Piston Ring: Service and Repair

11 25 671 - Replacing piston rings on all pistons (N62)

(piston removed)





Measuring axial clearance of piston rings in piston ring groove (1 and 2):
Technical Data Pistons with Rings and Pins N62.

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





Remove piston rings (1 und 2) with piston ring compressing 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.
New pistons may only be installed together with new piston rings.





Measure end clearance Pistons with Rings and Pins N62.





Note:
Picture shows a schematic representation.

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

1. Plain compression ring
2. Stepped compression ring "Top"
3. Steel band ring with support spring
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 control ring comprises two steel band rings (1) and a support spring (2).
Insert support spring (2) into piston ring groove.

Caution!
Incorrect installation possible.
Contact points of support spring (2) slip very easily over each other when fitted.
Contact points must be positioned exactly on each other.
If the contact points overlap, the oil scraper ring will be damaged when the piston is installed.

Then fit steel band rings (1) so that contact joints are offset approx. 120°.