What is the purpose of an exhaust manifold?
2 Answers
Exhaust manifolds are connected to each cylinder and eventually converge into a single pipe, allowing exhaust gases from the cylinders to enter the exhaust pipe. The exhaust manifold is also referred to as the exhaust header. The engine's exhaust system consists of three sections: the header (front section), mid-section, and tail section. The mid-section is a relatively long pipe located on the chassis, while the tail section is near the rear bumper and contains a muffler. Exhaust manifolds operate under continuous high-temperature cyclic alternating conditions. The material's oxidation resistance at high temperatures directly affects the service life of the exhaust manifold. Alloy elements need to be added to the material to enhance its high-temperature oxidation resistance.
With 20 years of auto repair experience, I often encounter exhaust manifold leaks. The exhaust manifold is the cast iron or steel pipe section that connects the engine block to the exhaust pipe. Its most critical function is collecting and channeling all the hot exhaust gases from four cylinders—its design directly affects exhaust flow efficiency. Last week, an old Tiguan had power loss due to a cracked manifold, with audible puffing leaks at idle. This component also carries the catalytic converter base, making it particularly prone to warping and cracking under high temperatures. During repairs, you have to remove the oxygen sensor before taking out the bolts, and if you're not careful, the bolts can snap inside, creating a huge hassle. Newer vehicles now use stainless steel materials, unlike old cast iron parts that become brittle over time.
