Symptoms of a Bad or Failing Exhaust Manifold Gasket | Autance

It may not be one of the coolest systems on a vehicle, but the exhaust system is one of the…

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Symptoms of a Bad or Failing Exhaust Manifold Gasket | Autance © Symptoms of a Bad or Failing Exhaust Manifold Gasket | Autance

It may not be one of the coolest systems on a vehicle, but the exhaust system is one of the most vital. By collecting and removing exhaust gases, not only does the exhaust system help the engine to run smoothly and efficiently – the engine actually wouldn’t run at all without a well designed and implemented exhaust system.

That is why when a part of the exhaust system begins to fail it can have a huge knock on effect on your car. When a key component like the exhaust manifold gasket starts to fail, you are going to notice a load of symptoms. Being able to recognize these symptoms can save you a lot of time and money by allowing you to highlight the fault and repair it quickly.

In this article we are going to give you the tools to do just that.

What is an Exhaust Manifold Gasket?

But first, if you’re going to know if it’s gone wrong, then you probably need to know what the exhaust manifold actually is, right?

The exhaust manifold gasket is a very tough component that is essentially the very first part of the vehicle exhaust system. As you probably know, your vehicle – whether it is a car, truck, minivan or motorbike – probably operates with an internal combustion engine under the hood. If your car is all-electric by the way, it has no exhaust manifold gasket and this article is not for you!

For most of us though we are burning gas (or Diesel) in a traditional, internal combustion engine. That means that our engines work by having thousands and thousands and thousands of tiny explosions over and over in the cylinders within our engines. Each of these tiny controlled explosions generates the power that moves the vehicle.

They also generate exhaust gases though, and that is where the exhaust system comes in. This is also the point that the exhaust manifold gasket comes in too, as it is, as we mentioned above, the very first component in the exhaust system.

So… What Is It?

Sorry, we got a little carried away there – but we love talking about cars!

The exhaust manifold gasket is a like a big valve. It connects to all of the cylinders in the engine, where it collects and funnels the exhaust gases into the exhaust system itself. See how we said it is the first component within the exhaust system itself? We weren’t joking around, huh? It is literally collecting the exhaust gases as soon as they emerge from the engine itself and starting them on their magical journey through the vehicle’s exhaust system.

So if you look at a car with a running engine, when you can see the exhaust coming out of the tailpipe, then that exhaust has already passed through the exhaust manifold gasket.

Sounds Like a Tough Job

It is, it is in fact a very tough job. Those exhaust gases are coming out of the engine at high-pressure, but also at very high temperatures too. In order to cope with this, the exhaust manifold gasket itself is very tough. For one thing the exhaust manifold gasket is almost always made of either cast iron or stamped steel.

Now, they are two materials that are as about as tough as they come, and they help to make the exhaust gasket manifold one of the strongest components on the vehicle. However, as we all know and just like your Grandpa’s hip, nothing lasts for ever, does it?

Even though it is crazy tough, the exhaust manifold gasket, simply because of the stress and workload it is put through, will eventually fail. When that happens it will need to be replaced.

But, and this is a problem with the entire exhaust system, this is not a part of the car that you see everyday or can even readily access for frequent inspections. Worse, it is not a part of the car that is full of sensors either. So even on modern, computer controlled vehicles the car itself may not even know that there is an issue with the manifold gasket.

That is bad news all round because a failing gasket is going to really have a negative impact on the overall performance of your vehicle.

The Good News!

Yes, it’s not all bad news!

Luckily, there are a few easy to spot symptoms that can help you to find out if you have a bad or failing exhaust manifold gasket.

Symptoms to keep an eye out for include:

Symptoms of a Bad or Failing Exhaust Manifold Gasket

Burning Smell

Yes, it may come as something of a surprise, but when a valve full of burning hot exhaust gasses starts to fail, you may notice this manifest as a burning smell. Crazy, huh?

As we mentioned above, the whole job of the manifold gasket is to catch and channel exhaust gases from the engine cylinders into the exhaust system to be expelled out of the tailpipe. Remember as well, just as we pointed out, those gases are hot.

The manifold gasket deals with this heat in a couple of ways. The first line of defense is the tough iron or steel construction of the gasket itself. This keeps the hot gases inside the gasket where they belong. In other words, the gasket itself gets very hot, but no gases can escape and damage any components around the gasket.

It also comes with some degree of external heat shielding built in that also helps to protect the parts of the vehicle that are found around the gasket.

When the gasket starts to fail though, those burning hot gases can escape the gasket and start to damage the car. This will manifest as a burning smell, especially prevalent when the engine has been running for a little while.

It can also present with visual indictors like smoke. If you notice a burning smell and/or see wisps of smoke coming from beneath the car, that could indicate a bad or failing exhaust manifold gasket.

Negative Vehicle Performance

A fault in the exhaust manifold can also present as negative performance in the vehicle. Some people are often surprised to discover that damage to the vehicle exhaust system can cause issues with performance. After all, the exhaust system is taking away gases after the fuel has been burnt, i.e. after the car has used them to generate power.

The truth is though that the entire engine system, from the air intake to the very tip of the tailpipe are all designed to work as an interconnected system, with all the components of that system working in harmony. So when a piece of that system, such as, oh we don’t know, the exhaust manifold gasket starts to fail, that will have an impact on the entire vehicle.

What you will specifically notice is most likely a decrease in power. When driving, this could result in a car that struggles when power demands are placed on it. For example, if you are driving up a hill you may find the vehicle is not able to tackle the incline as easily as it used to.

You may also notice that the car is not as fast to pull away from red traffic signals or stop signs as it used too either. Again, these are symptoms of a loss of power possibly caused by a bad or failing power gasket.

Finally, a fault in the exhaust system can make the engine less efficient than it should be. In practical terms, this could result in you not quite getting the same miles per gallon of fuel efficiency. So if you’re at the gas station a little more often that you used to be, it could be a good idea to get your exhaust manifold gasket checked out.

Noisy Exhaust

The final symptom is actually one that can be the easiest to spot. It is also one that can often show up as the first symptom of an exhaust manifold that is in real trouble. Essentially, when the manifold fails it can make the exhaust system nosier than it used to be.

Much, much nosier in fact!

Typically the noise will present in one of two ways, with the construction style of the gasket itself plus the way that it has failed being the deciding factor. You will typically hear either a hissing or tapping noise.

If the noise gets louder as the engine power is increased then that is a real symptom of not a failing manifold gasket, but a failed gasket that needs replacing as soon as possible.


There we have it folks, those are the symptoms of a bad or failing exhaust manifold gasket. As we pointed out, the gasket itself is a very tough component, and it won’t be a part of the vehicle that fails time and time and again.

That being said it won’t last forever, and keeping an eye out for the symptoms we discussed above will help you to know when the gasket has failed and allow you to get it replaced quickly and efficiently.


  1. How a Car Exhaust System Works – HowStuffWorks
  2. How Exhaust Headers Help Engines – HowStuffWorks
  3. Symptoms of a Bad or Failing Exhaust Manifold Gasket – Your Mechanic
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