Piston Ring: Service and Repair

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

Remove Pistons






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




Technical Data:

Note: It is not possible to measure the axial clearance of the oil scraper rings

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

Note: It might not be possible to find the identification on used piston rings.





Installation: Put aside piston rings in correct sequence and installation position.

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





Measure end clearance.




Technical Data:





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





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.





Installation: Oil 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°.