Piston Ring

WARNING: This page is about a different car, the 2003 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.

Check the piston ring for damage, excessive wear, and breakage. Replace if defects are evident. If the piston has been replaced, the piston rings must also be replaced.
Check for clearance between the piston ring and ring groove. If it exceeds the limit, replace the ring or piston, or both.
1. Standard value: 0.02 - 0.06 mm (0.0008 - 0.0023 inch
2. Limit: 0.1 mm (0.003 inch)
  
  Fig 1: Checking Clearance Between Piston Ring And Ring Groove
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Insert the piston ring into the cylinder bore. Force the ring down with a piston, the piston crown being in contact with the ring, to correctly position it at right angles to the cylinder wall. Then, measure the end gap with a feeler gauge. If the ring gap is excessive, replace the piston ring.
Standard value:
1. Number 1: 0.25 - 0.35 mm (0.009 - 0.013 inch)
2. Number 2: 0.40 - 0.55 mm (0.015 - 0.021 inch)
3. Oil: 0.10 - 0.40 mm (0.003 - 0.015 inch)
Limit:
1. Number 1, Number 2: 0.8 mm (0.03 inch)
2. Oil: 1.0 mm (0.03 inch)
  
  Fig 2: Checking Piston Ring End Gap
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.