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?

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14.20. Bearings of engines


What bearings are established in your engine? Not all motorists answer such question intelligibly. One person far from equipment told directly: "Here ten years go, instead of I know that there is inside".

Nevertheless bearings there are. And not any, but quite certain. They are durable, but are not eternal, and when fail, without understanding of the main point not to manage. Well, and for professional repairmen it simply an ordinary matter.

As the bearing works

Sliding bearings almost only serve in modern automobile engines as support for cranked and camshafts. Kacheniye bearings (ball, roller, needle) apply to the similar purposes only in small motorcycle motors.

Necessary operability of bearings of sliding is reached by use of so-called effect of an oil wedge. At rotation of a smooth shaft in a gap between shaft and an opening oil moves. As the loading operating on a shaft, causes its excentric shift, oil is as though tightened in a being narrowed part of a gap and forms the oil wedge interfering contact of a shaft with walls of an opening. The more pressure and viscosity of oil in a gap, the big loading (before contact of surfaces) maintains the sliding bearing.

The actual pressure of oil in a zone of a wedge reaches 50–80 MPas (500–800 kg/cm2), and in some designs and it is more. It in hundreds times is higher, than in submitting system. However it is not necessary to think that pressure of giving influences operation of the bearing a little. The it is more, the there is an oil pumping via the bearing and the better it cooling more intensively.

Under certain conditions the operating mode with the minimum friction (it also call liquid) can be broken. It happens at ponizheniy to viscosity of oil (for example, because of its overheat owing to insufficient giving) and decrease in frequency of rotation at loading increase.

Quite often, especially after engine repair, not optimum geometry of knot affects also. At an insignificant deviation of a form of surfaces from cylindrical, at a distortion of axes and other defects of details probably local increase of specific loading (that is the loading carried to the area of a surface) above an admissible limit. Then the oil film in these parts becomes thin, and surfaces of a shaft and the bearing start to adjoin on microroughnesses. There is a mode of the semi-liquid greasing, being characterized increase of a friction and a gradual warming up of the bearing. Further it can lead to a so-called boundary friction with complete contact of the surfaces the overheat, skhvatyvany (teases), jamming, fusion and bearing destruction will be which consequence.

It is clear that in operation the mode of a boundary friction is unacceptable. Nevertheless it appears at violation of supply of oil, and it occurs because of its shortage in a case, that is or owing to oversight of the driver, or at damage of the pallet of a case as a result of arrival on an obstacle more often.

The mode of semi-liquid greasing is admissible only for short time when he does not manage to affect wear of the bearing. An example – start-up of the cold engine. However, there is other danger: at very low temperature oil можеты to be too viscous and its normal giving is restored long (20–30 seconds and more). Here already semi-liquid greasing is capable to affect wear of details considerably.

Improvement of automobile engines is connected with continuous growth of frequency of rotation and increase in capacity. Increase of compactness of designs, including reduction of width and diameter of bearings is at the same time observed. It means that specific tension grows in knot. And as load of the bearing at operation of the engine cyclically changes on size and the direction, there is real a so-called fatigue failure of details. To provide operability of bearings in such conditions, special designs, materials and technologies are required.

As it is arranged

Usually bearings of cranked shaft in modern engines carry out in the form of thin-walled loose leaves or plugs in thickness of 1,0-2,5 mm (it is rare more). Loose leaves of radical bearings of a cranked shaft do to thickness because of need to place a circular flute for supply of oil to shatunny bearings. The general tendency – reduction of thickness of loose leaves which now averages 1,8-2,0 mm at radical and 1,4–1,5 mm at shatunny bearings. The loose leaves are thinner, the better they adjoin to a surface of the case (bed), that the heat-conducting path from the bearing is better, the geometry, less admissible gap and noise at work is more exact, it is more knot resource.

That at installation in a bed the loose leaf precisely accepted its form, in a free condition it should have a tightness on diameter of a bed (so-called straightening) and not cylindrical form of variable radius. Besides, the tightness is necessary for a good prileganiye to a surface and deduction from a provorachivaniye and on length of the loose leaf – it call a vystupaniye. All these parameters depend on thickness, width and diameter of loose leaves, thus straightening averages 0,5–1,0 mm, and a vystupaniye – 0,04–0,08 mm. However for reliable operation of the bearing and it still it is not enough. About the socket thickness of loose leaves reduce by 0,010–0,015 mm to avoid задиров in these parts. They can appear because of opening deformation in the case under the influence of working loading when the working gap in the bearing is small.

Materials for loose leaves can be different. Their choice coordinates with a material of a cranked shaft and its heat treatment, degree of a forsirovka of the engine and the set resource. To a certain extent affect here and traditions of automobile firm.

Loose leaves always do multilayered. A loose leaf basis – a steel tape which provides durability and reliability of landing in the case. On a basis with various ways put a layer (or layers) a special antifrictional material in thickness of 0,3-0,5 mm. The main requirements to an antifrictional material – a low friction on a shaft, high durability and heat conductivity (that is heat from a surface is good to carry out to the bearing case ability). The first requirement soft metals, for example, best of all provide alloys with the big content of tin and lead (in particular, widely known babbits).

In the past babbits were widely applied on the low-forced low-turnaround engines. With growth of loadings durability of such loose leaves with a thick layer of babbit appeared insufficient. The problem was solved by replacement of all this layer by a peculiar sandwich – the svintsovoolovyanisty bronze covered thin (0,03–0,05 mm) a layer of the same babbit. The loose leaf became multilayered. In modern engines "stalebronzobabbitovy" loose leaves usually carry out 4-layer (under babbit very thin intermediate layer of nickel still lies) and even 5-layer when for improvement extra earnings from above the thinnest layer of tin is put on a working surface. Exactly bearings on many foreign engines so look.

Along with it the wide circulation was received also by steel-aluminum loose leaves. As an antifrictional material aluminum alloys with tin, lead, silicon, zinc or cadmium, both with coverings, and without them here serve. Most often in world practice the aluminum alloy from 20 % of tin without a covering is used. It well resists to high loadings and speeds of rotation of modern engines, including diesel engines, and at the same time possesses satisfactory "softness". Nevertheless steel-aluminum loose leaves are more rigid, than babbitovy (or with a babbitovy covering) therefore are more inclined to teases in the conditions of insufficient greasing.

Auxiliary and camshafts of engines rotate, as a rule, with smaller frequency, than cranked and test much smaller loadings therefore it is easier than a condition of their work. Loose leaves and plugs of these shaft usually do of the materials, similar by the aforesaid. Besides, here sometimes apply babbit or bronze without a covering. Often these bearings at all have no plugs or loose leaves and are formed directly rastachivaniy openings in a head of the block of cylinders. In such designs the head is executed from an aluminum alloy with silicon which possesses quite good antifrictional properties.

The general for bearings of modern engines, especially if it is a question of support of cranked shaft, compliance of a material and a design of loose leaves to a material and operating conditions of a shaft (frequency of rotation, loading, a greasing condition etc.) is. Therefore any replacement of details when, for example, at repair put loose leaves from other engine, cannot be recommended. Otherwise the durability of the repaired unit can appear very small. To decide on such step, it is necessary to have the relevant information.

Loose leaves are very exact (precision) details. To guarantee small (but quite concrete – on the average 0,03–0,06 mm) working gaps in bearings, when manufacturing maintain thickness of the loose leaf with accuracy about 5-8 microns, and length – 10–20 microns. Violation of these requirements can lead to change of a working gap in the bearing or density of landing of the loose leaf in the case that is inadmissible because of decrease in reliability and a resource of all engine as a whole.

Who makes them

Complexity of all circle of the problems connected with creation of high-quality automobile bearings of sliding, led to that their production gradually passed to specialized firms. Abroad many their such firms at the same time let out also other details of engines, and deliveries go both on conveyors of automobile works, and in spare parts. Some firms such are a part of known multinational production and commercial and industrial corporations. From world manufacturers of bearings for engines it should be noted firms Kolbenschmidt (KS), Glyco, TRW, Sealed Power, Glacier, Clevite, Bimet first of all. In recent years bearings started to do and such firms – "coryphaeuses", as Mahle and Goetze. Among "young" it is necessary to mention the specialized firm King (Israel) which has begun release of bearings in the early eighties.

The majority of the listed producers issues the huge nomenclature of bearings and delivers the production in the spare part everywhere, including on our market (through dealers or the wholesale trading companies). Generally certainly, it is bearings for foreign engines – European, Japanese and American.

It is possible to find loose leaves in sale both standard, and the various repair sizes (as a rule, no more than 0,75 mm) on the majority of the widespread Audi Volkswagen models, BMW, "Mercedes", "Ford", "Opel", "Fiat", "Toyota", "Nissan", "Mitsubishi", "Mazda" etc. On less widespread models, and also in need of purchase of loose leaves of the bigger repair size usually it is necessary to make out the order and to wait on the average for 5-10 days (at different trading companies these terms are various).

Quality of such production usually does not cause doubts neither on geometry, nor on materials. Though, if there is a choice and doubts in what firm manufacturer to prefer, it is necessary to mean the following. Such firms as, for example, Kolbenschmidt, Glyco, Glacier are one of main suppliers of mass production. Upon purchase of their products it is possible even to receive the same loose leaves that stood on the engine "since the birth". The difference will be only in absence on new details of an emblem of firm manufacturer of the car. By the way, search "native" (or so-called original) loose leaves of the repair sizes can appear problematic. Not all automobile firms deliver repair loose leaves in the spare part and the price of loose leaves in "original" packing is, as a rule, much higher, than directly from their producer.

Loose leaves of other, less eminent firms are usually cheaper, though on quality to find differences difficultly. Moreover, if there is a choice, here it is possible to try to consider and car service conditions. So, rather cheap loose leaves, strangely enough, resist to bad quality oils and маслофильтрам, "walking" on our shops and the markets, than more expensive stalebronzobabbitovy slightly better. It practice of use under repair steel-aluminum loose leaves of King firm instead of the regular bronzobabbitovy, in particular, showed – such replacement does not put a damage of reliability of engines, but allows to save considerably.

Some of the listed firms issue loose leaves and for our cars. In our market it is already possible to find these products for engines VAZ of production of Clevite, Bimet and Glacier firms. Certainly, they it is notable more expensively than the domestic. However to save on loose leaves at repair of domestic motors it is not necessary. Comparison with import production domestic usually does not maintain. Deviations on thickness at our some commodity copies reach 25–30 microns instead of 8 microns regulated by the admission. As a result after a zazhatiya a cover внутрення the surface of the bearing gets the wrong form at which, for example, the gap in 0,07–0,09 mm in one section of the bearing can even pass to a tightness in other.