Measuring the inner diameter of a cylinder (VW Sharan 1)

Check whether the cylinder wear exceeds the maximum permissible value of 0.08 mm. To do this, measure the inner diameter of the cylinder with a special measuring device - a bore gauge in three zones - in the upper, middle and lower parts of the cylinder (Fig. 60) both in the transverse and longitudinal directions of the engine.

When measuring the upper and lower belts of the cylinder, you should step back 10 mm from their edges. Thus, when measuring the internal diameter of the cylinder, you need to take six measurements for each cylinder.

All obtained values should be recorded and compared with the values given in the adjustment and control table. If the maximum wear value of at least one of the cylinders is greater than 0.08 mm, bore all cylinders to the nearest repair size.

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





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

The difference between the measured piston diameter and its nominal value should not exceed 0.04 mm, otherwise it is necessary to install a piston with an increased diameter - a repair size. For the VR6 engine, pistons of repair sizes are manufactured with a diameter increased by 0.5 and 1.0 mm.

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To check the piston runout during its stroke, measure the piston diameter and the inner diameter of the cylinder. Calculate the difference between the obtained values for each cylinder. If the difference is greater than 0.08 mm, the cylinders should be bored, since the runout has reached the wear limit.