Service Limits & General Specifications
PISTON AND PISTON PIN CLEARANCEInner Diameter of Piston Pin Hole
^ Measure the inner diameter of piston pin hole "dp".
Standard diameter "dp"
Grade No. 0 21.993 - 21.999 mm (0.8659 - 0.8661 inch)
Grade No.1 21.999 - 22.005 mm (0.8661 - 0.8663 inch)
Outer Diameter of Piston Pin
^ Measure outer diameter of piston pin "Dp".
Standard diameter "Dp"
Grade No. 0 21.989 - 21.995 mm (0.8657 - 0.8659 inch)
Grade No.1 21.995 - 22.001 mm (0.8659 - 0.8662 inch)
Piston and Piston Pin Interference Fit
Standard Interference Fit= "Dp - "dp"
Standard 0.002 mm - 0.006 mm (0.0001 - 0.0002 inch)
^ If clearance is exceeds specification, replace piston/piston pin assembly and connecting rod assembly with reference to specification of each part.
^ When replacing piston/piston pin assembly, refer to "PISTON-TO-CYLINDER BORE CLEARANCE".
PISTON-TO-CYLINDER BORE CLEARANCE
1. Using a bore gauge, measure cylinder bore for wear, out-of-round and taper. The X axis is in the longitudinal direction of the engine.
Cylinder bore inner diameter
If it exceeds the limit, re bore all cylinders. Replace cylinder block if necessary.
Out-of-round (Difference between X - Y) less than 0.015 mm (0.0006 inch)
Taper (Difference between, C - A) less than 0.015 mm (0.0006 inch)
2. Check for scratches and seizure. If seizure is found, hone it.
^ 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.
3. Measure piston skirt diameter.
Piston diameter "A" : Refer to "PISTON. PISTON RING AND PISTON PIN.
Measuring point "a" (distance from the top) 41.0 mm (1.614 inch)
4. Check that piston-to-bore clearance is within specification.
Piston-to-bore clearance at "B" 0.010 - 0.030 mm (0.0004 - 0.0012 inch)
^ The piston-to-bore clearance is measured at the "B" level in the cylinder as shown.
5. Determine piston oversize according to amount of cylinder wear.
^ Oversize pistons are available for service.
^ If oversize piston is used, use it for all cylinders with oversize piston ring. Refer to "PISTON, PISTON RING AND PISTON PIN ".
6. 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 inch)
7. Install main bearing caps, and tighten to the specified torque. Otherwise, cylinder bores may be distorted after boring.
8. 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 inch) or so in diameter at a time.
9. Hone cylinders to obtain specified piston-to-bore clearance.
10. Measure finished cylinder bore for out-of-round and taper.
^ Measurement should be done after cylinder bore cools down.