Checking the axial movement of the crankshaft
1. Fix on the block of cylinders the holder with the pointer indicator MKM-571-B, the contact pin of which should rest against the end of the shaft fixed in the block with bearings (see illustration).
2. Move the crankshaft in the longitudinal direction. The maximum allowable axial movement of the crankshaft must be within 0.01-0.02 mm.
Checking the runout of the crankshaft
3. Unscrew bolts of fastening of covers of radical bearings and remove covers.
4. Fix on the block of cylinders the holder with the pointer indicator MKM-571-B, the contact pin of which should rest against the end of the shaft (see illustration 11.1).
5. Rotate the crankshaft and read the dial indicator. In the same way, check the runout of the surfaces of the crankshaft journals (see illustration).
Permissible value of ovality is 0.03 mm. Clearance between the shells and the necks of the main bearings of the crankshaft. Measurement with a calibrated plastic wire «Plastigage»
The gap between the liners and the necks of the main bearings of the crankshaft is checked by calculation by measuring the details. Before this, the crankshaft and its necks are cleaned, and the liners are lubricated with a thin layer of engine oil.
Usually, a calibrated plastic wire is used to check the gap.
6. Clean the working surface of the earbuds and the corresponding neck and place a piece of plastic wire on its surface (see illustration).
7. Install the main bearing cap on the journal to be checked, and tighten the mounting bolts to the specified torque.
8. Unscrew the bolts and remove the bearing cover, and then, using the scale on the plastic wire package, determine the gap size by flattening the wire (see illustration). The allowable gap between the liners and covers is 0.016-0.069 mm.
Measuring the clearance of connecting rod bearings with a caliper
In this case, the clearance between the connecting rod bearing shells is determined by measuring the bearing diameter with a caliper at three points. The results obtained are summarized and divided by 3. As a result, the average value of the diameter is obtained (see illustration 11.8a).
Example:
I - the result obtained when measuring at point I - 54.972 mm
II - the result obtained when measuring at point II - 54.981 mm
III - the result obtained when measuring at point III - 54.984 mm
164.937 mm: 3 = 54.979 mm
9. Measure the diameter of the respective connecting rod journal at two points with a micrometer, sum the values obtained and divide them by 2.
Example:
I - the result obtained when measuring at point I - 54.962 mm
II - the result obtained when measuring at point II - 54.964 mm
109.926 mm: 2 = 54.963 mm
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