Piston-To-Bore Clearance

WARNING: This page is about a different car, the 2003 Nissan Pathfinder. However, it is still accessible from the selected car via links, so may be relevant.

Using a bore gauge, measure cylinder bore for wear, out-of-round and taper.
Cylinder bore inner diameter

Fig 1: Cylinder Bore Inner Diameter Chart
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 2: Using Bore Gauge Measuring Cylinder Bore
Courtesy of NISSAN MOTOR CO., U.S.A.

If it exceeds the limit, rebore all cylinders. Replace cylinder block if necessary.

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

Limit 0.015 mm (0.0006 in)

Taper (Difference between A and C):

Limit 0.015 mm (0.0006 in)
Check for scratches and seizure. If seizure is found, hone it.

Fig 3: Identifying Cylinder Bore Measuring Position
Courtesy of NISSAN MOTOR CO., U.S.A.
- If both cylinder block and piston are replaced with new ones, select piston of the same grade number punched on cylinder block rear position. These numbers are punched in either Arabic or Roman numerals.
  
  Fig 4: Identifying Cylinder Bore Grade Numbers
  Courtesy of NISSAN MOTOR CO., U.S.A.
Measure piston skirt diameter.
Piston diameter "A": Refer to SDS PISTON, PISTON RING AND PISTON PIN .

Measuring point "a" (Distance from the top):

41.0 mm (1.61 in)

Fig 5: Measuring Piston Skirt Diameter
Courtesy of NISSAN MOTOR CO., U.S.A.
Check that piston-to-bore clearance is within specification.
Piston-to-bore clearance "B":

0.010 - 0.030 mm (0.0004 - 0.0012 in)
Determine piston oversize according to amount of cylinder wear.
Oversize pistons are available for service.

Refer to SDS PISTON, PISTON RING AND PISTON PIN .
- If oversize piston is used, use it for all cylinders with oversize piston rings.
Cylinder bore size is determined by adding piston-to-bore clearance to piston diameter "A".
Rebored size calculation: D = A + B - C

where,

D: Bored diameter

A: Piston diameter as measured

B: Piston-to-bore clearance

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. Cut only 0.05 mm (0.0020 in) or so in diameter 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.