BMW 3 Series E30

since 1983-1994 release

Repair and operation of the car

+ 1. Maintenance instruction
+ 2. Maintenance
- 3. Engine
   + 3.1.2. Specifications
   - 3.2. Dismantle and capital repairs of the engine
      3.2.2. Specifications
      3.2.3. Capital repairs – the general instructions
      3.2.4. Check of a compression in engine cylinders
      3.2.5. Capital repairs – general comments
      3.2.6. Diagnostics of the engine by means of the vacuum gage
      3.2.7. Capital repairs – alternatives
      3.2.8. Dismantle of the power unit
      3.2.9. Removal and installation of the engine
      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 valvate 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. Dismantle of the crankshaft
      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 conrod 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 conrod bearings
      3.2.30. Launch of the engine 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. Useful tips


3.2.5. Capital repairs – general comments


It is not always easy to come to a conclusion about expediency of complete capital repairs of the engine as it is necessary to be based on a number of objective indicators.

The big run is not a sufficient indicator of need of carrying out capital repairs, on the other hand, small run does not exclude need of carrying out capital repairs. The most important indicator most likely is timeliness of the current maintenance of the engine. At timely change of oil and the filter, and also when performing all other necessary works on service, engine serves reliably throughout many thousands of kilometers of a run. On the contrary, insufficient on volume or untimely maintenance can be the reason of sharp reduction of a resource of the engine.

The raised consumption of oil indicates wear of piston rings, directing plugs of valves and oil scraper caps. It is necessary to be convinced that leaks are not the reason of the raised oil consumption, and only after that to draw a conclusion about unfitness of piston rings and the directing plugs of valves. To define a probable cause of malfunction, measure a compression in engine cylinders.

For scoping of the forthcoming works check a compression in engine cylinders. Carry out also tests by means of the vacuum gage and define character of indications of this device. Check oil pressure the manometer screwed to the place of the sensor of pressure of oil and compare result of check to standard value. If oil pressure low, then can be the cause wear of radical and conrod bearings or details of the oil pump.

Loss of power, "failures" in operation of the engine, detonation or metal knocks, increased noise from the gas-distributing mechanism, increased fuel consumption indicate the need carrying out capital repairs, especially, if all these signs of abnormal work are shown at the same time. If performance of all adjustments does not lead to improvement, then the only means of elimination of abnormal operation of the engine are capital repairs. Capital repairs consist in restoration of details of the engine to the state specified in specifications for the new engine. When carrying out capital repairs pistons and piston rings are replaced, cylinders are chiseled or honningutsya. After repair of cylinders which is carried out in a specialized workshop installation of repair pistons will be required. Connecting and radical rods of the crankshaft, and also cover of basic necks of a cam-shaft are also subject to replacement, if necessary it is necessary to proshlifovat crankshaft necks before restoration of normal gaps with connecting and radical rods. As a rule, also valves as their state at the time of repair as a rule not absolutely satisfactory are subject to repair. During capital repairs of the engine repair of such units as a starter, generator and the distributor of ignition is also carried out. As a result the repaired engine has to have qualities of the new unit and sustain a considerable run without refusals.


At capital repairs it is necessary to replace such important details of the cooling system as hoses, drive belts, thermostat and the pump of cooling liquid. The radiator should be surveyed on tightness and purity of internal channels. If you bought the repair engine, or the block of cylinders of an incomplete complete set, then some suppliers do not give a guarantee for operation of these units without high-quality washing of a radiator. At capital repairs of the engine it is also recommended to replace the oil pump.

Before capital repairs of the engine study the description of the corresponding procedures that there was an impression of the forthcoming amount of works and requirements to them. At respect for all norms and rules, in the presence of all necessary tools and devices, it is simple to execute capital repairs, however considerable costs of time will be involved. Approximately not less than two weeks, especially are required if for repair and restoration of details it is necessary to address in a specialized workshop. Check existence of spare parts and in advance think of acquisition of necessary special tools and the equipment. Almost all works can be performed by means of standard tool kit though precision measuring instruments will be necessary for check and definition of suitability of these or those details. Often check of a condition of details is carried out in specialized workshops in which also receive recommendations about replacement or restoration of these or those details.


It is necessary to address in workshops of car service only after full dismantling of the engine and check of a condition of all details, especially the block of cylinders to solve what operations on service and repair will be carried out in workshops.

As the condition of the block of cylinders is the defining factor of making decision on its further repair or about purchase new (or repair) block of cylinders, it is necessary to buy spare parts or to carry out operations on machining of the accompanying details only after careful check of its technical condition. Make it a rule that the true price of repair is time, – then it is not necessary to pay for installation of the worn-out or restored details.

In conclusion we will note that assembly of any units should be carried out with all care in the pure room to avoid further failures of the repaired engine and to ensure its reliable functioning.