Attention! On engines with oil piston cooling nozzles, be careful not to damage the nozzles when you remove the pistons. The manufacturer recommends that after removing and installing the pistons with connecting rods, adjust the position of the injectors using BMW tools 117 330 (engine M43TU) or 119 370 (N42 engine).
1. From a 4-cylinder engine, remove the cylinder head, sump and balance shaft housing as indicated in chapter 2A.
2. From a 6-cylinder engine, remove the cylinder head, sump and oil pump as indicated in chapter 2B.
3. Remove the oil damper (if he is) from the underside of the crankcase (pic. 9.3).
4. If there is a protruding belt on top of the cylinder bores, indicating cylinder wear, it is recommended to remove it with a reamer or scraper so as not to damage the pistons during disassembly.
5. Check if there are markings on the connecting rods and caps of the lower heads. Both the connecting rods and the caps of the lower heads must be numbered starting from the front end, i.e. from the camshaft drive circuit. If there is no such marking, apply it yourself with digital stamps or a center punch on the machined surfaces of the connecting rods and lower heads (pic. 9.5).
6. Rotate the crankshaft so that pistons #1 and #4 (4 cylinder engine) or 1 and 6 (6 cylinder engine) got to bottom dead center (NMT).
7. Turn out bolts of fastening of a cover of the bottom head of a rod N5 1. Remove a cover and take out from it the lower loose leaf (pic. 9.7). If the liners are not to be changed, tie the liner to the cap.
8. Use a hammer handle to push the piston up and out of the top of the cylinder. Remove the upper bushing from the connecting rod and tie it to the connecting rod. When performing this operation, be careful not to damage the oil nozzle in the cylinder.
9. Screw the lower head cover to the connecting rod to store them as a set.
10. In the same way, remove the piston with the connecting rod from the 4th (or from the 6th) cylinder.
11. Rotate the crankshaft so that the remaining pistons take turns at BDC, and remove the pistons with the connecting rods in the same way.