Note. To fix the engine in the TDC position, to reset the valve timing adjusters and to check the correct position of the camshafts, special devices are needed. 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 working cycle - at the end of the compression stroke and at the end of the exhaust stroke. Usually, the engine position is considered to be when the piston in cylinder #1 is at TDC at the end of the compression stroke. The 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, such as removing and installing the timing chain, camshafts, etc.
3. Remove the cylinder head cover (see paragraph 4).
4. Remove the plastic cover from the intake shaft (Fig. 3.4).
5. To correctly position the camshafts, install the valve timing adjusters as follows. Unscrew the oil feed pipe union from the intake shaft adjuster. Install the BMW 11 3 450 device (Fig. 3.5) onto the adjuster inlet.
6. Cover the regulator with a clean cloth.
7. Connect a compressed air source to the device and apply a pressure of 2 to 8 bar. This pressure will reset the regulators when the engine rotates.
8. Turn the engine crankshaft with a wrench by the head of the pulley bolt at least two full turns until the protrusions of the front cams of the intake and exhaust shafts are directed towards each other. In this case, the flat sides of the flanges on the rear ends of the camshafts should be perpendicular to the upper plane of the cylinder head. In this position, fix the camshafts with BMW 11 3 240 devices. If you cannot get the original devices, you can make them yourself from a steel or aluminum plate (fig. 3.8.a, b).
9. Remove the plug from the rear flange of the engine crankcase (access can be improved by removing the starter - see Chapter 5A).
10. To fix the crankshaft in the installation position, the BMW 11 2 300 device is required. If you do not have the original one, such a device can be turned from a steel rod (Fig. 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) (fig. 3.11,a,b).
12. Now the engine is set to the TDC position of piston No.1. Disconnect the compressed air from the regulators.
Caution! If for any reason it is now necessary to turn one or both camshafts, or remove the chain or loosen the tensioner, take note of the following precaution: Before turning the camshafts, turn the crankshaft approximately 30° counterclockwise (don't forget to remove the retainer from the flywheel before doing this), to prevent the possibility of pistons hitting the valves.
13. Do not attempt to turn the crankshaft. If the flywheel or camshaft is fixed with devices, the engine may be damaged. If it is necessary to leave the engine fixed for a long time, leave appropriate precautions in the car interior and in the engine compartment. This will reduce the likelihood of an attempt to start the engine with the starter.