Exhaust Manifold
A cast iron or steel pipe assembly that collects hot exhaust gases from the engine cylinders and directs them to the exhaust system.
The exhaust manifold is the first section of a vehicle's exhaust system, bolted directly to the engine's cylinder head. Its primary function is to collect the hot, high-pressure exhaust gases expelled from each cylinder and channel them into a single pipe that routes to the catalytic converter and tailpipe. It also houses the upstream oxygen sensor.
Exhaust manifolds are typically made of heavy cast iron or tubular steel to withstand extreme combustion temperatures (exceeding 1,200 degrees Fahrenheit). Because they heat up and cool down rapidly, they undergo significant thermal expansion and contraction, which puts immense stress on the manifold and its mounting hardware.
Over time, the constant thermal cycles can cause the exhaust manifold to warp, crack, or blow out its mounting gasket. Symptoms of a cracked manifold or failing gasket include a loud ticking or tapping noise from the engine bay (especially when the engine is cold), exhaust fumes in the passenger cabin, a decrease in engine power, and a check engine light caused by incorrect oxygen sensor readings.
A leaking exhaust manifold is a safety hazard because it can release dangerous carbon monoxide gas under the hood. Replacing a warped or cracked exhaust manifold restores quiet operation, exhaust safety, and optimal engine backpressure.