Valve timing of the M120.980 series engine
Check the digital designation of the camshafts. The codes are stamped on the journal of the 3rd bearing or on the flange.
Intake camshafts
1. Turn the crankshaft with a wrench so that the camshaft lobes point upward.
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2. Install the dial gauge retainer (2) with the threaded sleeve (4) onto the sealing surface of the cylinder head cover of the camshaft being tested (1) or (7).
3. Attach the dial gauge (1) with the rod (3) (80 mm) to the clamp (2) so that the rod (3) is installed vertically on the hydraulic compensator (arrow) with an interference fit of 3 mm.
4. Check the ease of movement of the rod (3).
5. Set the dial gauge arrow (1) to "0".
6. Rotate the crankshaft with a wrench in the direction of engine rotation until the gauge (1) shows a valve lift of 2 mm. In this position, check the "intake valve opening angle after TDC" on the vibration damper.
Exhaust camshafts
1. Turn the crankshaft with a wrench so that the exhaust camshaft lobes point upward.
2. Install the dial gauge retainer (2) with the threaded sleeve (4) onto the sealing surface of the cylinder head cover of the camshaft being tested (1) or (7).
3. Attach the dial gauge (1) with the rod (3) (80 mm) to the clamp (2) so that the rod (3) is installed vertically on the hydraulic compensator (arrow) with an interference fit of 3 mm.
4. Check the ease of movement of the rod (3).
5. Set the meter pointer (1) to "0".
6. Rotate the crankshaft with a wrench in the direction of engine rotation until the gauge shows a valve lift of 2 mm. In this position, check the "exhaust valve opening angle before BDC" on the vibration damper.