11 25 671 Replacing piston rings on all pistons (W10/W11)

Necessary Preliminary Tasks: 

• Remove pistons. Refer to 11 25 530 REMOVING AND INSTALLING/REPLACING ALL PISTONS (W10) .

Measuring axial clearance of piston rings in piston ring groove (1 and 2):

Refer to ENGINE - TECHNICAL DATA - COOPER (1.6L) R50/W10 .

Fig 1: Measuring Axial Clearance Of Piston Rings In Piston Ring Groove

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Remove piston rings (1 and 2) with piston ring compressing pliers.

Installation: 

Put aside piston rings in correct sequence and installation position.

New pistons may only be installed together with new piston rings.

Fig 2: Removing Piston Rings With Piston Ring Compressing Pliers

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Measure end clearance.

Refer to ENGINE - TECHNICAL DATA - COOPER (1.6L) R50/W10 .

Fig 3: Measuring Piston Ring End Clearance

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Installation: 

The taper face compression ring "top" is marked with an identification dot (1).

Fig 4: Identifying Marks On Compression Ring Taper Face

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Installation: 

Install piston rings with "identification dot" to piston crown.

1. Plain compression ring.
2. Taper face compression ring "identification dot".
3. 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.

Fig 5: Identifying Piston Rings Position

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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°.

Fig 6: Inserting Support Spring Into Piston Ring Groove

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