The exhaust manifold is a system of hoses which transport hot gas out of the engine cylinders into the exhaust system. This first element of the exhaust system is pinned to the engine block. As exhaust manifolds are exposed to extreme temperatures, their failure usually results from deformation or cracking. When this happens, the noise produced by the engine is much louder, both inside and outside of the car. In addition, a malfunction of the manifold may cause the fumes flowing through it to be sucked into the cabin, which is very harmful for health.
What is the role of the exhaust manifold?
The exhaust manifold collects waste gases from each cylinder and transfers them to the exhaust pipe. The manifold is attached to the engine block by means of pins. It requires changing if its tightness is compromised due to cracks and deformations.
How is the manifold replaced?
The exhaust manifold must be replaced if the engine is removed from the car. In older cars, removing the screws fixing the manifold to the engine block may be difficult as they may be corroded or stuck. A good idea is to apply a rust remover one or two days before changing the manifold to loosen the screws. Removing the manifold may require disconnecting the hoses of the turbo charger of the waste gas recirculation valve. After removing the screws the remaining part of the exhaust pipe must be disconnected from the manifold.
How is a new manifold fitted?
When fitting a new manifold, you should check its contact surface with the engine block and clean the block in this spot. A good idea may also be to use new pins and re-thread the mounting holes in the engine block. A new manifold gasket is a must. After fitting the manifold you should start the engine and check the contact point between the engine and the new part for any leaks and ensure that the engine operates quietly.
What to keep in mind?
Remember that driving with a leaking exhaust manifold is dangerous as the gases entering the engine chamber may be sucked in by the ventilation system and cause poisoning.