Piston Ring Clearance Inspection

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Measure the piston ring-to-ring groove clearance around the entire circumference.
- If the piston ring-to-ring groove clearance exceeds the maximum clearance, replace the piston and piston ring.
Standard Clearance
1. Top: 0.040-0.075 mm {0.0016-0.0029 in}
2. Second: 0.040-0.085 mm {0.0016-0.0033 in}
Maximum Clearance
1. 0.10 mm {0.0039 in}
  
  Fig 1: Measuring Piston Ring-To-Ring Groove Clearance
  Courtesy of MAZDA MOTORS CORP.
Insert the piston ring into the cylinder by hand and use the piston to push it to the bottom of the ring travel.
Measure each piston ring end gap with a feeler gauge.
- If the piston ring end gap exceeds the maximum end gap, replace the piston ring.
Standard End Gap
1. Top: 0.10-0.25 mm {0.004-0.009 in}
2. Second: 0.27-0.42 mm {0.011-0.016 in}
3. Oil (Rail): 0.15-0.65 mm {0.006-0.025 in}
Maximum End Gap
1. Top: 0.50 mm {0.019 in}
2. Second: 0.65 mm {0.025 in}
Oil (Rail): 0.90 mm{0.035 in}

Fig 2: Measuring Each Piston Ring End Gap
Courtesy of MAZDA MOTORS CORP.