E30 series BMW 3

since 1983-1994 of release

Repair and car operation

+ 1. Maintenance instruction
+ 2. Maintenance
- 3. Engine
   + 3.1.2. Specifications
   - 3.2. Dismantle and major maintenance of the engine
      3.2.2. Specifications
      3.2.3. Major maintenance – the general instructions
      3.2.4. Compression check in engine cylinders
      3.2.5. Major maintenance – general comments
      3.2.6. Engine diagnostics by means of the vacuum gage
      3.2.7. Major maintenance – alternatives
      3.2.8. Dismantle of the power unit
      3.2.9. Removal and engine installation
      3.2.10. Order of dismantling of the engine
      3.2.11. Dismantling of a head of the block of cylinders
      3.2.12. Cleaning and check of a head of cylinders and details of the klapanny mechanism
      3.2.13. Repair of valves
      3.2.14. Assembly of a head of the block of cylinders
      3.2.15. Removal of pistons and rods
      3.2.16. Crankshaft dismantle
      3.2.17. Intermediate shaft (only M20 engine)
      3.2.18. Cleaning of the block of cylinders
      3.2.19. Check of a condition of the block of cylinders
      3.2.20. Honningovaniye of cylinders
      3.2.21. Check of a condition of pistons and rods
      3.2.22. Check of a condition of the crankshaft
      3.2.23. Check of radical and shatunny bearings
      3.2.24. Engine assembly order
      3.2.25. Installation of piston rings
      3.2.26. Installation of an intermediate shaft
      3.2.27. Installation of the crankshaft and check of gaps in radical bearings
      3.2.28. Installation of a back epiploon
      3.2.29. Installation of rods and pistons, check of gaps in shatunny bearings
      3.2.30. Engine start-up after repair and a running in
   + 3.3. Engine electric equipment
+ 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


3.2.23. Check of radical and shatunny bearings


Types of wear of radical and shatunny bearings

A. Scratches because of dirt hit
B. Insufficient greasing
Page. Wrong installation of bearings
D. Wear because of a neck konusnost
E.Obrazovaniye of a facet on a bearing edge
F. Fatigue wear

Radical and shatunny bearings at major maintenance of the engine are subject to the obligatory replacement, however the bearings which were in operation should be checked carefully to restore the general condition of the engine at the moment of repair.

Causes of destruction of bearings of a cranked shaft are insufficient greasing because of the wrong assembly, pollution and penetration of extraneous particles, frequent overloads of the engine, corrosion, etc. Irrespective of the reason which has caused destruction of bearings, it is necessary to eliminate it.

At check of a condition of bearings they should be got from the block of cylinders, covers of radical bearings of a cranked shaft, shatunny covers and rods. Lay out loose leaves on a pure surface in the same order in which they were established on the engine.

Dirt and extraneous particles get to the engine for various reasons – in the course of assembly, via filters or system of ventilation of a case. Pollution can get also to oil, and from it – in bearings. Often at pollution there are metal particles from machining of details of the engine, or owing to wear at normal operation of the engine. Sometimes at pollution there are remains of abrasive materials after carrying out pritirochny and grinding works, especially at insufficient washing and engine pro-cleaning after their termination. Irrespective of the origin reason extraneous pollution usually take root into a soft alloy of the bearing and are easily distinguishable. Large particles cannot take root into the bearing and lead to emergence of scratches and задиров on surfaces as bearing and crankshaft necks.

Insufficient greasing of the engine ("oil starvation") can be caused by a number of the interconnected reasons. Overloads concern them (cause expression of oil from a surface of bearings) and pressure decrease because of leakage (emission) of oil (because of the raised gaps in bearings, wear of the oil pump, big frequency of rotation of a cranked shaft) an engine overheat (causes razzhizheny oils).

The durability of bearings of a cranked shaft also essentially depends on skills of driving. Bearings test the raised loadings at movement with completely open butterfly valve, or with small speed on an overgear (in heavy the engine modes). At the raised loadings there is an expression of an oil film. Bearings test flexural deformations at which microcracks (fatigue wear) are formed. As a rule there is a separation of a covering of the bearing from a steel basis in the form of small particles. Trips on small distances can be at the bottom of corrosion wear of bearings as because of insufficient warming up skondensirovanny moisture and the gases causing corrosion do not manage to be removed.

The wrong installation of bearings at assembly also results in their premature wear. If the gap in bearings is less than norm, their greasing is complicated that results in wear as well as owing to "oil to starvation". Dirt or the small particles which have got under the loose leaf of the bearing, lead to a local raising of the loose leaf and to the strengthened wear in this part.