

2. Strange Noises

If you are driving with a cracked exhaust manifold, you might hear the exhaust gases leaking out of the gasket. Depending on the pressure under which these gases are being forced out, you might hear clicking, whistling, or whooshing sounds. It’s easier to hear these sounds when your engine is cold, so listen carefully when you first start your automobile. Pop the hood, too, to see if you hear something.

What Are Cast Iron Exhaust Manifolds?

Cast iron exhaust manifolds last a long time and they are cheap to make. That is why so many cars and trucks come with them from the factory. In modern cars, exhaust manifolds are designed to fit into small spaces and live long lives. Maximizing horsepower is rarely a factor. That is why cast iron exhaust manifolds are often replaced with more free-flowing tubular designed “headers” when the vehicle’s owner is on the hunt for increased horsepower and torque. Cast iron manifolds are also heavy, and can become brittle with heat cycles and age. If they crack, the check engine light will pop on, and the vehicle will likely become embarrassingly loud. Not to mention, all of those toxic exhaust fumes would be able to escape the confines of the manifold and dance their way into the interior of the vehicle. The same thing will happen if the exhaust manifold gaskets blow out, or the mounting studs break off.


  • Warming up the problem area with a heat gun may encourage your metal repair paste to cure faster.

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  • No matter how well your patch-up works, it’s not intended to be a long-term solution. Eventually, you’ll need to either get your vehicle to a shop or learn how to replace it yourself.

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Things You’ll Need

  • 80- to 100-grit sandpaper
  • File, dremel tool, grinder, or power drill with slender bit
  • Foaming engine cleaner
  • Water
  • Liquid dish soap
  • Small container
  • Thermal metal repair paste (rated for high heat)
  • Small wooden stir stick, craft stick, or flexible plastic knife
  • 50- to 100-grit sandpaper
  • Shop vacuum (optional)
  • Wire brush dremel attachment (optional)
  • Screwdriver or similar tool (optional)
  • Hair dryer or heat gun (optional)
  • Power sander (optional)