Piston Ring: Service and Repair

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.

Fig.7 Piston Dimensions:

Fig.8 Ring Side Clearance Measurement:

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

Groove Height

A 1.530 - 1.555 mm (0.0602 - 0.0612 inch)
B 4.035 - 4.060 mm (0.1589 - 0.1598 inch)

Top Compression Ring 0.042 to 0.084 mm (0.0017 to 0.0033 inch)
Second Compression Ring 0.042 to 0.084 mm (0.0017 to 0.0033 inch)
Oil Control Ring 0.06 to 0.21 mm (0.0024 to 0.0083 inch)

Fig.9 Gap Measurement:

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.

Top Compression Ring 0.229 to 0.610 mm (0.0090 to 0.0240 inch)
Second Compression Ring 0.483 to 0.965 mm (0.0190 to 0.0380 inch)
Oil Control Ring 0.254 to 1.500 mm (0.010 to 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.

Fig.10 Top Compression Ring Identification:

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.11 Second Compression Ring Identification:

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.13 Compression Ring Installation:

8. Using a ring installer, install the second compression ring with the dot facing up.
9. Using a ring installer, install the top compression ring.

Fig.14 Ring Gap Orientation:

- Position the gaps on the piston as shown.
- 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.