Visually inspect the block for cracks and corrosion. Repair stripped threads in holes. It is recommended to check the tightness of the cylinder block in a car repair shop that has the appropriate equipment. If defects are found, repair the unit or replace it.
Check for scratches and burrs on the inner surfaces of the cylinders.
Pic. 3.36. Places for measuring the inner diameter of the cylinder: directly under the bead (X and Y), center and bottom
Measure the inner diameter of the cylinder at the top (right under the ridge), middle and bottom parallel to the axis of the crankshaft (pic. 3.36). Then take measurements at the same levels, but in a direction perpendicular to the axis of the crankshaft. Compare the measurement results with the values in the technical data. If there are severe scuffs and scratches on the surfaces of the cylinders, or the ovality and taper of the cylinders exceed the established maximum allowable values, take the block to an auto repair shop for boring and honing. After repair, pistons and rings of repair sizes will be needed.
If the condition of the cylinders is acceptable, the wear of the cylinder and the clearance between the cylinder and the piston do not exceed the established norms, then boring is not required. The only necessary operation is honing.
Install crankshaft bearing caps before honing (without bearings) and tighten the bolts to the required torque.
Pic. 3.37. The surface of the cylinder after honing should be covered with a grid of fine lines intersecting at an angle of about 60°
Honing requires a special device with fine grinding heads, a large amount of oil, rags and an electric drill. Clamp the tool into the electric drill, attach the grinding heads and insert the tool into the first cylinder. Lubricate the surface of the cylinder well with oil, turn on the electric drill and periodically move it up and down in the cylinder. On the surface of the walls of the cylinder, a network of thin lines should form, intersecting at an angle of about 60° (pic. 3.37).
Lubricate the surface of the cylinder liberally at all times. Do not remove tool while rotating. After turning off the drill, continue to move it up and down until it comes to a complete stop, then squeeze the legs of the tool with the grinding heads and remove it from the cylinder. Remove oil from the surface of the cylinder and repeat the operation on the remaining cylinders. If the device is not available, this operation can be performed at a car repair shop for a reasonable fee. Satisfactory results are obtained when using an emery wheel mounted on an electric drill, or even when performing the operation manually with sandpaper.
After honing, chamfer the upper edges of the cylinder with a small file to prevent the rings from seizing when the piston is installed.
The entire cylinder block must be re-washed with warm water and detergent to remove abrasive residue left after honing. Brush all channels and rinse with running water. After flushing, dry the cylinder block and apply spindle oil to all machined surfaces. Before assembly, store the unit under a plastic cover.