M112
Checking the basic position of the balancing shaft of the M112 engine
1 - Grooves in camshafts; 2 - Right camshaft locking plate; 3 - Hole in the rear counterweight; 4 - Rear counterweight; A - Pin in the crankcase; B - Risk on the front counterweight
1. Remove the transmission assembly (see Chapter Automatic transmission).
2. Remove the drive disk.
3. Check the basic position of the camshafts (see Section Checking and adjusting the basic position of the camshafts).
Note: On models equipped with an air pump, it is also necessary to remove the right combination valve, the sealing gasket of which must be replaced without fail.
4. Install the locking plates (2) on the right and left cylinder heads, inserting them into the grooves (1) of the camshafts.
5. When the balance shaft is correctly installed, the hole (3) in the rear counterweight (4) should align with the socket in the engine crankcase - insert a pin with a diameter of 8.40÷8.55 mm into the holes. Also make sure that the mark (B) on the front counterweight aligns with the pin (A) in the crankcase - the mark and pin are located approximately 22 cm below the mating surface of the head and are visible through the window in the left timing cover.
6. If the basic setting is not correct, the balance shaft must be replaced.
7. Reinstall all removed components in the reverse order of removal.
M628
Checking the basic position of the balance shaft of the M628 engine (1 of 2)
1 - Intake camshaft gear; 2 - Exhaust camshaft gear; 3 - Lid; 3a - Bottom bolt; 3b - Upper bolt; 5 - Spring; 7 - Balance shaft sprocket; 9 - Installation marks
Checking the basic position of the balance shaft of the M628 engine (2 of 2)
5 - Spring
6 — Marking
7 — Balance shaft sprocket
1. Remove the cylinder head covers (see illustrations Installation details of cylinder head covers for the M682 engine (1 of 2) and Installation details of cylinder head covers for the M682 engine (2 of 2)).
2. Remove the intercooler (Intercooler) turbocharging systems (see Chapter Fuel and exhaust systems).
3. Unscrew the lower bolt (3a) of the cover (3), - in order to provide access to the bolt, turn the crankshaft in the normal direction.
4. Bring the piston of the first cylinder to the TDC position.
5. Unscrew the upper bolt (3b) and remove the cover (3).
6. Remove the centrifuge.
7. Make sure that the tensioner (9) provides the required tension force of the timing chain.
8. Install the cover (3) on the crankcase and secure it with the upper bolt (3b).
9. Turn the crankshaft two full turns in the normal direction, again bringing the piston of the first cylinder to the TDC position.
10. Remove the cover (3) again.
11. Make sure that the basic installation of the camshafts is correct (see Section Checking and adjusting the basic position of the camshafts).
12. Check the correct basic installation of the balance shaft, the spring (5) of which should occupy the position shown in the picture, and the marking (6) on the sprocket (7) should be slightly offset from the "12 o'clock" position.
13. Proceeding in the reverse order of dismantling, install the removed components back into place.
14. Finally, read the DTC codes and clear the on-board diagnostic system memory using the STAR DIAGNOSIS scanner (6511 1801 00) (See Chapter Engine electrical systems).
Publication taken from an online resource Mercedesman.ru