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Measuring cylinder liners
To measure the cylinder liners in the middle and lower part requires a special indicator for the measurement of cylinders (bore gauge). Without this device works listed below will be impossible to perform.
| Fig. 55. Designated metering holes of cylinder liners: A - measured in the longitudinal axis of the engine; In - measured in the transverse axis of the engine; and - the highest point of stopping the top piston ring; b - lower stop point of the piston; from - the lowest point of stopping oil ring; 1, 2, 3 - Measuring point
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| Fig. 56. Measuring the cylinder bores using Nutromer
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Holes cylinder liners have been measured in the longitudinal and transverse axes, as shown in Fig. 55. If these works are carried out with the engine mounted on the vehicle, then the third measuring point is located directly above the piston stopped at the BDC. The other two measurement points lie respectively above. Nutromer lowered into the liner, as shown in Fig. 56. In total, on each cylinder liner is necessary to perform measurements at 6. The results of all measurements must be accurately recorded and then compare with the technical data (see. App. 1). It should be remembered that in case of detection of dimensional deviations on at least one cylinder, all cylinders it will be necessary to chisel. Dimensional deviation of 0.20 mm from the nominal, either in the longitudinal or transverse axis is permissible. If the wear exceeds acceptable limits, in this case it is possible to replace the cylinder liner. This work should only be carried out at a specialized service stations.
| Fig. 57. Measuring the diameter of the piston
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Finally, the size of the cylinder bore is determined by the sum of the diameter of the piston, measured 10 mm from the bottom edge of the piston skirt and the clearance of the working piston, which ranges from 0.017 to 0.043 mm. In Fig. 57 shows the location of the mic. You also need to take into account the allowance for honing cylinders, which should be 0.03 mm. Working backlash of the piston must not deviate from the target by more than 0.12 mm. To check the working air gap is necessary to measure dimensions of the piston and the piston bore of the cylinder liner as described above, and the difference of the results of measurements for each pair of piston-cylinder assembly. If the result is greater than 0.12 mm, it is necessary to bore the cylinders or install new cylinder liners, because the working air gap has reached the limit of wear.
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