An internal combustion engine, such as the one found in an automobile, relies on the rapidly expanding gasses produced by burning fuel to propel the pistons and produce power. The process of combustion, however, carries some unwanted byproducts in the form of harmful emissions, heat, and noise. Therefore, an engine is fitted with an exhaust system to quiet down the sound of the engine and to route the engine exhaust away from vehicle occupants. The exhaust manifold gasket is a component of this system.
Your engine can produce exhaust upwards of 1,000 degrees Fahrenheit. That exhaust also contains compounds harmful to humans and the environment, such as carbon monoxide, hydrocarbons, and nitrogen oxides. The exhaust system collects these hot gasses in the exhaust manifold as they exit the engine’s cylinders. From there, the exhaust passes through pipes to the catalytic converter and ultimately to the muffler and out of the tailpipe at the rear of the vehicle.
The exhaust manifold is a large metal chamber or collection of chambers bolted directly to the engine cylinder head. Sandwiched between the manifold and the engine is a gasket, the exhaust manifold gasket, that prevents gasses from escaping the exhaust system at that junction. The gasket can be made of heat-resistant fiber, ceramic, graphite, asbestos, or steel.
The procedure to replace an exhaust manifold gasket can vary in complexity a great deal depending on the vehicle make and model - how the engine is oriented or how many other components must be removed for access. The mounting hardware for exhaust components, including the exhaust manifold, are also subject to a good deal of stress and degradation from heat and corrosion, making them difficult to remove.
To replace the exhaust manifold gasket on an engine, a technician will take the following general steps: