Block and Piston Inspection
Block and Piston Inspection1. Check the piston for distortion or cracks.
2. Measure the piston diameter at a point 16.0 mm (0.63 inch) from the bottom of the skirt.
3. Measure wear and taper in directions X and Y at three levels in each cylinder.
- If the bore size or taper in any cylinder is over the service limit, the block must be rebored. If the measurements in any cylinder are beyond the oversize bore service limit, replace the cylinder block.
Oversize
0.25: 89.250 - 89.265 mm (3.5138 - 3.5144 inch)
0.50: 89.500 - 89.515 mm (3.5236 - 3.5242 inch)
Reboring Limit: 0.5 mm (0.02 inch)
Bore Taper Limit: (Difference between first and third measurement) 0.05 mm (0.002 inch)
4. Scored or scratched cylinder bores must be honed.
5. Check the top of the cylinder block for warpage. Measure along the edges and across the center.
6. Calculate the difference between cylinder bore diameter and piston diameter.
Cylinder Honing
1. Measure the cylinder bores. If the cylinder block is to be reused, hone the cylinders and remeasure the bores. Only scored or scratched cylinder bores must be honed.
2. Hone the cylinder bores with honing oil and a fine (400 grit) stone in a 60 degree crosshatch pattern.
NOTE: Use only a rigid hone with 400 grit or finer stone, such as Sunnen, Ammco, or equivalent. Do not use stones that are worn or broken.
3. When honing is complete, thoroughly clean the cylinder block of all metal particles. Wash the cylinder bores with hot soapy water, then dry and oil them immediately to prevent rusting. Never use solvent, it will only redistribute the grit on the cylinder walls.
4. If scoring or scratches are still present in the cylinder bores after honing to the service limit, rebore the cylinder block. Some light vertical scoring and scratching is acceptable if it is not deep enough to catch your fingernail and does not run the full length of the bore.