Cylinder and Piston
CYLINDER AND PISTON1) Using a cylinder bore gauge, check the inner diameter of cylinder liner, cylindricality, out-of-roundness. If it is not within the standard, perform boring and honing, or replace the cylinder block and piston as a set. For boring and honing procedure, refer to step 3).
NOTE:
^ Measurement should be performed at a temperature of 20°C (68°F).
^ Measure the inner diameter of each cylinder liner in both the thrust and piston pin directions at the heights as shown in the figure.
^ The cylinder bore size is stamped on the upper face of the cylinder block.
Inner diameter of cylinder liner:
Standard
A: 94.005 - 94.015 mm (3.7010 - 3.7014 in)
B: 93.995 - 94.005 mm (3.7006 - 3.7010 in)
Cylindricality:
Standard
0.015 mm (0.0006 in)
Out-of-roundness:
Standard
0.010 mm (0.0004 in)
2) Check the clearance between cylinder liner and piston. Check the clearance between cylinder liner and piston by measuring respectively the inner diameter of cylinder liner and the outer diameter of piston.
NOTE:
For the measurement of the inner diameter of cylinder liner, refer to step 1).
(1) Check the outer diameter of piston with a micrometer. If it is not within the standard, replace the piston.
NOTE:
^ Measurement should be performed at a temperature of 20°C (68°F).
^ Measure the outer diameter of each piston in thrust direction at the height as shown in the figure.
^ Standard sized pistons are classified into two grades, "A" and "B". These grades should be used as guide lines in selecting a standard piston.
^ If the piston is replaced, check the clearance between cylinder liner and piston in the step (2), and select a suitable sized piston.
Piston grade point H:
13.3 mm (0.52 in)
Piston outer diameter:
Standard size
Standard
A: 93.980 - 93.990 mm (3.7000 - 3.7004 in)
B: 93.970 - 93.980 mm (3.6996 - 3.7000 in)
0.25 mm (0.0098 in) oversize
Standard
94.220 - 94.240 mm (3.7094 - 3.7102 in)
0.50 mm (0.0197 in) oversize
Standard
94.470 - 94.490 mm (3.7193 - 3.7201 in)
(2) Calculate the clearance between cylinder liner and piston. If it is not within the standard, perform boring and honing, or replace the cylinder block and piston as a set. For boring and honing procedure, refer to step 3).
Clearance between cylinder liner and piston at 20°C (68°F):
Standard
0.015 - 0.035 mm (0.00059 - 0.00138 in)
3) Boring and honing
(1) If any of the inner diameter, cylindricality, out-of-roundness or cylinder-to-piston clearance is out of standard or if there is any damage on the cylinder liner, rebore it to replace with an oversize piston.
CAUTION:
When any of the cylinder liner needs reboring, all other cylinder liners must be bored at the same time, and replaced with oversize pistons.
(2) If the inner diameter of cylinder liner exceeds the limit after boring and honing, replace the cylinder block and piston as a set.
NOTE:
^ Immediately after reboring, the inner diameter of cylinder liner may differ from its real diameter due to temperature rise. Thus, when measuring the inner diameter of cylinder liner, wait until it has cooled to normal temperature.
^ For the measurement of the inner diameter of cylinder liner, refer to step 1).
Inner diameter of cylinder liner boring limit (diameter):
To 94.505 mm (3.7207 in)