Measurement of the internal diameter of the cylinder

Check does not exceed the maximum allowable wear cylinders - 0.08 mm. To measure the inside diameter of which cylinder a special measuring instrument - nutrometrom in three zones - the top, middle and bottom of the cylinder (Fig. 60) in both transverse and longitudinal directions of the engine.

When measuring the upper and lower zones of the cylinder should be 10 mm to retreat from their edges. Thus, when measuring the internal diameter of the cylinder, it is necessary to hold the six measurements for each cylinder.

All the values obtained should be recorded and compared with the values in the table of adjustment and control. If the maximum amount of wear of at least one of cylinders of more than 0.08 mm - chisel all cylinders to the next oversize.

To determine the measure diameter of the cylinder bore of the piston to the resulting value add another 0.03 mm, due to runout of the piston in its course, and in addition, add 0.02 mm for final honing the cylinder.

The piston has a complicated shape of the outer surface. Therefore, the diameter of the piston is measured by a micrometer at a distance of 6 mm from the edge of the piston skirt and at right angles to the bores for the piston pin (Fig. 61).

The difference between the measurement of the diameter of the piston and the nominal value must not exceed 0.04 mm, otherwise you need to install the piston with a larger diameter - the size of the repair. For engine pistons VR6 repair sizes are produced with an increase of 0.5 and 1.0 mm in diameter.

To test the run-out of the piston during its course, measure the diameter of the piston and an inner diameter of the cylinder. Calculate the difference between the values obtained for each cylinder. If the difference is more than 0.08 mm, the cylinders should be chiseled as heartbeat reached deterioration borders.