What is the most common reason for the failure of an exhaust manifold?

The most common reason for the failure of an exhaust manifold is frequently due to leaks in the system. Exhaust manifolds are designed to collect and channel exhaust gases from the engine cylinders into the exhaust system. Over time, the constant exposure to high temperatures can cause the materials to weaken or crack, leading to leaks. This not only impacts the efficiency of the engine by allowing exhaust gases to escape before they enter the catalytic converter but can also lead to an increase in emissions and noise.

While rust and corrosion can weaken the manifold over time, they are generally less immediate concerns compared to the critical issue of leaks, especially in regions where heat cycling and thermal expansion occur frequently. Excessive weight on the engine and improper installation can contribute to premature failure, but leaks are the most direct cause of malfunctioning exhaust manifolds that vehicle inspectors frequently encounter. Thus, understanding the commonality of leaks is essential for recognizing signs of failure in exhaust systems during inspections.