Piston Ring: Service and Repair

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





Installation:
- Removing piston Service and Repair





Measure axial play.
Refer to Technical Data.





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.





Measure contact clearance with a feeler gauge.






Installation Note:
Install piston rings with "TOP" to piston top.

1. Twin-sided keystone
2. Oil scraper ring
3. Bevelled roof ring with rubber-lined spring
Arrange piston ring contact points with offset of approx. 120° to one another, but not over gudgeon pin eye.






Note:
Oil control ring comprises two steel band rings (1) and a support spring (2).

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





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





Assemble engine.