The primary work of the exhaust manifold is to gather engine exhaust gases mainly CO (Carbon Monoxide) from the engine cylinders and delivers it to the exhaust pipe. Made out of cast iron or stainless steel, it’s subject to intense heat which makes it expand and retract as it heats up and cools down subjecting it to breakage and leakage over time. It isn’t rocket science to know when an exhaust manifold is beginning to fail, the unusual loud noise from the engine is always the first sign that gives it away. But there are other effects of a bad exhaust manifold.

Please follow the link below to read more:
https://www.spotdem.com/2020/06/27/how-to-know-you-have-a-bad-exhaust-manifold/