Note. To fix the engine in the TDC position and to check the correct position of the camshafts, special tools are needed. Some of them you can do yourself (see text).
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. Usually, the position of the engine is considered to be the installation when the piston in cylinder No. 1 is at TDC 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. The operation of setting the engine to TDC is different depending on the engine model.
M43TU engine
4. Remove the cylinder head cover (see paragraph 4).
5. Rotate the crankshaft clockwise until the arrow on the crankshaft sprocket points straight up (pic. 3.5). The crankshaft can be turned with a socket or open-end wrench by the head of its central bolt.
6. Remove the plug from the left side of the rear motor flange.
7. To fix the crankshaft in the installation position, a special tool is required. You can use the proprietary fixture 11 2 300, but you can make it yourself (pic. 3.7).
8. Insert the rod through the hole in the engine flange into the hole in the flywheel. If necessary, turn the crankshaft slightly to the left and right (pic. 3.8).
9. The crankshaft is now fixed at TDC on piston #1.
10. When the engine shafts are properly installed, the sides of the square flange at the front end of the camshaft should be perpendicular to the top plane of the cylinder head (this can be checked with a square), and the holes in the flange should be on top.
11. For some operations, it is necessary to fix at TDC not only the crankshaft, but also the camshaft. To do this, you can make a device (sample), the dimensions of which are shown in Fig. 3.11, a. When the camshaft is correctly installed, the tool is put on top of the camshaft flange and keeps the shaft from turning (pic. 3.11.6). Also keep in mind that while piston #1 is at TDC, piston #4 is completing its exhaust stroke. This means that both valves in cylinder #4 are slightly open - the exhaust valve closes and the intake valve opens. The cams of cylinder No. 4 press on the rocker arms.
12. Do not try to turn the crankshaft if the flywheel or camshaft is fixed with tools - you can damage the engine. 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.
N42 engine
13. Remove the cylinder block cover (paragraph 4).
14. Rotate the crankshaft clockwise so that the beveled area on the crankshaft flange faces up (pic. 3.14). The crankshaft can be turned with a socket or open-end wrench by the head of its central bolt.
15. Remove the plug from the left side of the rear engine flange under the starter. Access to the flange is difficult. If necessary, remove the crankcase protection from under the engine. You can also remove the front amplifier (see paragraph 14). After that, you can get to the plug from below. Alternatively, remove the intake manifold (see chapter 4A) and free access to the flange from above (pic. 3.15).
16. To fix the crankshaft in the installation position, a special tool is required. You can use the proprietary fixture 119 190. but you can make it yourself (pic. 3.16) from a bar with a diameter of 8 mm and a length of approximately 80 mm. In order for the device to be pulled out of the flywheel, we drilled a hole at one end and screwed a second rod into it.
17. Insert the fixing rod through the hole in the engine flange into the hole in the flywheel. If necessary, turn the crankshaft slightly to the left and right (pic. 3.17). Note. In models with automatic transmission, there is a danger of making a mistake and inserting the rod into the large hole in the faceplate. Make sure that the crankshaft cannot be rotated with the rod inserted.
18. The crankshaft is now locked at TDC on piston #1.
19. Make sure that the camshafts are also in the installation position by trying to turn the camshafts towards each other. Use a square bar to turn the intake shaft, and an open end wrench to turn the exhaust shaft (on the shaft for the key there is a hexagon). If at least one shaft can be turned, keep turning it until it reaches the stop. If the camshafts cannot be turned, then the engine is locked in the installation position.
20. In this position, special brand tool 11 9 292 can be put on the front end of the intake camshaft, and special tool 11 9 291 can be put on the end of the exhaust shaft. If the shafts are correctly rotated, the tools should be easily inserted and reach the appropriate areas on the top side of the cylinder head cover. Fix the exhaust shaft fixing tool with screws, and tighten the intake shaft fixing screws (pic. 3.20, a, b). These devices fix the camshafts in such a way that the flat sides of their ends are installed perpendicular to the plane of the cylinder head.
21. Do not try to turn the crankshaft if the flywheel or camshaft is fixed with tools - you can damage the engine. If you want to leave the engine in a fixed state for a long time, leave the appropriate warnings in the cabin.