To measure piston backlash, measure the diameter of the pistons (pic. 90) and record the measurement results. To measure backlash, measure the diameter of the cylinders as follows:
- Using a cylindrical dial indicator, measure the diameter at a distance of 10 mm from the top edge of the cylinder and then 10 mm from the bottom edge (Pic. 89).
- Additionally, take a measurement in the middle.
- Make the above measurements in the longitudinal direction and then take measurements again at the same depths in the transverse direction of the block. Record all six results. The difference between the upper and lower dimensions characterizes the taper. The difference between measurements in the longitudinal and transverse directions characterizes the ovality. For all measurements, the diameter should not differ from the specified value by more than 0.20 mm.
There are oversized pistons and the block can be bored out for them.
The skew of the surface of the cylinder block is controlled in the same way as checking the cylinder head, as shown in Figure 54. Measure the block in the longitudinal, transverse direction and diagonally. A probe thicker than 0.05 mm should not pass through.