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

3.2.29. Installation of rods and pistons, check of gaps in conrod bearings


Before installation of pistons assembled with rods the surface of the cylinder has to be absolutely pure, has to be chamfered edges of cylinders, and the crankshaft is installed in the block of cylinders.

1. Sort a rod of the 1st cylinder. Wipe a back surface of a new top connecting rod and lay it in the place in a rod. Make sure that the ledge on an insert came into selection in a rod and lubricant openings coincided. Not to grease an insert. Similarly establish the lower insert in a rod cover.
2. Place joints of piston rings so that they settled down at an angle 120 °.
3. Put on hoses bolts of rods. Oil pistons and rings pure for the engine, squeeze rings adaptation, having left the acting site of the piston to the 6-7th.
4. Turn the crankshaft to NMT in the first cylinder, oil cylinder walls for the engine.
5. Orient the piston so that dredging was turned towards a forward part of the engine.
6. Carefully enter the lower part of the piston with a rod into the first cylinder against the stop of adaptation in the block of cylinders. Slightly knock on the upper edge of a mandrel for uniform contact with the plane of the block of cylinders.

7. Enter the piston into the cylinder, carefully tapping with the wooden handle of the hammer on the piston bottom. Big effort not to apply. If resistance is felt, then immediately stop sideways and remove the cause of jamming.

8. Attract a rod to a neck of the crankshaft and check a gap in the conrod bearing.
9. The procedure of check differs in nothing from the procedure for radical bearings (see subsection 3.2.23). Rotation of the crankshaft or the slightest hit of oil on inserts at measurements are not allowed. Tighten nuts of a cover of a rod with the set moment (see subsection 3.2.2) a face head with thin walls (to exclude jamming of a head between a nut and a cover of a rod, on M10 and M20 engines tighten nuts in 3 stages). If the gap does not meet standard, then be convinced of lack of lubricant and dirt and again check diameter of a neck and correctness of selection of a connecting rod.

Final assembly of rods

1. Carefully remove the caliber remains, grease inserts and a conrod neck of the crankshaft, establish a cover and evenly tighten nuts with the set moment.
2. Repeat the procedure of measurement and assembly for other rods. Check freedom of rotation of the assembled crankshaft.
3. Check an axial side play of a rod (see subsection 3.2.15). Keep in mind that after installation of new rods the side play can be less norm and grinding of rods will be required.
4. Collect and install the engine.