- inspect the crankshaft. Cracks in any place of the crankshaft are not allowed. Scratches, nicks and marks are not allowed on the surfaces mating with the working edges of the seals;
- make precise measurements of the main and connecting rod bearing journals. During repairs, they can be reground up to three times with a reduction in diameter. After this, thicker repair liners are installed;
- clamp the crankshaft between the lathe holders (or install the outer main journals on two prisms) and check the runout on the main journal of the middle support with an indicator. The runout should not exceed 0.06 mm, otherwise the shaft should be replaced;
- measure the clearances in the main and connecting rod bearings, for which:
Fig. 83. Placement of plastic wire for measuring clearance in main or connecting rod bearings
- thoroughly clean the working surfaces of the liners and the corresponding neck and place a piece of plastic wire on the surface of the neck (Fig. 83);
- install the connecting rod with the cap or the main bearing cap on the journal, depending on the type of journal being checked, and tighten the nuts or bolts. Tighten the connecting rod bolt nuts to a torque of 30 N·m, and the main bearing cap bolts to a torque of 30 N·m;
Fig. 84. Measuring the clearance in the main or connecting rod bearings
- remove the cover and, using the scale of the measuring ruler included in the Plastigage flattening kit, determine the size of the gap at the widest point of the plastic wire (Fig. 84);
- if the gap is less than the maximum, these liners can be used again. If the gap is greater than 0.1 mm, replace the liners on these journals with new ones. If the crankshaft journals are worn and ground to the repair size, replace the liners with repair ones (increased thickness).
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