Piston: Testing and Inspection

^ Tools Required:
- J 26900-3 Outside Micrometer
- J 8087 Cylinder Bore Gage
- Or Equivalent





1. Piston diameter using a Outside micrometer at the piston grading position located 15 mm (0.59 inch) from the piston skirt end and in the direction perpendicular to the piston pin. Record measurement.





2. Cylinder bore inside diameter using a cylinder bore gage. Cylinder bore diameter limit is 75.15 mm (2.9586 inch).





3. Piston oil clearance by subtracting the piston outside diameter from the cylinder bore inside diameter. If the piston oil clearance is not 0.02 to 0.04 mm (0.0008 to 0.0015 inch) in any cylinder, replace all four pistons. If necessary, rebore all three cylinders or replace the cylinder block.
^ There are three sizes of piston available; one standard and two oversize:
- Standard piston diameter specification: 74.970 to 74.990 mm (2.9516 to 2.9523 inch).
- 0.25 mm (0.0098 inch) oversized piston diameter specification: 75.220 to 75.230 mm (2.9614 to 2.9618 inch).
- 0.50 mm (0.0196 inch) oversized piston diameter specification: 75.470 to 75.480 mm (2.9712 to 2.9716 inch).
4. Piston ring groove clearance by fitting a new piston ring into the piston groove and measuring the clearance between the ring and ring land using an appropriate feeler gage. Before measurement can be made, the piston grooves must be clean, dry, and free of carbon.
^ Piston upper compression ring groove clearance specification: 0.03-0.07 mm (0.0012-0.0027 inch).
^ Piston lower compression ring groove clearance specification: 0.02-0.06 mm (0.0008-0.0023 inch).
^ If ring groove clearance is not within specification, the piston must be replaced.