11 25 671 Replacing piston rings on all pistons (N47 D20 O1)

Necessary preliminary work:

Remove all piston rings (2) with piston ring pliers (1).

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 Using Piston Ring Pliers

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Installation note:

Piston rings with "TOP" identification must point to piston crown.

Arrange piston ring contact points with offset of approx. 120° to one another, but not over gudgeon pin boss.

Fig 2: Identifying Piston Ring Installation Position

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Installation note:

Marking (TOP) must point towards piston crown.

The oil scraper ring has no identification marking and can be installed in any position.

Fig 3: Identifying Piston Ring Mark

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Adjust piston rings to 120 degree position.

Fig 4: Identifying Piston Ring Positions

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Measure axial play.

Fig 5: Measuring Piston Rings Side Clearance

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Measure end clearance.

Fig 6: Checking Piston Ring End Clearance Using Feeler Gauge

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Assemble engine.