Piston Ring: Testing and Inspection

PISTON, PISTON RING, PISTON PIN INSPECTION




1. Measure the piston outer diameter using a micrometer. The measurement position is 12.5 mm {0.492 in} from the lower end of the piston, and in the thrust direction.

Piston outer diameter 77.970-77.980 mm {3.0697-3.0700 in}

2. Calculate the piston-to-cylinder clearance from the cylinder bore inner diameter and the piston outer diameter.
- If it exceeds the maximum specification, replace the piston or the cylinder block.

Clearance between piston and cylinder
Standard 0.020-0.043 mm {0.0008-0.0016 in}
Maximum 0.070 mm {0.0028 in}







3. Measure the piston ring-to-ring groove clearance around the entire circumference using a feeler gauge.
- If it exceeds the maximum specification, replace the piston ring.

Clearance between piston ring and ring groove
Standard
Top: 0.035-0.065 mm {0.0014-0.0025 in}
Second: 0.030-0.070 mm {0.0012-0.0027 in}
Oil: 0.040-0.120 mm {0.0016-0.0047 in}
Maximum
Top, Second: 0.150 mm {0.0059 in}
Oil: 0.20 mm {0.0079 in}




4. Measure the piston ring end gap using a feeler gauge.
- If if exceeds the maximum specification, replace the piston ring.

Piston ring end gap
Standard
Top: 0.14-0.24 mm {0.0056-0.0094 in}
Second: 0.24-0.37 mm {0.010-0.014 in}
Oil: 0.10-0.35 mm {0.004-0.013 in}
Maximum 1.0 mm {0.039 in}




5. Measure the piston pin hole diameter.
Measurement positions total eight and they are in the X and Y directions at four points (A, B, C, and D) as shown in the figure.

Standard piston pin hole diameter 18.988-19.000 mm {0.74756-0.74803 in}




6. Measure the piston pin outer diameter using a micrometer.
Measurement positions total eight and they are in the X and Y directions at the four points (A, B, C, and D) as shown in the figure.

Standard piston pin outer diameter 18.974-18.980 mm {0.74701-0.74724 in}

7. Calculate the clearance between the piston pin hole diameter and the piston pin outer diameter.
- If not within the specification, replace the piston or the piston pin.

Standard clearance between piston pin hole and piston pin 0.008-0.026 mm {0.0004-0.0010 in}