Valve timing of the M120.980 series engine
Check the digital designation of the camshafts. The codes are stamped on the neck of the 3rd bearing or on the flange.
Intake camshafts
1. Turn the crankshaft with a wrench so that the cam noses of the intake camshafts point upwards.
2. Install the retainer (2) dial gauge with threaded bushing (4) on the sealing surface of the cylinder head cover of the cylinder camshaft being checked (1) or (7).
3. Attach the dial gauge (1) with stem (3) (80 mm) on the latch (2) so that the stem (3) mounted vertically on the hydraulic compensator (arrow) with an interference of 3 mm.
4. Check the ease of movement of the stem (3).
5. Set the arrow dial gauge (1) V «0».
6. Turn the crankshaft with a wrench in the direction of engine rotation until the gauge (1) will not show valve lift of 2mm. In this position, check on the vibration damper «intake valve opening angle after TDC».
Exhaust camshafts
1. Turn the crankshaft with a wrench so that the noses of the cams of the exhaust camshafts point upwards.
2. Install the retainer (2) dial gauge with threaded bushing (4) on the sealing surface of the cylinder head cover of the cylinder camshaft being checked (1) or (7).
3. Attach the dial gauge (1) with stem (3) (80 mm) on the latch (2) so that the stem (3) mounted vertically on the hydraulic compensator (arrow) with an interference of 3 mm.
4. Check the ease of movement of the stem (3).
5. Set the meter needle (1) V «0».
6. Turn the crankshaft with a wrench in the direction of engine rotation until the meter shows 2 mm valve lift. In this position, check on the vibration damper «exhaust valve opening angle before BDC».