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Your Exhaust manifold (exhaust header) worn out? » Read more about common malfunctions • Repair • Replacement manual
Exhaust manifold: defects, symptoms and replacement
The exhaust manifold is a crucial car component. A malfunction is quickly noticed. Its function, defects and how to identify them is shown in this contribution, enabling you to react timely and replace the manifold DIY or in a garage of your choice.
The exhaust manifold: function
The exhaust manifold consists of several curved cast iron pipes, collecting exhaust gases coming from the cylinders. These are directed through the manifold into the exhaust cleaning system, ultimately leaving the system by way of the exhaust pipe. Cars have an intake as well as an exhaust manifold. Defects mainly occur in the exhaust manifold as it stands under permanent high strain due to high temperatures. Cracks and ruptures are typical exhaust manifold damages. A leaking manifold is no longer able to adequately fulfill its task.
The exhaust manifold: a wear part?
Principally, the exhaust manifold is not regarded as a regular wear part. It is supposed to last a car's entire life and its performance lasts at least 80.000 km. In an average car, a manifold is therefore replaced only once in its life time, in most cases not at all.
How to recognise exhaust manifold defects
Generally, a crack or any other defect in the exhaust manifold is very quickly detected. Its signs and symptoms are very specific, such as:
- loud "rallye car" noises coming from the engine
- detectable loss of engine performance
- increased fuel consumption
- exhaust gases under the bonnet and exhaust smells in the car interior.
Replacement or repair? Which makes most sense?
Many DIY'ers swear by repairing cracks in the manifold through welding. This could be an effective measure, though damage is likely to reoccur sooner or later. In this case, choosing for replacement is the better option because only a new component guarantees long-term durability.
Exhaust manifold replacement: step by step
Even though we are happy to support DIY'ers and supply them with useful manuals, we advise against DIY exhaust manifold replacement. Its position implies difficult working conditions. Many problems in connection with the screws and stud bolts are likely to occur. Working carelessly and unprofessionally here could damage the cylinder heads, turning a potentially cheap repair into an economic total loss. Furthermore, the disassembly of the exhaust manifold depends for a great deal on its model and construction. Other components, such as the EGR-cooler or turbocharger have to be partially or totally removed, as well as the front catalytic converter. As a result, the amount of work increases along with the risk of further damage. Having the repair undertaken by a professional garage is much more effective, especially as the costs should remain within limits. In the worst case, a DIY repair attempt runs the risk of causing damage to so many other parts, that ultimately repair is no longer worth while.
These are the costs to reckon with
An exhaust manifold is not particularly expensive. Its price depends on the size of the vehicle as well as on the market situation. Generally, costs are between 100 and 450 EUR (± £90 - £400) for a new exhaust manifold and 2 up to 30 EUR (± £1.80 - £27) for new manifold gaskets. Most garages carry out this repair within two hours, bringing total costs for replacement at averagely 500 EUR (± £445). If you wish to save on the costs, by all means buy yourself a new exhaust manifold and give it to the garage for installation. This is often cheaper, as the garage is likely to add a profit margin to its own spare parts.