Install the crankshaft in the centers of the lathe or with the outer journals on the prisms. Using an indicator mounted near the central neck, measure the runout. If the runout is greater than 0.06, then the shaft should be replaced.
Measure the diameters of the main and connecting rod journals with a micrometer (in two mutually perpendicular directions). Enter the measurement results in the table. Determine which group the neck sizes belong to (nominal, 1, 2, 3 repair).
Determine the calculated clearance value, assuming that the diameter measured on the liners is equal to the diameter of the corresponding repair group - see the Table of Dimensional and Installation Data (table 3). If the calculated clearance is less than 0.8 mm for main bearings and 0.07 for connecting rod bearings, do not regrind the journals, but simply replace the bearings with new ones of the same group (although you can't change them). If the clearance is greater than 0.17 mm on the main journals and 0.1 mm on the crankpins, then the corresponding journals (either all main or all connecting rod) should be reground to the nearest repair diameter and used with new liners of the same group. Determine the ovality and their taper. Limit deviations should be considered 0.03 mm for ovality and 0.0 15 mm for taper. If the measurement results exceed those indicated above, the necks should be reground, even if their diameter has not yet reached the maximum allowable value.
After regrinding the shaft and purchasing new liners, it is necessary to measure the true value of the clearances in the main and connecting rod bearings for verification. To do this, clean the liners, put them in the sockets in the cylinder block, lay the crankshaft on all main journals and put pieces of plastic wire (pic. 84). Install the main covers with inserted bushings and tighten the bolts to a torque of 65 Nm, after which the shaft can no longer be rotated.
To measure the clearance in the connecting rod bearings, bring the connecting rod to the shaft neck and put pieces of plastic wire under the connecting rod cover, equipped with an insert. Tighten the connecting rod cap nuts to a torque of 30 Nm, but in this case they should not be tightened by another 900. Since the shaft cannot be rotated, the clearance can only be measured on the two connecting rod journals in the BDC position.
Remove the main bearing caps and both connecting rod bearing caps.
Measure the width of the cut out pieces of calibrated wire on the scale (see fig. 84). The width value is numerically equal to the clearance in the bearing. If this gap is greater than 0.03-0.08 mm for main bearings and 0.02-0.07 mm for connecting rod bearings, then the corresponding bearings must be replaced.
Then you should turn the crankshaft and take measurements on the remaining connecting rod journals. Measurements should be made in the same way. If the gap exceeds the allowable value, replace the appropriate set of liners, and then measure the gaps again, they should be within the allowable range.
For reground journals and new liners, the clearance should be in the range of 0.03-0.08 mm for main bearings and 0.02-0.07 for connecting rod bearings. If the values of these gaps are greater than these indicated, but less than 0.17 and 0.1 mm, respectively, the engine can be operated, however, this indicates that the diameters of the shaft journals during grinding are reduced more than the norm. If the gap is greater than these values, the necks should be reground.
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