Exhaust systems were originally supposed to "only" reduce the noise of the combustion process in the engine and release exhaust gases into the atmosphere in an orderly manner - that was the case at one time. Already in the 80s, the exhaust had another job: since then, catalytic converters have been removing up to 90% of harmful substances contained in exhaust gases. Focus is equipped with a single-section exhaust system. It consists of a regulated triple-action catalytic converter (diesel engine with oxidation catalytic converter) and a flexible intermediate part. Then, after it, the exhaust gases are released to the outside through a single-flow reflector and main muffler. Heat shields in the area of the catalytic converter and muffler prevent too much heat radiation to the lower parts of the body.
Ford covers the need for spare parts with two- and three-section service systems. When installing a service section, you cut the single-section factory system at the appropriate place with a metal saw or angle grinder. But first check whether the old muffler is reliable enough to seal the spare part with a clamp.
Exhaust system in Focus 1.4/1.6 l: 1 - catalytic converter; 2 - intermediate muffler; 3 - final muffler; 4 - gasket.
Exhaust system in Focus 1.8/2.0 l: 1 - catalytic converter holder; 2 - gasket; 3 - catalytic converter; 4 - Holder; 5 - flexible pipe; 6 - gasket; 7 - intermediate muffler; 8 - final muffler; 9 - gasket.
Exhaust system in Focus with diesel engine: 1 - catalytic converter; 2 - flexible pipe; 3 - intermediate muffler; 4 - final muffler.
The Focus' exhaust system lasts for about 70,000 km
Of course, the service life of the exhaust system depends greatly on the operating conditions of your car: if you drive mainly in urban conditions or short distances, then significantly more corrosive condensate, soot and aggressive acids settle inside the exhaust system. Exhaust systems that are well warmed up when driving on country roads last significantly longer. As a rule, the Focus exhaust system lasts about 70,000 km.
The front part of the exhaust system resists corrosion better than the rest of the system. The reason: the exhaust gases in this part still reach a temperature of 800-1000°C, so water splashes and condensation can evaporate very quickly.
On their way through the reflective and final muffler to the final exhaust pipe, the exhaust gases cool down more and more. They enter the atmosphere, depending on the operating method (diesel or petrol engine) at a temperature of about 150-300°C. Therefore, most of the condensate accumulates in the final muffler. A mixture of residual combustion products and aggressive acids gradually destroys the muffler from the inside.
Since the hot exhaust system under the vehicle is constantly subjected to a cold shower due to splashes of water, strong temperature fluctuations occur. On long journeys, they are particularly damaging to the front section of the exhaust system. This can lead, despite the flexible intermediate part (1.8/2.0 l turbo diesel engine), to smooth pipe fractures and fine hairline cracks.
Splashing water or salt water will promote corrosion from the outside. Rock strikes or other mechanical contact, such as impacts on hard ground, are equally damaging to the exhaust system, as are harmful vibration frequencies, often caused by brittle or cracked suspension rubber.