Crankshaft
Inspect the crankshaft. Cracks anywhere on the crankshaft are not allowed. Scratches, nicks and risks are not allowed on surfaces mating with the working edges of the stuffing boxes. The crankshaft is installed with extreme main journals on two prisms and the runout is checked with an indicator in the places indicated in Fig. 10, a. The numbers in the figure show the allowable beating and mixing of the necks.
Measure the diameters of the main and connecting rod journals. The journals should be ground when worn to a diameter of 0.005 mm less than the minimum diameter for a given crankshaft size, and also if the ovality of the journals is more than 0.03 mm or they have scuffs and risks. The diameters of the necks of normal size are given in Table. 2, and repair dimensions diameters (reduced by 0.25; 0.5; 0.75 and 1.00 mm) given above in sec. 1.4.1.
Grind the necks with a decrease to the nearest repair size. The distance between the axes of the connecting rod and main journals must be such that the piston stroke is within (66±0,125) mm. The radii of the fillets of the necks should be 2.8-3 mm.
The ovality and taper of the main and connecting rod journals after grinding should be no more than 0.007 mm, and the displacement of the axes of the connecting rod journals from the plane passing through the axes of the connecting rod and main journals should be no more than±0.35 mm (see fig. 10.5). To check, install the shaft with extreme main journals on prisms and set the shaft so that the axis of the connecting rod journal of the 1st cylinder is in a horizontal plane passing through the axis of the main journals. Then the indicator checks the displacement in the vertical direction of the crankpins of the 2nd, 3rd and 4th cylinders relative to the crankpin of the 1st cylinder. After grinding the necks, polish them with diamond paste or GOI paste.
After grinding and subsequent finishing of the necks, the plugs of the oil channels are removed, and then the nests are driven (socket diameter 10-0,036 mm) plugs with a countersink A.94016/10, put on the mandrel A.94016. The crankshaft and its channels are thoroughly washed to remove abrasive residues and blown with compressed air. Having completed these operations, new plugs are pressed in and each is minted at three points with a center punch.
On the first cheek of the crankshaft mark the amount of reduction of the main and connecting rod journals (for example, K 0.25; Ш 0.50).
Bearing shells
In the presence of scratches, scoring, delamination or increased wear, the liners are replaced. No fitting operations should be carried out on the liners. If, when checking the liners, it turns out that their further use is possible, then the gap between them and the crankshaft journals is checked. The gap can be determined by calculation by measuring the diameters of the necks, beds under the liners and the thickness of the liners. In the event that the gap exceeds the maximum allowable, equal to 0.15 mm for the main and 0.10 for the connecting rod journals, replace the liners with others with increased thickness after grinding the journals. A sign of the correct assembly and mating of the necks with the corresponding liners is the free rotation of the crankshaft.
Oil seals
Two self-locking oil seals ensure tightness at both ends of the crankshaft. When repairing the engine, it is recommended to replace both crankshaft oil seals, regardless of their condition.
Thrust half rings
As well as on liners, no fitting operations can be performed on half rings. In case of scuffing and delamination, the half-rings are replaced with new ones. Half rings are also replaced if the axial clearance of the crankshaft exceeds the maximum allowable - 0.35 mm. New half rings are selected with a nominal thickness or increased by 0.127 m in order to obtain an axial clearance of 0.06-0.26 mm.
The axial clearance of the crankshaft is checked using an indicator, as shown in rice. 51b.
Flywheel
Check the condition of the crown teeth. In case of damage, the flywheel is replaced.
flywheel surfaces (pic. eleven), mating with the crankshaft and the clutch disc, must not have scratches and burrs. Permissible flatness is not more than 0.1 mm.
If there are scratches on the working surface 2 of the flywheel under the clutch disc, this surface is machined, removing a metal layer of no more than 1 mm and ensuring roughness. Surface 1, bearing dimension D= (0,5±0,1) mm and ensuring the parallelism of surfaces 2 and 2 relative to surface 3. The permissible non-parallelism, measured at the extreme points of surfaces 2 and 2, should not exceed 0.1 mm.
The runout of the bearing surface 2 of the clutch driven disk and the clutch mounting plane 2 is checked by installing the flywheel on a mandrel ∅ 35 mm and centering it along the mounting hole with emphasis on plane 3. At points A and B, the indicator should not show beats exceeding 0.1 mm.