Our guide describes the dismantling of the entire exhaust system - using the example of a 1.8 / 2.0 liter engine - from start to finish. If individual parts are replaced, then consider only the relevant repair steps - in the V6 and turbodiesel versions of the Mondeo, do the same. Consider that screws, self-locking nuts, burnt gaskets, and brittle mounting rubber all need to be replaced.
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PROCEDURE |
- Place the vehicle on jack stands or a lifting platform.
- Support the flexible tubes first (indicated by arrows) guard or suitable support material (wooden bars, roof lathing) and clamping bands. If during installation something was twisted, then the whole «net» breaks easily, tubes can be considered scrap iron. Thus, treat them kindly enough.
- Disconnect the lambda sensor and...
- ... then dismantle the cable strand (arrow) in the body floor.
Do not kink, but support: flexible exhaust pipe in front of the catalytic converter. |
Don't forget: first disconnect the lambda sensor plug. |
- Now turn the lambda sensor (indicated by an arrow) for the flange.
- Release the flexible tube flange on the front side of the catalyst, carefully disconnect the flange and...
- ...then loosen the rear connecting flange (indicated by an arrow). Dispose of old nuts, gaskets and mounting rubber.
Tightness due to two screws: catalytic converter flange. |
- hang down «remainder» exhaust system from the mounting loops and, together with an assistant, pull the entire installation out from under «belly» Mondeo.
- Installation is carried out in the reverse order. When installing, use copper paste, rub it into the threads and new gaskets. If the unit is partially replaced, the old flange surfaces will need to be sanded. The flanges should be tightened, like the lambda sensor, with a torque of 46 Nm. Align the exhaust system under the bottom of the vehicle, test drive it and check again if all the seats are sealed.
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PRACTICAL ADVICE |
How to make sure the system is tight
Whenever an exhaust system is repaired, it is generally necessary to use new seals and screws: new gaskets are much more flexible and therefore perform better. A leaky system makes sounds not only on its own «backyard», but also has negative effects on the power and parameters of the exhaust gas. Therefore, do not forget to thoroughly work with all sealing surfaces before installation and lubricate the screw threads with heat-resistant copper paste. |
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TECHNICAL DICTIONARY |
What comes out of the exhaust system
Carbon monoxide (SO): measured during exhaust gas testing. Precise control of the injected fuel flow rate, uniform formation of the combustible mixture in the intake tract of the combustion chamber, as well as the correct ignition timing are the main prerequisites «obtaining a qualified» waste gas. Never measure CO indoors - you could burn yourself! In the atmosphere, carbon monoxide mixes with oxygen to form harmless carbon dioxide (CO2). This gas has a significant impact on the greenhouse effect.
Hydrocarbon (NS): does not burn completely «cold» places and «folded» combustion chambers. The HC component depends on the design of the engine (immutable value). In the presence of a lean or rich combustible mixture, the proportion of HC in the exhaust gas still increases. Together with nitrogen oxides (NOx) hydrocarbons are responsible for smog (heavy soluble concentration of waste gas in the atmosphere).
Nitrogen oxides (NOx): their proportion increases at elevated combustion temperatures. For example, in engines that are designed for low CO and HC (reduced fuel consumption) (engines for lean combustible mixtures). At high concentrations, nitric oxide can harm the respiratory system. Together with water, they form hydrochloric acid (acid rain).
Sulfur dioxide (SO2): It is formed as a result of the presence of sulfur in the fuel and mainly during the combustion of diesel fuel. Under the influence of light, sulfuric acid or sulfurous acids are formed. Both compounds contribute to acid rain. Modern vehicle agreements define the formation of sulfuric acids at a rate of 3%.
Typical toxins in diesel exhaust gas: Diesel engines produce exhaust gas with a low content of CO and HC, which is due to their operation. Despite the high degree of compression, they discharge into the atmosphere and less nitrogen oxides compared to carbureted engines. However, diesel should not be considered «neat», it produces other problematic combustion products, soot, for example, is a typical exhaust gas from these engines. Soot is made up of unburned carbon and ash. Particles of soot are available for inhalation and are considered carcinogenic substances. At the same time, sulfur dioxide is formed during the combustion of diesel fuel - however, in a higher concentration than in gasoline engines (see item: Sulfur dioxide). |
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