11 25 671 Replacing piston rings on all pistons (S65)

WARNING: This page is about a different variant/trim than selected.

Necessary preliminary tasks:

Remove piston rings with a 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.

Fig 1: Removing Piston Rings

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

Piston rings marked with "R" must point to piston crown.

Groove (2), plain compression ring.

Groove (3), stepped ring.

Groove (4), bevel-edged oil control ring.

Fig 2: Identifying Piston Ring Groove

Courtesy of BMW OF NORTH AMERICA, INC.

Piston ring (1), bevel-edged oil control ring.

Piston ring (2), stepped ring.

Piston ring (3), plain compression ring.

Fig 3: Identifying Piston Rings

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

Piston rings marked with "R" must point to piston crown.

Plain compression ring is marked with (R).

Stepped ring is marked with (R1).

Fig 4: Identifying Ring Marks

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 5: Measuring Piston Ring Axial Play

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 6: Measuring Piston Ring End Clearance

Courtesy of BMW OF NORTH AMERICA, INC.

Offset the contact points of the piston rings by approx. 120° to each other but do not position above the piston pin boss.

NOTE: See picture S85.

Fig 7: Identifying Piston Rings Contact Points

Courtesy of BMW OF NORTH AMERICA, INC.

Assemble engine.