Lock the crankshaft in the TDC position with locating screw, BMW No. 11 6 570.
Insert chain through chain aperture and loop it around crankshaft.
Slide double drive gear (2) on to crankshaft.
Engage chain.
Install snap ring.
Clean threads of crankshaft and hexagon nut (1), coat threads with Loctite 243 and install nut.
Engage needle roller of water-pump drive gear on stub of compensating shaft and push drive gear (3) into position.
Tightening torque:
- Double drive gear on crankshaft (clean thread + Loctite 243): 180 Nm