Check of a condition of pistons / rods. BMW the 5th E28/E34 series (from 1981 to 1993 of release)
Repair of BMW E28 and series E34 from 1981 to 1993
1. Cars of the BMW brand of 5-series
2. Engine
2.1. The repair work which is carried out without extraction of the engine from the car
2.2. Procedures of major maintenance of components of the engine
2.2.1. General information
2.2.2. General information about major maintenance of the engine
2.2.3. Check of extent of compression
2.2.4. Ways of removal of the engine and precautionary measure
2.2.5. Removal and engine installation
2.2.6. Options of major maintenance of the engine
2.2.7. An order of dismantling of the engine at major maintenance
2.2.8. Dismantling of a head of cylinders
2.2.9. Cleaning and check of a condition of a head of cylinders and components
2.2.10. Service of valves
2.2.11. Assembly of a head of cylinders
2.2.12. Removal of pistons / rods
2.2.13. Removal of a cranked shaft
2.2.14. Removal and check of a condition of an intermediate shaft
2.2.15. Cleaning of the block of cylinders
2.2.16. Check of a condition of the block of cylinders
2.2.17. Honingovaniye of cylinders
2.2.18. Check of a condition of pistons / rods
2.2.19. Check of a condition of a cranked shaft
2.2.20. Check of a condition of radical and shatunny bearings
2.2.21. Engine balance of assembly at major maintenance
2.2.22. Installation of piston rings
2.2.23. Installation of an intermediate shaft
2.2.24. Installation of a cranked shaft and check of lubricant gaps of radical bearings
2.2.25. Installation of a back epiploon of a cranked shaft
2.2.26. Installation of pistons / rods in collecting and check of lubricant gaps in bearings of rods
2.2.27. Start and an engine running in after major maintenance
2.2.28. Diagnostics of malfunctions of the engine
3. Cooling system
4. Power supply system
5. Ignition system
6. Control systems of the engine and decrease in toxicity of the fulfilled gases
7. System of production of the fulfilled gases
8. Coupling
9. Manual box of gear shifting (RKPP) and automatic transmission (AT)
10. Transmission line
11. Steering and suspension bracket
12. Brake system
13. Body
14. Control body sizes
15. Heater and air conditioner
16. System of onboard electric equipment
17. Routine maintenance of the car
18. Size table and adjusting data
19. Schematic electric circuits
20. Governing bodies and operation receptions
21. System of onboard diagnostics - a principle of functioning and codes of malfunctions



2.2.18. Check of a condition of pistons / rods

Before check performance pistons/rods should be assembled cleared and old rings are removed from pistons.

When collecting the engine always apply new rings.


  1. Carefully, using the special adaptation, remove rings, pay attention to a mark (shooter) of top of a ring. Be careful not to leave on pistons of jags or dents.
  1. Remove from the piston bottom all traces of a deposit. After removal by a scraper of bulk of a deposit the manual wire brush or a piece of a small emery paper can be used. Under no circumstances do not use for deposit removal from pistons a wire brush in an electric drill. The piston is executed from a soft material and can be damaged by it.
  1. For deposit removal from flutes under rings use the adaptation for cleaning of flutes. Be very careful and delete only a deposit - do not delete metal and do not leave on lateral walls of flutes of a jag or scratch.

If the adaptation is inaccessible to cleaning of flutes, this work can be made a fragment of an old piston ring, however, protect hands - rings can be sharp.

  1. After removal of a deposit wash out pistons / rods solvent and dry up the compressed air (if it is available). Be convinced that maslovozvrashchayushchy openings in lateral surfaces of flutes under rings pure.
  2. If walls of cylinders and pistons are not damaged and have no excessive wear and if the block of cylinders was not exposed to polishing, new pistons be not required. Normal wear of the piston is shown in the form of uniform wear of persistent surfaces (at an angle 90 ° to an opening under a finger) and in the form of insignificant люфта in a flute of the top ring. However, at restoration of the engine it is necessary to establish new rings always.
  3. Attentively examine in search of cracks each piston round a skirt, on lugs of a finger and in flutes under rings.
  4. Examine persistent surfaces of a skirt in search of furrows and wear, the bottom - on existence of openings and bottom edge on existence of the scorched sites. If the skirt has furrows or istiraniye traces, that, probably, the engine was exposed to an overheat and / or abnormal extent of compression which causes emergence of the increased working temperatures takes place.
  5. It is necessary to check carefully system of cooling and greasing system. The opening in the bottom of the piston testifies that abnormal extent of compression (early ignition) took place. Obgoraniye traces on the brink of the bottom usually are a sign of explosive combustion (detonation). If there is any of these problems, it is necessary to eliminate the reason, differently malfunction happens again. Malfunction can represent leaks in the inlet pipeline, wrong fuel / an air mix or the wrong installation of ignition. On later models with the difficult control systems of release which are turning on catalytic converters, the problem can occur from EGR system (A retsirkulyatsiya of the fulfilled gases) if it is applied.
  6. The corrosion of the piston which is looking like small deepenings, testifies to penetration into the chamber of combustion and/or a cooler case, precisely also, it is necessary to eliminate the reason, differently the problem will arise again.
  1. Measure a lateral gap of a piston ring, having established in a flute a new piston ring and having inserted between it and a lateral surface of a flute, щуп.
  1. Check a gap in three or four places round each flute. Be convinced that check the corresponding ring - rings different. If more admissible, the piston it is necessary to replace a gap.
  1. Check a piston gap in the cylinder by subtraction of diameter of the piston from diameter of the cylinder. Be convinced that pistons and cylinders approach to each other. Measure diameter of the piston at skirt level along a finger and at an angle 90 ° to it.
  1. Any distinctions in these measurements testify to ovality existence. Subtract from diameter of the cylinder diameter of the piston and receive gap size. If a gap more admissible, the block it is necessary to grind and establish new pistons and rings.
  2. Check люфт between the piston and a rod, turning them in opposite directions. Any appreciable люфт testifies to excessive wear which it is necessary to eliminate. Assembled it is necessary to send a piston/rod for check in a workshop. After repair check rods on a bend and twisting as the majority of mechanical workshops have for this purpose the special equipment.

If installation of new pistons and / or rods is not made, do not separate pistons from rods.

  1. Check in rods existence of cracks and other damages. Temporarily remove covers of bearings of a rod, take old loose leaves, wipe surfaces of bearings in a rod and in a cover, and examine them on existence of jags, dents and scratches. After check of rods establish new loose leaves, put covers on a place and a hand tighten nuts.

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2.2.17. Honingovaniye of cylinders
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2.2.19. Check of a condition of a cranked shaft