Which side of exhaust gasket goes to head?

Which side of exhaust gasket goes to head?

  • Author: SPELAB Mechanical Engineer (focusing on car modification for 10 years)

The side of exhaust gasket that goes against the cylinder head is usually smooth and has a very light texture. The other side of the gasket is usually rougher and has a more pronounced texture, and it faces the exhaust manifold and exhaust pipes.

It is important for us to understand the function of every component we are dealing with. Without proper understanding we are definitely going to open for ourselves a bunch of problems. In Automotive Industry, different types of gaskets are used and exhaust manifold gasket is one of the important components to experience problems.Which side of exhaust gasket goes to head

What is a Gasket?

A gasket is a mechanical seal and it fills the space between two or more mating surface, with the aim to prevent leakage. It can be manufactured from silicone, rubber, metal, plastic and many other materials, depending on its use. Previously the exhaust gaskets were made of graphite and asbestos whereas nowadays safer and more durable materials like multi layered steel or copper is used.

Function of Exhaust Gasket and its significance

The exhaust gasket serves as a connecting medium between the cylinder head and exhaust manifold or you can say it connects the cylinder head to the exhaust manifold. Exhaust manifold collects the exhaust gases from the engine cylinder and direct them towards the atmosphere via proper exhaust system. It must be noted that efficient filling and emptying of an engine cylinder is critical for smooth functioning of the engine. And, this emptying and filling of engine’s cylinders is dependent on pressure differential, because this pressure differential forms the basis for the smooth flow of gases.

As mentioned above, the pressure differential basically controls the inflow and outflow of the gases from engine’s cylinder, thus, if the pressure differential is not catered for then the flow of gases would be abrupt and your engine won’t run smooth. The negative pressure differential in the exhaust manifold pulls the gases out of the cylinder and direct them towards the atmosphere through exhaust pipes and exhaust components. To understand the importance of gasket, suppose there is a leak in the exhaust system because the gasket is not capable of producing air tight contact, then it is obvious that the pressure in the exhaust manifold would be different and alter the flow of gases. And it is understandable if the exhaust cannot move out of the engine smoothly, then the infusion of fresh air fuel mixture is also not going to be smooth and eventually the engine will not run smooth and might show following symptoms.Which side of exhaust gasket goes to head

  1. Reduced fuel efficiency
  2. Loud Noises from engine
  3. Burning smells
  4. Reduced power
  5. Reduced acceleration

Not only a worn gasket would show the above symptoms but if a gasket is installed in a wrong direction, even then the above symptoms would be shown as well as they would be more pronounced.

Direction of Exhaust Manifold Gasket

The importance of exhaust gasket would have been realized till now. As mentioned above a wrongly installed gasket would not serve its purpose and one would have to deal with problems in exhaust system and eventually the engine. To understand the significance of right direction, consider the following example

We all know that Direct Current is uni-directional and we need to be careful with terminals when working with Direct Current. If we are not careful with the direction, then either the test piece is not going to work or it might be damaged beyond repair. Similarly, one needs to be careful with the direction of the gasket. It would work only if it is installed in the right direction.

Different types of exhaust gaskets can be found in the market for different vehicles. Some are symmetric and some are asymmetric, which means in some cases we need to be careful about the direction of the exhaust manifold, whereas, in other we can ignore the direction because it will work in either direction.

With the symmetric gaskets, one doesn’t need to worry about the direction because they are engineered in the way that they will work fine in either direction. However, with asymmetric gaskets we must always pay attention to the direction of the gasket. The best way to find out about which direction goes towards the head is by consulting the instruction manual and the markings that manufacturers provide on the gaskets. Many manufacturers identify the side that goes against the head with some kind of dot or line or some other feature.

As a rule of thumb, the smooth side of the gasket normally goes with the cylinder head. It is more likely that the mating surface on the head will be flat. Less material is used in the headers or manifolds, making heat distortion more likely. Any imperfections on the manifold or header mounting surfaces are sealed by the gasket's raised regions.Which side of exhaust gasket goes to head


It is important to ensure that the gaskets are installed correctly, because if it is not correctly installed then there would be leaks and different problems with the exhaust system which will eventually hinder the overall performance of engine as it will disturb the flow of gases. If you are not sure about which side should go towards the head, then you must consult the installation instructions for the gasket and you can also check with a mechanic or professional service for guidance.

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