Piston To Cylinder Bore Clearance

Cylinder Bore Inner Diameter

• Using bore gauge, measure cylinder bore for wear, out-of-round and taper at six different points on each cylinder. ("X" and "Y" directions at "A", "B" and "C") ("X" is in longitudinal direction of engine)

  Standard inner diameter: 

  95.500 - 95.530 mm (3.7598 - 3.7610 in) 

  Out-of-round (Difference between "X" and "Y"): 

  0.015 mm (0.0006 in) 

  Taper limit (Difference between "A" and "C"): 

  0.01 mm (0.0004 in) 

  Fig 1: Identifying Piston To Cylinder Bore Clearance

  Courtesy of NISSAN NORTH AMERICA, INC.
• If the measured value exceeds the limit, or if there are scratches and/or seizure on the cylinder inner wall, hone or re-bore the inner wall.
  Fig 2: Measuring Clearance Of Piston-To-Cylinder Bore

  Courtesy of NISSAN NORTH AMERICA, INC.

Piston Skirt Diameter

Measure the outer diameter of piston skirt with micrometer.

Measure point 

: Distance from the top 43.03 mm (1.6941 in) 

Standard 

: 95.480 - 95.510 mm (3.7590 - 3.7602 in) 

Fig 3: Measuring Outer Diameter Of Piston Skirt Using Micrometer

Courtesy of NISSAN NORTH AMERICA, INC.

Piston to Cylinder Bore Clearance

Calculate by piston skirt diameter and cylinder bore inner diameter (direction "X", position "B"). (Clearance) = (Cylinder bore inner diameter) - (Piston skirt diameter).

Standard: 0.010 - 0.030 mm (0.0004 - 0.0012 in) 

Limit: 0.08 mm (0.0031 in) 

• If the calculated value exceeds the limit, replace piston and piston pin assembly. Refer to "HOW TO SELECT PISTON AND BEARING ".

Re-boring Cylinder Bore

1. Cylinder bore size is determined by adding piston to cylinder bore clearance to piston skirt diameter.

   Re-bored size calculation: D = A + B - C 

   where, 

   D: Bored diameter 

   A: Piston skirt diameter as measured 

   B: Piston to cylinder bore clearance (standard value) 

   C: Honing allowance 0.02 mm (0.0008 in) 

2. Install lower cylinder block, and tighten to the specified torque. Otherwise, cylinder bores may be distorted in final assembly.
3. Cut cylinder bores.
   NOTE:

   • When any cylinder needs boring, all other cylinders must also be bored.
   • Do not cut too much out of cylinder bore at a time. Cut only 0.05 mm (0.0020 in) or so in diameter at a time.
4. Hone cylinders to obtain the specified piston to cylinder bore clearance.
5. Measure the finished cylinder bore for out-of-round and taper.
   NOTE: Measurement should be done after cylinder bore cools down.