Remove the stiffening plate and drain the oil from the engine. Remove the lower part (pan) of the engine oil pan. Unscrew the M10x1.0 nut (25, see Fig. 5.15) and remove the sprocket (24) of the oil pump drive together with the drive chain (1).
Further work should be carried out with an assistant. Unscrew the bolts (M8) (22, 23, see Fig. 5.15) oil pump mounts and remove it. The bolts are not suitable for further use.
When installing, it is necessary to replace the sealing ring (1, Fig. 5.158) in the engine block crankcase, after lubricating it with engine oil.
Insert oil line (3, see Fig. 5.15) into the crankcase, avoiding damage to the sealing ring (2). When installing the oil pump, it is necessary to replace its sealing ring (4), having previously lubricated it with engine oil. Insert the oil line (3) into the hole in the oil pump, avoiding damage to the sealing ring.
Replace the sealing ring (2), after lubricating it with engine oil. Avoid damaging the sealing rings. Make sure the oil line is installed correctly.
New bolts (M8, class 10.9) tighten the oil pump mounts to a torque of 34 N·m (3.4 kgf·m). Tighten the nut (25, M10) securing the oil pump sprocket to a torque of 45 N·m (4.5 kgf·m). Assemble the engine.
(The original text is available on the website «BMWMan»)