Piston To Cylinder Bore Clearance

Cylinder Bore inner Diameter 

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

  Courtesy of NISSAN NORTH AMERICA, INC.

  f	: 10 mm (0.39 in)
  g	: 60 mm (2.36 in)
  h	: 120 mm (4.72 in)

  Wear limit:	Refer to Cylinder Block .
  Out-of-round (Difference between "A" and "B"):
  Taper limit (Difference between "C" and "E"):

• 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.
• Oversize piston is provided. When using oversize piston, re-bore cylinder so that the clearance of the piston-to-cylinder bore satisfies the standard.
  CAUTION: When using oversize piston, use oversize pistons for all cylinders with oversize piston rings.

  Oversize (O/S)

  : 0.2 mm (0.008 in)

Piston Skirt Diameter 

Measure the outer diameter of piston skirt with a micrometer (A).

Courtesy of NISSAN NORTH AMERICA, INC.

Piston-to-Cylinder Bore Clearance 

Calculate by piston skirt diameter and cylinder bore inner diameter [direction (B), position (D)].

Courtesy of NISSAN NORTH AMERICA, INC.

(Clearance) = (Cylinder bore inner diameter) - (Piston skirt diameter).

• If the calculated value exceeds the limit, replace piston and piston pin assembly. Refer to Cylinder Block .

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 main bearing cap, 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 finished cylinder bore for the out-of-round and taper.
   NOTE: Perform measurement after cylinder bore cools down.