Intake manifold: What You Need to Know

The intake manifold is an integral part of your vehicle's engine system. Its function is to distribute air throughout the engine. This makes them very important for starting your car. It distributes air to the engine's cylinders.

What is an intake manifold?

An intake manifold, also known as an air distributor or intake tube, is a part that collects intake air and distributes it evenly to each engine cylinder. For indirect injection engines, the intake manifold also collects and mixes the fuel with the air before sending the resulting mixture to each cylinder.

For all intake manifolds, a manifold gasket is installed between the manifold and the engine to ensure a leak-tight circuit. This gasket is usually made of metal or rubber for plastic intakes. A faulty gasket can cause leaks and various engine problems (misfiring, engine light, etc.).

The intake principle

Intake is the principle by which air enters the engine. Without air, the engine won't start and the pistons won't move.

To reach the engine, the air follows a precise path:

• First, it passes through the air filter, which is designed to retain as many particles as possible to prevent damage to the engine.
• Then it passes through the flowmeter, a sensor that tells the engine control unit how much air is going into the engine.
• The air then passes through the turbocharger and intercooler, if any.
• For gasoline vehicles without carburetors, the air passes through the throttle body, which regulates the air flow.
• Finally, the air enters the intake manifold.

The air filter

The intake system includes an air filter. Its job is to trap particles in the air that could damage the engine. It is one of the most frequently replaced parts on a vehicle. There are different types of air filters:

• Wet air filters: These are still found under some car hoods. They are made of foam and, as the name suggests, are slightly moist so that engine damaging particles can more easily adhere to the material.
• Dry air filters: Made of paper or cotton, they are enclosed in a hermetically sealed box. These are the filters most commonly found in vehicles.
• Oil-bath filters: These are used by a few vehicles with specific functions. They are often used in difficult terrain, such as sand.

To maintain your dry car air filter, replace it every 20,000 km or clean it with a vacuum cleaner. Wet air filters should be replaced every 50,000 km. Only the oil-bath air filter cannot be changed. To maintain it, simply change the oil every 20,000 km or so.

What is the role of the intake manifold?

The intake manifold, also known as the manifold, is a key component of an internal combustion engine. It is located between the air filter and the cylinder head. It distributes the incoming air to all the cylinders of the engine: the air is divided into several paths according to the number of cylinders present. In each cylinder, combustion takes place with your vehicle's fuel.

The shape of the manifold greatly affects the efficiency of your engine. It is made up of a series of tubes connected to a single by-pass tube with an air filter at the end. The incoming air can take two different forms:

• Made up entirely of air from outside the vehicle: it rushes into the cylinders with or without filtration;
• Mixed with cooled exhaust gas: this is made possible by an EGR (Exhaust Gas Recirculation) valve.

The operation is quite simple. When the engine is started, the air valve opens. During this intake phase, several injections are possible, depending on the fuel supply system:

• Mono injection: the air portion is supplied by the filter. The air is mixed with the fuel in the ECU;
• Multi-point injection: each manifold contains individual injectors;
• Direct injection: when the valve is lowered, the piston compresses the air in the cylinder. Direct injection only sucks in air.

What are the symptoms of a bad intake manifold?

An intake manifold failure will show up fairly quickly. You'll be able to tell if you experience any of the following:

• Excessive fuel consumption
• Cracks are visible on the intake manifold
• Fouling on the intake manifold
• Valves in poor condition
• Loss of engine power when accelerating
• Black soot deposits in intake manifold
• Intake manifold shows signs of plugging
• Deteriorated valves

Intake manifold leaks: what you need to know

A faulty intake manifold can also be the result of a leak. This will cause a number of symptoms, including the following:

• Difficulty accelerating
• Loss of engine power
• Difficulty maintaining a constant speed on the road
• Unusual engine noise
• Oil puddles under the car

Intake Manifold Cleaning

The intake manifold is essential to the smooth operation of the engine and must be properly maintained. For example, it must be carefully cleaned to prevent clogging. What's more, this operation helps extend the life of the unit. It requires the use of appropriate equipment, including a pressure washer, a stripper, and a toolbox.

First, disassemble and remove the throttle body and EGR valve. Next, remove the screws at the top and bottom of the intake housing to gain access to the manifold. Use a high pressure washer to clean the intake manifold. Apply paint stripper. Wait approximately ten minutes for the product to take effect. Rinse with water and dry.

While doing this, carefully inspect the intake seals and replace any damaged parts. All that remains is to reassemble the manifold and the other parts that were removed.