Piston To Cylinder Bore Clearance

Inner Diameter of Cylinder Bore

Using a bore gauge, measure cylinder bore for wear, out-of-round and taper at 6 different points on each cylinder. (X and Y directions at A, B and C). The Y axis is in the longitudinal direction of the engine.
NOTE: When determining cylinder bore grade, measure cylinder bore at B position. Refer to "STANDARD AND LIMIT ".
If the measured value rebore exceeds the limit, or if there are scratches and/or seizure on the cylinder inner wall, hone the inner wall.

Fig 1: Measuring Cylinder Bore For Wear, Out-Of-Round And Taper At Six Different Points
Courtesy of NISSAN MOTOR CO., U.S.A.

Outer Diameter of Piston

Measure piston skirt diameter using a micrometer. Refer to "STANDARD AND LIMIT ".

Fig 2: Measuring Piston Skirt Diameter Using Micrometer
Courtesy of NISSAN MOTOR CO., U.S.A.
Measure point (distance from the top): 42 mm (1.65 in)

Piston to Cylinder Bore Clearance

Calculate by outer diameter of piston skirt and inner diameter of cylinder (direction X, position B). (Clearance) = (Inner diameter of cylinder) - (Outer diameter of piston skirt).
Standard : 0.010 - 0.030 mm (0.0004 - 0.0012 in)

Limit : 0.08 mm (0.0031 in)
If it exceeds the limit, replace piston/piston pin assembly.

Reboring Cylinder Bore

Cylinder bore size is determined by adding piston-to-bore clearance to piston diameter "A".
Rebored size calculation: D = A + B - C

D: Bored diameter

A: Piston diameter as measured

B: Piston-to-bore clearance (standard value)

C: Honing allowance 0.02 mm (0.0008 in)
Install main bearing caps, and tighten to the specified torque. Otherwise, cylinder bores may be distorted in final assembly.
Cut cylinder bores.
- When any cylinder needs boring, all other cylinders must also be bored.
- Do not cut too much out of cylinder bore at a time.
Hone cylinders to obtain specified piston-to-bore clearance.
Measure finished cylinder bore for out-of-round and taper.
- Measurement should be done after cylinder bore cools down.