BMW 3 Series E30

since 1983-1994 release

Repair and operation of the car

+ 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. Useful tips
   14.2. The 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 trailer
   14.6. Preparation of the car for winter
   14.7. Rule 35
   14.8. Choice of the used car
   14.9. Engine oils
   14:10. What needs to be known, changing oil
   14:11. Emergence in deposit oil
   14:12. Whether it is possible to mix import oils?
   14:13. "Eats" much, but quietly goes
   14:14. It is rather live, than is dead …
   14:15. It is not got - useful tips
   14:16. Visit to car service
   14:17. A gear belt for the gas distribution mechanism drive
   14:18. Wear of pistons
   14:19. Valves
   14:20. Bearings of engines
   14:21. Pollution of the engine
   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. Antifreeze you should not disturb with antifreeze …
   14:26. What should be known upon purchase of the air filter
   14:27. Engine overheat
   14:28. What should be known to the owner of the car with the injector engine
   14:29. Accumulator
   14:30. Possible malfunctions of the rechargeable 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 the brake system
   14:37. Malfunctions of the brake system
   14:38. Brake fluids
   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. Galogenka
   14:52. About the correct adjustment of headlights
   14:53. Electric motor
   14:54. From change of the places "composed" nothing changes?


14:43. Metal corrosion


About of 70% of cost of the car are defined by a condition of a body. And it, in turn, depends on whether the car visited accident and, main thing, from extent of its corrosion damages.

The reasons causing the accelerated corrosion are subdivided into two groups and are connected:

– with design or technological features of concrete models;
– with external influences.

It is possible to carry to the first group:

– emergence of high tension and vibrations of metal of a body;
– existence of "pockets" in the bearing sections of bodies;
– use of a thin metal leaf (0,7–0,8 mm);
– use of metal with the impurity increasing corrosion speed;
– existence of concentrates of corrosion in the form of moldings and other jewelry.

Treat external influences:

– sulphurous connections, carbon dioxide and chlorides which are contained in the environment;
– salt solutions applied to fight against ice.

Under our conditions the greatest impact is made by various salt solutions as lead to formation of conducting "bridges" between body details, as a rule, having different electric potential. It causes the most swift-flowing type of destruction of metal – electrochemical corrosion. The point is that all cars have the single-wire electrical circuitry, and, therefore, on a body currents from one consumer to another "walk".

Let's not go deep further into the theory, having left it to experts in the field of corrosion, and we will address practical questions. These results are based on use during examination of three types of the devices allowing to estimate:

– change of thickness of "live" metal, that is not affected by corrosion;
– metal erosion degree from the inside, in other words, degree of its loosening or destruction by oxides;
– thickness of cosmetic layers (paint, filling) that allows to define whether there was a body under repair and attempts to hide it.

Results of expertizes which are carried out by experts allow to draw the following conclusions:

1. In the conditions of our region the speed of penetration of corrosion into metal for cars with winter operation makes – 0,2 mm a year and 0,1 mm a year for the cars which were not seeing salt.

2. Especially quickly corrosion in the zones which were exposed to body repair, and absolutely quickly develops if this repair was made with use of welding or the soldering as electrochemical couples from diverse metals are created. For buying the car, in particular the foreign car, it is essentially important. Not for nothing economical Europeans practically always sell even slightly beaten car (the truth, having received an insurance) for nothing – $1-2 of thousand. Then resell for how many them in our markets, reader, probably, knows also. But if you were lucky to find the latent defect before purchase commission, know that the actual cost of such car is of 25-50% lower, than at unbeaten. It is impossible to forget that sooner or later you will sell the car, and without experts expensive purchases are done now by only very naive people.

3. Most quickly there is a process of corrosion in the cars which are operated in the winter and stored in garages especially warm, without preliminary dissolution of salts flowing water. We emphasize, not washing off, namely dissolution. Very much those who believe that, washing away a strong stream the lower part of the car, they do a good deed are mistaken. Salts are easily dissolved also without strong pressure, and here sheetings from a powerful stream quickly enough "come unstuck" from metal, sag, creating only protection illusion. In the cavities which are formed between metal and the sagged mastic corrosion develops much quicker, than on open metal.


Extremely it is not recommended to wash the car with hot water as because of different temperature expansion the sheetings which are getting warm first of all "slip" from metal, forming negative effect.

Those who believe that the sheeting is thicker, better are not right. In total just the opposite. The main thing that in a covering there were no gaps, and therefore it needs to be updated regularly.

In conclusion – a practical advice. From two cars not that which is "younger", and on what process of destruction of metal did not get on depth more than 0,4-0,5 mm is better. In this case any processing it is impossible to prevent formation of holes in one and a half-two years. To the contrary, even the old car possessing since the beginning of operation reliable protection will serve a lot more years. Under our conditions in the foreign car it is possible to repair the engine and a running gear, but it is economically inexpedient to repair strongly rotted through body.