The exhaust manifold is a set of metal pipes, usually made of cast iron. It sits as the first part of the exhaust system, as it's connected to the engine on one side and to the exhaust line on the other by studs. The exhaust manifold's purpose is also to reduce the noise generated by combustion.
It receives the gases generated by the engine's combustion and exiting through the cylinders of the manifold. Between the engine and the manifold, a gasket is installed to make sure the transfer of gasses is sealed. It's also called the exhaust manifold gasket.
This exhaust manifold is composed of several cylinders, generally between 3 and 4, which then merge into a single cylinder.
In some cars, the catalytic converter or diesel particulate filter can be placed inside the manifold itself instead of further down the exhaust line.
In some engines (V or flat engines), dual exhaust can be found: It will send the gases through two pipes, and send them throught a dual exit exhaust. In that case, the engine will need two exhaust manifolds. On sports or high-end cars, the exhaust manifold can include 6 to 12 cylinders.
The exhaust manifold is subjected to high temperatures, especially if you are driving longer distances on highways. It expands and contracts as it heats up and cools down. After a long period of time, those temperature changes can wear the metal and lead to cracks.
If the car’s exhaust manifold is cracked, you will notice an increase in the fuel consumption, a loss of vehicle power or more noise coming from the engine.
This can sometimes result in discomfort for the car's passengers and driver, as the smell of gas can spread into the car itself.
A crack in the metal can appear on the part where the cylinders merge, or on the parts of the manifold where the heat is most concentrated.
A crack in the exhaust manifold or other sealing problems around the gasket should always be repaired. The actual spot, where the pipes merge before the exhaust system, is designed to withstand very high temperatures. However, in the event of a damage to the manifold or the gasket, we recommend that you book an appointment with a garage to prevent the damage from developing and damaging other parts of your car.
To fix a worn exhaust manifold, the mechanic will first have to unmount it in order to remove it from the engine. To do so, it is necessary to unscrew the studs. Once the exhaust manifold is unmounted, and if the crack is not too big, it can be possible to weld it.
First of all, it is necessary to clean the surface and remove the dust. Then, the mechanic will use a soldering iron to melt metal on the crack, which will fill the crack.
However, this solution cannot last indefinitely, and it can sometimes be difficault to reach the crack with the soldering iron. It will then be necessary to send the manifold to a specialist or to replace the full exhaust manifold.
| Make | Compare and save* | You save on average* | Ratings | |
|---|---|---|---|---|
| BMW | £104 | 24% |
5.0
(2)
2
0
0
0
0
Read the reviews
|
|
| Citroën | £129 | 18% |
5.0
(2)
2
0
0
0
0
Read the reviews
|
|
| Ford | £89 | 20% |
4.3
(11)
7
2
0
2
0
Read the reviews
|
|
| Mini | £89 | 21% |
5.0
(2)
2
0
0
0
0
Read the reviews
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|
| Nissan | £139 | 18% |
5.0
(3)
3
0
0
0
0
Read the reviews
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|
| Peugeot | £161 | 22% |
4.0
(2)
1
0
1
0
0
Read the reviews
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|
| Renault | £134 | 22% |
4.0
(2)
1
0
1
0
0
Read the reviews
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| Toyota | £52 | 20% |
4.7
(3)
2
1
0
0
0
Read the reviews
|
|
| Vauxhall | £158 | 19% |
5.0
(7)
7
0
0
0
0
Read the reviews
|
|
| Volkswagen | £154 | 21% |
4.8
(5)
4
1
0
0
0
Read the reviews
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|
| Make | Save on average* | |||
|
BMW
5.0
(2)
2
0
0
0
0
Read the reviews
|
£104 / 24% | |||
|
Citroën
5.0
(2)
2
0
0
0
0
Read the reviews
|
£129 / 18% | |||
|
Ford
4.3
(11)
7
2
0
2
0
Read the reviews
|
£89 / 20% | |||
|
Mini
5.0
(2)
2
0
0
0
0
Read the reviews
|
£89 / 21% | |||
|
Nissan
5.0
(3)
3
0
0
0
0
Read the reviews
|
£139 / 18% | |||
|
Peugeot
4.0
(2)
1
0
1
0
0
Read the reviews
|
£161 / 22% | |||
|
Renault
4.0
(2)
1
0
1
0
0
Read the reviews
|
£134 / 22% | |||
|
Toyota
4.7
(3)
2
1
0
0
0
Read the reviews
|
£52 / 20% | |||
|
Vauxhall
5.0
(7)
7
0
0
0
0
Read the reviews
|
£158 / 19% | |||
|
Volkswagen
4.8
(5)
4
1
0
0
0
Read the reviews
|
£154 / 21% |
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