- inspect the crankshaft. Cracks anywhere on the crankshaft are not allowed. On surfaces mating with the working edges of the seals, scratches, nicks and marks are not allowed;
- make accurate measurements of the journals of the main and connecting rod bearings. When repairing, they can be reground up to three times with a decrease in diameter. After that, repair liners of increased thickness are installed;
Pic. 138. Measurement of the beating of the crankshaft in the region of the middle neck
- clamp the crankshaft between the holders of the lathe, or install the extreme main journals on two prisms (pic. 138) and check the runout on the main bearing journal with an indicator. The runout should not exceed 0.06 mm, otherwise the shaft should be replaced;
- measuring clearances in main and connecting rod bearings using a piece of plastic wire from the kit «Plastigage», carried out in the same way as for the VR6 engine (see paragraph 2.6.2);
- If there is no Plastigage plastic wire, then the runout of the main and connecting rod bearings can be measured in the following way:
- install the bearing caps together with the nested liners in the cylinder block and tighten the mounting bolts to 65 Nm. The bushings must be installed in their original locations;
- if the runout of connecting rod bearings is measured, then insert the liners into the connecting rods and connecting rod caps, and tighten the caps with old nuts to a torque of 30 Nm;
Pic. 139. Measuring the diameter of installed bearing shells. The measurement should be taken in directions A and B and also in directions 1 and 2
- measure the diameter of the installed bearing shells using a measuring device (pic. 139). Pay special attention to measuring directions A and B and measuring points 1 and 2. In this way, roundness irregularities can be detected (A and B), as well as conical (1 and 2). Record the measurements for each individual bearing;
Pic. 140. Measuring the diameter of the neck of the main bearing. In the same way, you can measure the diameter of the connecting rod journals
- Measure the diameters of all bearing journals with a micrometer. In doing so, pay attention to the measurement points (pic. 140, shown by arrows). Record the measurements for each bearing journal;
- runout of the main and connecting rod bearings and the difference between the measured inner diameters of the bearing bores and the diameters of the bearings.
Note. To check the runout of the connecting rod bearings, rotate the crankshaft and measure the next two connecting rod journals as described above.
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