Car exhaust manifold - malfunctions, symptoms, exhaust manifold repair

The engine element, which is the exhaust manifold, may seem very simple, it has several problems. They depend on the design of the unit and various malfunctions may occur in individual car models. For example, in the 1.9 TDI engine of the Golf V, the exhaust manifold gasket often separated from the surface of the cylinder block. In old Opel gasoline units (2.0 16V), a crack appeared approximately in the middle of the part. Why doesn't the exhaust manifold last forever in internal combustion vehicles?

Why does the exhaust manifold fail? Key features that may be damaged

Of great importance for the performance of the exhaust manifold are the operating conditions of the entire system. Its performance is affected by:

• temperature;
• vibration from the engine;
• road conditions;
• vehicle operation.

Contact with the engine block causes this element to heat up to high temperatures. Exhaust gases passing through the exhaust are very warm (up to 700 degrees Celsius in gasoline units), which affects the expansion of the material. In addition, vibrations from the engine, variable thermal expansion of different materials (aluminum behaves differently than cast iron), the influence of changing external conditions (snow, mud, water) and, finally, the way the car is operated must also be added. . Thus, the automobile collector is prone to malfunctions from all sides. What is most often wrong with him?

Cracked exhaust manifold - why is this happening?

Big influence on it car collector breaks, comes into contact with dissimilar materials. Cast iron, from which exhaust manifolds are most often made, warms up more slowly than aluminum and steel. Therefore, especially when driving very hard on a cold engine, it may happen that the aluminum block behaves differently than the cast iron manifold. The steel exhaust manifold studs hold up well to tension, which is not the case with the welded manifold. As a result, the element breaks, as a rule, at the welding point.

A cracked exhaust manifold is a sign of breakdown and failure. When is replacement or repair required?

The easiest way to recognize a cracked manifold is to simply start the engine. The sound of its operation is different, and in some cars it turns out to be variable depending on lower or higher rpm and the degree of engine warm-up. The previously soft operation of the unit and the pleasant silence in the cabin turns into a metallic annoying sound. However, it will not always be possible to see where the exhaust manifold is damaged. Usually the reason is microcracks, invisible without disassembly and inspection on the table.

Exhaust manifold welding - is it worth it?

If you ask any "knowledgeable person" he meets, he will tell you that it can be done. And in principle he will be right, because a leaky collector can be brewed. However, the effect of such an action is not always (in fact often) bad. This is because cast iron is an extremely demanding material in processing. It is cheap and durable, but welding requires appropriate techniques.

Exhaust manifold replacement or welding?

During this process, the brittleness of the material of the welds is manifested, which can be seen when they cool. When it turns out that everything is already well cooked, suddenly you will hear a “pop” and all your labors are in vain. In addition, when welding, the collector reduces its flow, which negatively affects the operation of the unit. A one-time repair in this way is acceptable, but it is much better to buy a second part in an online store (even a used one), because the price will most likely be the same.

How about getting rid of the exhaust manifold?

Although the exhaust manifold is a factory-welded cast iron pipe, it has a very large impact on engine performance. The length of the collector itself greatly affects performance, as does the profile of the channels. Looking at this detail, you will notice that at some point it merges into a single pipe passing through the cable under the engine. A lambda probe is often placed in the exhaust cylinder to measure exhaust gas quality.

Tuners, in turn, are very willing to modify the entire exhaust system, starting with the manifold, which has a significant impact on achieving power in various rpm ranges (especially high ones). From this we can conclude that the collector cannot be disposed of.

What to do if there is a problem with the intake manifold? Symptoms are sometimes invisible to the naked eye, so it is worth contacting a specialist. A damaged manifold in a car is hardly worth repairing, so it's best if you just decide to buy a new part that the car can't do without.