The intake manifold is one of the most important components in the car’s intake system. Here, the component ensures that each cylinder is sufficiently supplied with the necessary mixture of fuel and oxygen. Find out now how a defective intake manifold can be noticed, when it is worth changing or cleaning it, and why a simple seal can be responsible for the defect.

Function of the intake manifold in the car

In internal combustion engines, an intake manifold provides the connection between the cylinder head and the components of the mixture preparation system. Here, the component, also known as the intake manifold or intake spider, has the function of conducting the gas to the combustion chambers. In modern engines, exhaust gas recirculation, a valve or swirl flaps can be integrated into the intake manifold.

Problem with the intake manifold – change or clean?

If there are problems with the intake manifold, the question often arises: change or clean? That depends on the type of defect. If the intake manifold is cracked or otherwise damaged, cleaning it will not help. The only thing that helps here is replacement with a suitable spare part, as repair is often not possible.

Clean intake manifold

In the case of a dirty intake manifold, the degree of contamination and its construction sometimes determine the further course of action. Particularly in the case of heavy soiling due to recirculated exhaust gas, it may be worthwhile to replace the entire intake manifold. If the intake manifold contains swirl flaps, cleaning is often complicated. Some specialist companies offer professional overhaul and cleaning of all intake manifolds.

Typical symptoms of a defective intake manifold

If the intake manifold is defective, typical symptoms often appear. For example, a cracked intake manifold or a defective gasket often cause the engine to draw unwanted air. This so-called secondary air means that the ratio of air to fuel is no longer correct.

Engine runs rough due to defective intake manifold

A defective intake manifold often leads to rough engine running. The poorly running engine also makes itself felt through reduced acceleration. The driver of the car often first notices the defect in the intake manifold through a loss of power. When stepping on the accelerator pedal, the engine does not pull through well and generally does not accelerate well.

Fluctuating engine speed and unusual intake noises

In addition to the symptoms mentioned, a dirty or cracked intake manifold can also cause vibrations due to poor engine running. A fluctuation in the engine speed can also be an indication of the defective intake manifold. If the damaged intake manifold draws unwanted air, whistling noises often appear from the engine compartment.

Symptoms of a defective intake manifold in overview:

• Engine runs out of round
• Noises from the engine compartment
• Acceleration is reduced
• Engine power loss
• Motor speed fluctuates
• Intake manifold is visibly cracked

Causes for defects on the intake manifold

Various causes can be responsible for a problem in the intake manifold area. A common cause of the defective intake manifold is the stresses caused by temperature fluctuations and heat. In the engine area, the manifold is exposed to increased temperature, which leads to wear. Rapid temperature changes promote cracks.

Pollution due to recirculated exhaust gases

If the exhaust gas from the engine is returned to the intake pipe in modern vehicles, the pipes can become dirty or even clogged. The reason is the combustion residues and oil components contained in the exhaust gas. This coking, which occurs especially in diesel engines with an exhaust gas recirculation valve, is difficult to remove.

Defective gasket on the intake manifold

The intake manifold itself is not always cracked when too much combustion air and thus too much oxygen gets into the cylinders. More often, the intake manifold draws air because the component’s gasket is worn. The intake manifold gasket, made of plastic or rubber, can become warped or even brittle due to ageing and heat. This makes the gasket the invisible cause of too much air being sucked in.

Causes for a defect on the intake manifold at a glance:

• Wear due to heat
• Material fatigue of the pipes
• Seal is brittle and porous
• Damage due to vibrations
• Pollution due to recirculated exhaust gas

Changing the intake manifold

If, after a thorough diagnosis, it turns out that the intake manifold is defective, the component should be replaced. Parts of the intake system such as the intake manifold, intake manifolds or an intake spider are difficult to repair. It is often worthwhile to buy a good used intake manifold instead.

The procedure for changing the intake manifold can vary depending on the vehicle and the engine installed. Experienced car mechanics like to repair these parts in the intake tract themselves in order to save costs.

Replacing the intake manifold in a few steps

1. Prepare for replacement: Before changing the intake manifold, some preliminary work must be done. Depending on the model, this may include first removing the air filter or the air supply line. Any electrical connections and other connecting hoses must also be disconnected.
2. Removing the intake manifold: The next step in the repair is to remove the intake manifold or the intake manifold. To do this, loosen all the screw connections of the component in the engine compartment. The intake manifold can then be removed.
3. Prepare installation: Next, prepare the installation of the new intake manifold. If the intake manifold is not supplied with gaskets, insert one more gasket per duct. For used intake manifolds, each gasket should be replaced with a new gasket.
4. Install the intake manifold: The last step is to install the intact intake manifold. To do this, reverse the assembly procedure. For the purpose of diagnosing other faults in the engine, however, take a look at the intake ducts on the cylinder head beforehand. After installation, all components such as the air filter are refitted and the engine is tested.

Top guides

• Injection system in the car explained simply - parts and function of the injection...
• Maintenance and repair of electric cars: what can your normal garage do?
• Increasing performance with chip tuning: benefits, risks and tips
• Guide: Computer systems and software in your car
• Which electric car parts need repair or replacement most often?
• What is a solid-state battery for electric cars?
• All about engine sensors: from combustion engines to electric cars
• Increase the range of an electric car: How every electric car gets further
• Electric car battery life: How to extend the life of the battery
• What is the compression of a car engine?
• This is the cubic capacity of a car engine
• Internal combustion engine valves: function, defects and repair
• Core components of the internal combustion engine - parts and functions
• Engine lubrication in cars: components, function and defects
• The environmental impact of manufacturing new car parts
• All about pollutant classes and their role in environmental protection
• Engine overhaul: What is an engine overhaul and how much does it cost?
• OEM car parts manufacturing: the key components of the sector
• Understanding engine power - insight into the technology of the car engine
• The steering system of the car - structure and operation
• The car's braking system - structure, parts and function
• Engine types in the car: V-engine, in-line engine and boxer engine explained
• 8 tips before buying a used electric car
• Distinguish OEM parts, aftermarket and counterfeit car parts
• The EPC indicator light is on or flashing: What to do?
• Master brake cylinder: function, defect detection and repair
• OEM car parts for hybrid and electric cars
• Used youngtimer and classic car parts - the best tips
• Cruise control: Function and repair of the cruise control system in the car
• Exhaust system: Everything you need to know about parts and function of the exhaus...
• Locking system: security and reliable locking on the car
• The engine's air intake system - parts, function and replacement
• Brake caliper defective? How to replace it yourself
• Fuel system: parts of the fuel supply from the tank to the cylinder
• Air conditioning system: function and components of your car air conditioning syst...
• The clutch: structure and function explained simply
• Detecting and replacing a defective fuel pump
• Surprised? So many pumps work in your car
• The most common causes of a defective electric car
• The 6 most important safety components of your car
• Identify and repair a defective starter in a flash
• 5 common chassis problems and how to fix them
• 10 unknown car parts that many drivers do not know about
• Engine cooling: function and important components of the cooling system
• Differences between petrol and diesel engines
• All-wheel drive: How the mechanics and components of all-wheel drive work
• Engine control unit car: Everything about components and functioning
• Defective engine control unit: causes, symptoms and repair
• HP vs. torque: What is the difference between power and torque?
• EV motors basics: How are they built, how they work and differ from combustion eng...
• The chassis: overview and function of all suspension components
• Used electric car parts: What to look out for
• The importance of the chassis number when buying used car parts
• ABS pump defective? Function, repair and replacement
• Injection nozzle defective? Diagnosis, cleaning and changing the injection nozzles
• Alternator defective? What symptoms occur and when to change the component
• Water pump defective? Symptoms and how to repair or change it
• Steering gear defective? What are the symptoms and when should the component be re...
• Lambda sensor defective? What are the symptoms and can I clean the sensor?
• Defective air conditioning compressor - what are the symptoms and when should the ...
• Intake manifold defective? Replace gasket or clean manifold?
• Exhaust manifold leaking? Symptoms of a defective exhaust manifold or gasket and w...
• Turbocharger defective? Repair or change?
• Servo pump defective? What symptoms occur and when you should change the part
• Clutch broken? - These symptoms indicate a defect in the clutch
• Common problems and repair of defective drive shafts
• Causes of engine noise and what to do about it?
• What can car diagnostic devices do and do I need an OBD scanner?
• When and how to replace brake discs and brake pads
• Brake warning lamp lights up - causes and what to do?
• EGR valve defective: Avoid engine problems and clean EGR valve
• Improve fuel consumption: How your car uses less fuel
• Squeaking brakes: Why brakes squeak and how to get rid of it
• Safely jacking up a car: How to jack up a car using a jack and jack stands
• How a defect in the muffler becomes noticeable and how it is replaced
• E-car motor: These electric car parts you can replace yourself
• Engine overheated: What you should do if the engine overheats
• Engine check lamp lights up: What you should do as a motorist
• The engine code: What does the code mean and where can I find it on the car?
• Tools for car repair: These 10 tools you should own
• Car repair mistakes: These are the 7 most common car repair mistakes
• The gearbox code: What does the code mean and where can it be found on the gearbox...
• Used parts: How to check the quality of used car parts
• Vehicle transmission: What is the difference between manual and automatic transmis...
• Mileage: This is how mileage affects used spare parts
• Car recycling: What happens to the car when it is recycled? 
• OEM original parts or aftermarket: these are the differences 
• Advantages and disadvantages of new and used car parts
• Starting problems? Top 9 reasons why your car does not start
• What’s that smell from my car? Top causes and cures
• Advantages of shopping scrap car parts online vs. going to the local breaker yards...
• 10 most frequently purchased car parts from car breakers/junkyard
• Important car parts and their function
• Common car engine problems: Diagnosing, Troubleshooting and Fixes
• Best tips for setting up your own home car workshop
• 7 Car parts replacements and repair tasks you should not do yourself
• DIY Car Maintenance and Repair Tasks
• Guide: How to Maintain and Protect Your Car Engine
• Best practices for Engine Rebuild
• Common Causes of Rear Differential Noise, troubleshooting, and how fix it
• Common Causes of power steering noise and how fix it
• Your Guide to Car Engine Components and Functions
• Licence plate and VIN information
• Top 10 of the most popular brands in second-hand autoparts
• France is just so cool