Symptoms of an Exhaust Manifold Leak

by Alexis Writing
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The exhaust manifold is an important component of the exhaust system. Gases from the engine are expelled through the exhaust manifold into the exhaust pipes and out of the vehicle. The manifold is connected to many small pipes, which collect exhaust fumes from the exhaust stroke via the engine's pistons. Head gaskets on the vehicle ensure that the exhaust is transferred into the manifold so that it doesn't get into other areas of the combustion system. Sometimes, however, the exhaust manifold can develop leaks.


Because the exhaust manifold is connected to other parts of the exhaust system, many of the symptoms of an exhaust manifold leak may also be symptoms of problems with other parts of this system. However, a strong odor of gas in the emissions is one major symptom of an exhaust manifold leak. This occurs because not all of the gas passes properly through the exhaust system as a result of the leak in the manifold, leading to emissions with a stronger gas smell and a higher concentration of soot.

Emissions Test Failure

If your vehicle fails to pass an emissions test, this is another major symptom of an exhaust manifold leak. A leak in the manifold causes oxygen to enter the exhaust stream, resulting in an improper mix of fuel and higher emissions. When your car fails the emissions test, the mechanic must determine whether this failure is the cause of an exhaust manifold leak or a result of other problems in the exhaust system.

Unusual Engine Sound

An unusual sound in the engine is another symptom of an exhaust manifold leak. Most often, this takes the form of a strange knocking sound near the exhaust pipe. This can be a difficult symptom to detect because it may be hard to hear the knocking sound over the regular noises of the car, especially while driving.

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