E30 series BMW 3

since 1983-1994 of release

Repair and car operation

+ 1. Maintenance instruction
+ 2. Maintenance
+ 3. Engine
+ 4. Cooling system
+ 5. Heating and ventilation
+ 6. Fuel system
+ 7. Exhaust system
+ 8. Transmissions
+ 9. Coupling
+ 10. Brake system
+ 11. Running gear
+ 12. Body
+ 13. Electric equipment
- 14. Good advice
   14.2. Changed numbers
   14.3. Purchase of the old car or mysterious set of figures and letters
   14.4. Durability of the car
   14.5. About parallelism of bridges of the car and the trailer
   14.6. Preparation of the car for winter
   14.7. Rule 35
   14.8. Choice of the second-hand car
   14.9. Engine oils
   14.10. That it is necessary to know, changing oil
   14.11. Emergence in deposit oil
   14.12 whether. It is possible to mix import oils?
   14.13. "Eats" much, but silently goes
   14.14. It is rather live, than it is dead …
   14.15. It is not got - good advice
   14.16. Visit to car-care center
   14.17. A gear belt for a drive of the mechanism of a gazoraspredeleniye
   14.18. Wear of pistons
   14.19. Valves
   14.20. Bearings of engines
   14.21. Engine pollution
   14.22. As the conditioner works and what to do, if it failed
   14.23. Conditioner: not only "pluses", but also "minuses"
   14.24. Rules of service of the conditioner
   14.25. It is not necessary to stir antifreeze with antifreeze …
   14.26. That it is necessary to know upon purchase of the air filter
   14.27. Engine overheat
   14.28. That it is necessary to know to the owner of the car with the injector engine
   14.29. Accumulator
   14.30. Possible malfunctions of the storage battery
   14.31. What to do with the failed generator
   14.32. The belt is guilty, and we blame the generator
   14.33. Catalyst
   14.34. Rub in one - or how to save the catalyst
   14.35. Probuksovochka
   14.36. Features of operation of brake system
   14.37. Malfunctions of brake system
   14.38. Brake liquids
   14.39. ABS: natural choice
   14.40. Rims
   14.41. We update rims
   14.42. Scheme of marking of a car tire
   14.43. Metal corrosion
   14.44. Automake-up
   14.45. What creaks?
   14.46. Hatch
   14.47. Safety cushion: troubles or pleasures?
   14.48. We fit well?
   14.49. Anticreeping "immunodeficiency"
   14.50. Why headlights grow dull
   14.51. "Galogenki"
   14.52. About the correct adjustment of headlights
   14.53. Electric motor
   14.54. From change of places "composed" changes nothing?


14.33. Catalyst



Catalytic converter of exhaust gases has the case from stainless steel to which welding attached inlet and final cones with branch pipes and fixing flanges, and also the heatreflectors holding a ceramic covering. All internal volume of the case is occupied with the ceramic porous monolith fixed by rings or a grid from stainless steel. The structure of a monolith is similar to the ordinary filter, but all internal and external surface of the time contacting to gases, is covered with very thin molecular layer of an alloy which contains platinum, rhodium and a palladium. Porosity of a monolith has the big area of the surface covered with this alloy from very expensive metals that in the basic and defines the high price of converters.

Work principle

The engine releases into the atmosphere together with exhaust gases products full (H2O water vapor, N2 nitrogen, etc.) and incomplete (WITH carbon oxide, and also CnHm, NOx nitrogen oxides) fuel combustion. Total number of components which contain in these gases, exceeds some hundreds, and the majority of them are unhealthy the person.

Exhaust gases, getting through a porous surface of a monolith, first, heat up it, and secondly, доокисляются. From WITH CO2 that is nontoxical carbon dioxide turns out, CnHm in some stages passes to CO2 and H2O, NOx turns into molecular N2 which contains in usual air, and in water. In a word, in converter there are quite difficult chemical reactions thanks to high temperature and existence of a special covering from expensive metals serving as catalysts.

So, the main positive effect of this adaptation – complete neutralization of three components – WITH, CnHm, NOx, – which in exhaust gases more than other harmful substances. Also it is reached not only thanks to availability of platinum, rhodium and a palladium. An important role plays, as I already told, the temperature which is maintaining in borders of 300-800 ° by S.Esli it decreases to 250 ° With, chemical reactions of neutralization WITH, CnHm, NOx, despite availability of metals catalysts, will not occur. And at temperature about 900 ° With the catalytic film starts to melt and collapse.


Not to put out of action serviceable converter, it is necessary to adhere to rules of its operation strictly. First of all, it is impossible to use etilirovanny gasoline. It is enough to spend 20–30 l of this gasoline, – and the active surface of the catalyst will become covered by lead that will lead to breakage.

It is necessary constantly and to watch closely for technical an engine condition. Converter does not maintain considerable deviations as a part of a fuel mix. At operation of the engine on rich and very rich mixes it is quickly hammered by a soot and other deposits, and on poor and very poor – overheats before fusion of an active layer. For maintenance of structure of a mix in necessary borders on cars with converters the oxygen sensor – a lambda probe is surely established, – on which signal the electronic control unit measures structure of a fuel mix. Serviceability and the correct work of system of regulation in many respects define durability of converter. Therefore at any failures in operation of the engine because of system of ignition or the complicated start-up – it is necessary to find and eliminate malfunction.

It is forbidden to start the engine from a tow, long to twist it a starter or it is frequent with short intervals to try to start not heated-up. Besides, not to allow emergence of cracks, it is necessary to avoid blows about road barriers. The reason of mechanical damage owing to sharp temperature difference can become car hit in a deep hollow with water and sharp cooling heated up to 800–900 ° From converter.

It should be noted that recently started to let out catalytic converters with a metal monolith that increases their durability. They it is much more reliable thanks to bigger stability to different mechanical and temperature influences but therefore they and are more expensive than ceramic analogs.

As already noted, converter with a ceramic monolith is very sensitive to blows therefore it it is impossible to drop or use a percussion instrument at work with system. And to avoid adjournment of fats, it is forbidden to touch by hands of a working surface of the sensor of oxygen. It is impossible to check spark existence by removal of a tip from any spark plug or to use supernumerary candles, and also to check overall performance of cylinders a method of shutdown of a spark a motortester. These actions can cause hit of not burned down fuel in the catalyst, about consequences of that is told above.

Pluses and minuses

The first and main plus of this adaptation – almost complete neutralization of the most harmful (considering their total concentration and toxicity) components of exhaust gases. The second plus consists that automakers without additional costs of improvement of serial engines, having established converter and control systems toplivopodachy with a lambda probe, can continue release of cars which, for example, Euros-2 and even Euro-3 completely answer rigid standards of toxicity of exhaust gases.

But is at converter and minuses. One of its essential shortcomings – low reliability, and not only because of fragility of a ceramic monolith, but also because of refusal owing to ekpluatatsiya violation of the rules, and even when these rules are not broken. According to inspections, quicker catalysts break in the conditions of city driving with frequent starts of the engine and short run. And also – at steady high-speed movement on highways. In the first case converter is simply hammered by fuel and a soot, after all at each start it should get warm to working temperature, and on it time is necessary. In the second – from overheating.

The rare car will long work for us with neutralization system, considering a road condition, security with unleaded gasoline and quality of this gasoline, no less than professional and ecological consciousness of drivers and repairmen. This darling but not "long-playing" system operates in the car before emergence of the first problems. And then, as a rule, the monolith is beaten out from the case and it simply throw out.

The logic of similar "measures" is clear: first, it is much cheaper, quicker and more simply, than to look for, agree and wait, while will bring new converter; secondly, these actions will not entail any negative consequences because practically all foreign cars with serviceable system of injection of gasoline keep within GOST operating nowadays (that for the car owner, unfortunately, will not tell about many Sngovsky cars).

So arrive at us and how at "them" where also norms on toxicity more rigid, and gazoanalitichesky control is adjusted, and money at the people is found, and are expensive as it should be, and service at height? There, if converter failed, it simply replace to avoid too high penalties for the increased toxicity. By the way, replace too not always reasonably because and at them not everyone HUNDRED has a complete set of the necessary equipment and the corresponding details. The discontent of consumers arising in this regard, increases demand for cars without converters. These are cars with gas, diesel and gazo-diesel engines, and also with direct injection of gasoline, and other Euros-3 keeping within norms without converters.