The exhaust manifold collects and releases exhaust gases into the rest of the exhaust system. Since the exhaust manifold is exposed to extreme heat, they tend to warp or crack. When that happens, an exhaust manifold replacement should be performed immediately.
When replacing an exhaust manifold, a technician removes the hardware attaching the manifold to the engine, then the manifold itself is removed. On some vehicles, the engine may need to be shifted in order to gain access to the exhaust manifold. The new manifold, along with new gaskets, and hardware are installed.
The exhaust manifold should be checked periodically to detect any damage. Most manufacturers cover the cost of an exhaust manifold replacement under the powertrain warranty section of the factory warranty. It is covered under the federal emissions warranty as well. Also, an extended warranty is an option that may extend coverage of replacing an exhaust manifold beyond the factory warranty.