Piston Ring: Service and Repair

STANDARD PROCEDURE - PISTON RING FITTING
1. Carefully clean the carbon from all ring grooves. Oil drain openings in the oil ring groove and pin boss must be clear. DO NOT remove metal from the grooves or lands. This will change ring-to-groove clearances and will damage the ring-to-land seating.
2. Be sure the piston ring grooves are free of nicks and burrs.








3. Measure the ring side clearance with a feeler gauge fitted snugly between the ring land and ring (Fig. 64) (Fig. 65). Rotate the ring in the groove. It must move freely around circumference of the groove.





RING SIDE CLEARANCE CHART
Top Compression Ring 0.042 - 0.084 mm 0.0017 - 0.0033 inch
Second Compression Ring 0.042 - 0.084 mm 0.0017 - 0.0033 inch
Oil Control Ring 0.06 - 0.21 mm 0.0024 - 0.0083 inch





4. Place ring in the cylinder bore and push down with inverted piston to position near lower end of the ring travel. Measure ring gap with a feeler gauge fitting snugly between ring ends (Fig. 66).





RING GAP MEASUREMENT CHART
Top Compression Ring 0.229 - 0.610 mm 0.0090 - 0.0240 inch
Second Compression Ring 0.483 - 0.965 mm 0.0190 - 0.080 inch
Oil Control Ring 0.254 - 1.500 mm 0.010 - 0.060 inch

5. The oil control rings are symmetrical, and can be installed with either side up. It is not necessary to use a tool to install the upper and lower rails. Insert oil rail spacer first, then side rails.





6. The two compression rings are different and cannot be interchanged. The top compression ring can be identified by the shiny coating on the outer sealing surface and can be installed with either side up. (Fig. 67).








7. The second compression ring has a slight chamfer on the bottom of the inside edge and a dot on the top for correct installation (Fig. 68) (Fig. 69).





8. Using a ring installer, install the second compression ring with the dot facing up (Fig. 68) (Fig. 70).
9. Using a ring installer, install the top compression ring (either side up).

Ring Gap Orientation





- Position the gaps on the piston as shown (Fig. 71).
- Oil spacer - Gap on center line of piston skirt.
- Oil rails - gap 180° apart on centerline of piston pin bore.
- No. 2 Compression ring - Gap 180° from top oil rail gap.
- No. 1 Compression ring - Gap 180° from No. 2 compression ring gap.