11 25 671 Replacing Piston Rings On All Pistons (N73)
WARNING: This page is about a different car, the 2008 BMW 760Li and 2007 BMW 760Li. However, it is still accessible from the selected car via links, so may be relevant.
Necessary preliminary tasks:
- Remove pistons. See 11 25 530 Removing and Installing/Replacing All Pistons (N73)
Measuring axial clearance of piston rings in piston ring groove (1 and 2):
See ENGINE - TECHNICAL DATA .
NOTE:
It is not possible to measure the axial clearance of the oil scraper rings.
Remove piston rings (1 und 2) with piston ring compressing pliers.
NOTE:
It might not be possible to find the identification on used piston rings.
Put aside piston rings in correct sequence and installation position.
New pistons may only be installed together with new piston rings.
Put aside piston rings in correct sequence and installation position.
New pistons may only be installed together with new piston rings.
Measure end clearance.
NOTE:
Picture shows a schematic representation.
Installation:
Install piston rings with "TOP" to piston top.
- Plain compression ring
- Stepped compression ring "Top"
- Two-part oil scraper ring.
Offset the contact points of the piston rings by approx. 120° to each other but do not position above the piston pin boss.
Installation:
Oil control ring comprises two steel band rings (1) and a support spring (2).
Insert support spring (2) into piston ring groove and then fit steel band rings (1) so that contact points are offset by approx. 120°.