Note. For fixing the engine in the TDC position. special tools are needed to reinstall the valve timing regulators and to check the correct position of the camshafts. Making them yourself is not easy. Read the entire text before deciding on this operation.
1. Top dead center (TDC) is the top position of each piston as it moves up and down during engine operation. Each piston reaches TDC twice per cycle, at the end of the compression stroke and at the end of the exhaust stroke. Typically, the installation position of the engine is considered to be when the piston in cylinder No. 1 is at TDC at the end of the compression stroke. Cylinder numbering starts from the timing chain.
2. Setting the engine to the TDC position of piston No. 1 requires many disassembly, assembly and repair procedures, for example, removal and installation of the timing chain, camshafts, etc.
3. Remove the cylinder head cover (see paragraph 4).
4. Remove the plastic cover from the intake shaft (pic. 3.4).
5. For the correct location of the camshafts, it is necessary to install the valve timing adjusters as follows. Unscrew the oil supply pipe union from the intake shaft regulator. Fit BMW tool 11 3 450 to the regulator inlet (pic. 3.5).
6. Cover the regulator with a clean cloth.
7. Connect a compressed air source to the tool and apply pressure between 2 and 8 bar. This pressure will reset the regulators as the engine rotates.
8. Turn the engine crankshaft with a wrench on the head of the pulley bolt at least two full turns until the projections of the front cams of the intake and exhaust shafts are directed towards each other. In this case, the flat sides of the flanges at the rear ends of the camshafts must be perpendicular to the upper plane of the cylinder head. In this position, fix the camshafts with BMW tools 11 3 240. If you could not get branded tools, you can make them yourself from a steel or aluminum plate (pic. 3.8.a, b).
9. Remove the plug from the rear flange of the crankcase (access can be improved by removing the starter - see chapter 5A).
10. To fix the crankshaft in the installation position, a BMW 11 2 300 tool is required. In the absence of a branded tool, such a tool can be machined from a steel bar (pic. 3.10).
11. Insert the tool through the hole in the crankcase flange into the flywheel (to do this, you can turn the crankshaft a little) (pic. 3.11, a, b).
12. The engine is now at TDC #1 piston. Disconnect the compressed air from the regulators.
Attention! If now for some reason it is necessary to turn one or both camshafts, either remove the chain or loosen the tensioner. please note the following caution. Before turning the camshafts, rotate the crankshaft approximately 30°counterclockwise (Don't forget to remove the latch from the flywheel before doing this), to prevent the pistons from sticking into the valves.
13. Do not try to turn the crankshaft. if the flywheel or camshaft is fixed with fixtures, the engine can be damaged. If you want to leave the engine in a fixed state for a long time, leave the appropriate warnings in the passenger compartment and in the engine compartment. This will reduce the likelihood of the starter attempting to start the engine.