Piston: Testing and Inspection

Block and Piston Inspection

1. Remove the pistons from the engine block Crankshaft and Piston Removal.

2. Check the pistons for distortion or cracks.

3. Measure the piston diameter at a point 13 mm (0.51 in) from the bottom of the skirt. There are two standard-size pistons (No Letter or A, and B). The letter is stamped on the top of the piston. Letters are also stamped on the engine block as the cylinder bore sizes.






















4. Measure the wear and taper in direction X and Y at three levels inside each cylinder as shown. If measurements in any cylinder are beyond the oversize bore service limit, replace the engine block. If the engine block is being rebored, refer to step 7 after reboring.

























5. Hone any scored or scratched cylinder bores Cylinder Bore Honing.

6. Check the top of the engine block for warpage. Measure along the edges and across the center as shown.














7. Calculate the difference between the cylinder bore diameter and the piston diameter. If the clearance is near or exceeds the service limit, inspect the piston and the cylinder bore for excessive wear.