Exhaust manifolds are an engine component that is found on all internal combustion engines. Exhaust manifolds are usually made of cast iron or stamped steel and are designed to collect exhaust gases from the engine cylinders and transport them into the exhaust pipes for expulsion. The exhaust manifold is attached to the engine cylinder heads and has ports that collect exhaust gases from each individual engine cylinder. Cast iron manifolds are usually one piece, while stamped steel ones are usually welded together. Both are designed to withstand the high stress and heat conditions required to trap and transport exhaust gases. While they are heavy duty in nature, they can still be prone to issues, and can cause problems with drivability when they have a problem. Usually a bad or failing exhaust manifold will produce a few symptoms that can alert the driver of a potential issue.
1. Noisy engine exhaust
One of the first symptoms of a problem with the engine exhaust manifold is an excessively loud exhaust. If the exhaust manifold cracks, breaks, or leaks, it can cause an exhaust leak that will lead to a noisy exhaust. The vehicle may produce a hissing or tapping sound from the engine bay that may get louder when the engine is accelerated.
2. Decreased power, acceleration, and fuel efficiency
Engine performance issues are another symptom that can be caused by a problematic exhaust manifold. If the exhaust manifold cracks or leaks, it can cause an exhaust leak that can negatively affect engine performance. An exhaust leak can cause the vehicle to experience a reduction in power, acceleration, and even fuel efficiency.
3. Burning smell from the engine bay
Another symptom of a problem with the exhaust manifold is a burning smell from the engine bay. If the exhaust manifold has any issue with the heat shield or exhaust leaks the excess heat can cause damage to nearby electrical and plastic components. Exhaust manifolds can reach temperatures in excess of nine hundred degrees Fahrenheit which can cause any nearby or contacted components to burn up. Burnt components may produce a plastic burning smell that is sometimes accompanied by smoke and can lead to other issues so any burning smells should be checked out to make sure that they are not a major issue.
While exhaust manifolds are usually built to be heavy duty to enjoy a long service life, they can still be prone to issues simply due to the high stress conditions they are constantly under. If you suspect that your vehicle’s exhaust manifold may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the vehicle will need an exhaust manifold replacement.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Exhaust Manifold and was authored by Ed Ruelas.