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

WARNING: This page is about a different car, the 2011 BMW M3, 2010 BMW M3, 2009 BMW M3, and 2008 BMW M3. However, it is still accessible from the selected car via links, so may be relevant.

Necessary preliminary tasks:

Remove all PISTONS

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

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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

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

Piston ring (2), stepped ring.

Piston ring (3), plain compression ring.

Fig 3: Identifying Piston Rings

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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

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Measure AXIAL PLAY .

Fig 5: Measuring Piston Ring Axial Play

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Measure END CLEARANCE .

Fig 6: Measuring Piston Ring End Clearance

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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

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Assemble engine.