Piston: Testing and Inspection

When performing repairs, the pistons with the code letters stated below should be installed in the case of cylinder bores with "standard size".





Cylinder Bore ID Piston ID (see footnote [1])
A A or X
X X or A, B
B B or X

NOTE: When performing repairs, the cylinder bores should be finished to the dimensions of the existing pistons in accordance with the table for matching the pistons; see "Measuring, boring and honing cylinder bores". Piston play when the pistons are new is 0.02 - 0.04 mm. The measuring point is about 12 - 14 mm above the bottom edge of the piston at right angles to the piston pin. It is not possible to conduct an exact measurement of used pistons as the piston skirt has "sunk" at the measuring point provided.

[1]: If pistons with standard size are replaced when performing repairs because of a noise problem, match up the pistons properly in accordance with the cylinder bore identification.
Additional codes when ordering pistons 52 = A, 54 = X and 56 = B.