The inlet manifold, also called manifold pipe, or intake manifold in American English, is a part of the engine. It's connected to the combustion process happening in the engine. The intake manifold is physically located between the air filter and the cylinder head, which is mounted on top of the engine block which gives access to the engine cylinders and combustion chamber.
The manifold is usually made of aluminum or iron, but newer cars are equipped with a plastic intake manifold, which is a cheaper material, but also lighter. The spare part consists of a single pipe in which the air is sucked in, which then divides into several pipes. Usually there are four pipes that make up the manifold.
In the four pipes in the manifold, there are inputs from several nozzles, which make sure to send gasoline from the tank and into the manifold. Here, gasoline and air are mixed before being sucked down into the engine cylinders by the pistons.
The cylinder head is equipped with valves that open and close when the gasoline/air mixture is sent into the engine from the intake manifold. It is the mixture of air and gasoline that is important in creating the engine's combustion, which ultimately causes the car to run. The combustion happens because the oxygen acts as a combustion agent or catalyst for the combustion: Inside the cylinders the gasoline/air mixture comes under pressure when the piston compresses it. When the spark plug ignites, the explosion in the cylinders can happpen due to the presence of oxygen, which starts the combustion.
In diesel cars, however, there is no spark plug. Here the explosion in the cylinders occur by itself because a higher compression pressure is created, which make the diesel/air mixture self ignite.
But let's return to the intake manifold: The air to be used in the engine passes through several components: The air filter, air mass meter and - if your car is equipped with it - through the turbo. Then it is passed through the throttle valve and eventually it is sent into the engine intake manifold. The air is then divided between the pipes from which it, together with the gasoline, can enter the engine.
If the intake manifold is leaking, there may be a problem with the gasket. The intake manifold gasket ensures that no air slips out between the manifold and the cylinder head itself. If the gasket is worn, it can become leaky, so that the manifold does not work optimally.
If you suspect a leaky intake manifold, this will affect engine performance and cause problems with speed, engine temperature and power. In the event that you do not get a leaky manifold gasket repaired or replaced, it also wears on the cylinder head and engine pistons after some time. It is therefore important to find a mechanic who can repair the damage.
It doesn't matter if your car is a petrol or diesel car. At some point, the manifold might get dirty and clogged, especially if the air pressure is too low (this happens if you only take short trips at low speed). In this case, the combustion is not performed at its full power, which can result in more soot and particle deposition than usual in the manifold. In the long run, these deposits will clog the pipes in the manifold.
In diesel cars, however, there is even greater risk, because most cars have installed a turbocharger and an EGR valve, which can both soot relatively easy. If you have a diesel car, excessive sooting and deposit particles can be a good idea to keep an eye on.
One of the options for cleaning the intake manifold can be done with a hydrogen cleaning of the engine, including a cleaner specifically used for the intake manifold. If the pipes are not completely clogged, a mechanic may be able to perform the cleaning.
It is also possible to manually clean the intake manifold. First, it will be necessary to perform a high-pressure cleaning (by using a Kärcher for example).Then, apply a stripping product and rinse it off after several minutes.
If the intake manifold is cracked or broken, it will be necessary to change the entire part. In case you decide to carry out the replacement by yourself, you should make sure to follow different steps.
After letting the engine cool down, disconnect the car battery. Then, open the hood and remove the plastic engine cover. Unmount the air filter, as well as deconnecting the tubes, cables and sensors. Afterward, you’ll be able to access the inlet manifold. Now unmount the part with suitable tools, and install the new inlet manifold.
The inlet manifold replacement requires that you have enough mechanic knowledge, and that you own the suitable tools. Therefore, we strongly advise that you let a mechanic carry out the engine manifold change for you.
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