Piston Ring
WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.
- Make sure the piston ring is not broken or damaged.
- Using a cylindrical guide, insert the piston ring into the cylinder liner so that they are perpendicular to the cylinder wall, and check the piston ring gap using a thickness gauge. If it is not within the standard, replace the piston ring.NOTE:
- Measurement should be performed at a temperature of 20°C (68°F).
- Use piston ring with same size as piston when replacing piston ring.
Piston ring gap:
Compression ring (top ring)
Standard
0.22 - 0.27 mm (0.0087 - 0.0106 in)
Compression ring (second ring)
Standard
0.35 - 0.45 mm (0.0138 - 0.0177 in)
Oil ring (upper rail and lower rail)
Standard
0.10 - 0.35 mm (0.0039 - 0.0138 in)
- Fit the compression ring straight into the piston ring groove, then check the clearance between compression ring and piston with a thickness gauge. If it is not within the standard, replace the compression ring.NOTE:
- Measurement should be performed at a temperature of 20°C (68°F).
- Before inspecting the clearance, clean the piston ring groove and compression ring.
- Use compression ring with same size as piston when replacing compression ring.
Clearance between compression ring and piston:
Top ring
Standard
0.040 - 0.080 mm (0.0016 - 0.0031 in)
Second ring
Standard
0.045 - 0.085 mm (0.0018 - 0.0034 in)