Note.
- On rings that have been in use, the marking may not be visible. Removed rings should be placed in the sequence of cylinder numbers and positions.
- Install new pistons only with new piston rings.
The piston rings must be replaced in the order given for the M54 engine, while the following must be taken into account.
The axial clearance of the compression rings should be 0.020–0.070 mm for the first ring and 0.020–0.060 mm for the second ring; measurements are not taken for the oil scraper ring.
The gap in the compression ring lock for all engines should be 0.10–0.30, and the oil scraper ring – 0.20–0.90 mm.
The oil scraper ring consists of two flat steel disks (1, Fig. 89) and one spring (2).
Insert the spring (2) into the ring groove and then install the steel discs (1). Move the ring locks apart at an angle of 120° relative to each other, while the ring joints should not be located above the piston pin bosses.
(The original text can be read on the website: «BMWMAN.ru»)