PISTON INSPECTION
PISTON INSPECTION
SM2841686
id011000502100
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Caution
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• If the piston is replaced, replace the piston, piston pin, and the snap ring as a single component.
1.Measure the piston outer diameter using the micrometer.
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• The measurement position is 12.0 mm {0.472 in} from the lower end of the piston (area with no coating on the piston skirt) and in the thrust direction.
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― If it is not within the specification, replace the piston.
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Standard piston outer diameter
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88.965—88.995 mm {3.5026—3.5037 in}
2.Measure the cylinder bore diameter. (See CYLINDER BLOCK INSPECTION.)
3.Calculate the cylinder-to-piston clearance from the cylinder bore diameter and the piston outer diameter.
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• If the clearance exceeds the maximum specification, replace the piston or cylinder block.
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Standard clearance between piston and cylinder
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0.0250—0.0450 mm {0.00099—0.00177 in}
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Maximum clearance between piston and cylinder
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0.066 mm {0.0026 in}
4.Measure the piston-to-ring groove clearance along the perimeter using a feeler gauge. For the O-ring, measure the clearance with the O-ring assembled to the piston.
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• If the clearance exceeds the maximum specification, replace the piston or piston ring.
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Standard clearance between piston ring and ring groove
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Top: 0.04—0.08 mm {0.0016—0.0031 in}Second: 0.03—0.07 mm {0.0012—0.0027 in}Oil: 0.03—0.09 mm {0.0012—0.0035 in}
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Maximum clearance between piston ring and ring groove
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Top: 0.12 mm {0.0047 in}Second: 0.10 mm {0.0039 in}Oil: 0.17 mm {0.0067 in}