11 25 671 Replacing piston rings on all pistons (M57T2-SCR)

Installation note:

Measure axial play.

Fig 1: Measuring Axial Play

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Remove piston rings with piston ring 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 2: Removing Piston Rings Using Piston Ring Pliers

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Measure end clearance with a feeler gauge.

Fig 3: Measuring End Clearance Using Feeler Gauge

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Installation note:

Install piston rings with "TOP" to piston crown.

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

Fig 4: Identifying Piston Ring Tops

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NOTE: Oil scraper ring comprises two steel band rings (1) and a bearing spring (2).

Installation note:

Insert bearing spring (2) into piston ring groove and then fit steel band rings (1) so that contact points are offset by approx. 120°.

Fig 5: Identifying Support Spring And Steel Band Rings

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Offset the contact points (1) of the piston rings by approx. 120° to each other but do not position above the gudgeon pin boss.

Illustration shows N52

Fig 6: Identifying Contact Point Of Piston Ring

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Assemble engine.