Cylinders
The clearance between the cylinder and the piston should be within 0.038-0.0635 mm. Check the surface condition, ovality and taper of the cylinders by measuring the diameter in three planes, in directions parallel and perpendicular to the axis of the block. Taper (difference between the diameters at the top and bottom of the cylinder, measured in the same direction) should not exceed 0.305 mm. The ovality of the cylinder is due to the difference in the loads on the wall in the direction perpendicular to the axis of the engine. Compare the results of measurements with the results of measurements of the piston diameter.
Crankshaft
Check the condition of the crankshaft journals. Necks should have a mirror surface. Check the roughness of the necks by rubbing them with your fingernail. Minor signs of wear are allowed.
Measure the diameter of the necks in several places and determine the taper and ovality.
Permissible taper and ovality are 0.0127 mm. If all dimensions are normal, then the crankshaft should only be polished before installation.
Pistons
Check for cracks in the piston. The piston should move freely along the finger and rotate on it, but there should not be a noticeable gap (piston pin is pressed into the piston). The clearance is checked by rocking the piston relative to the pin in a plane passing through the axis of the pin and the connecting rod. Permissible finger clearance in the connecting rod bushing is 0.025-0.051 mm. Measure the piston diameter along the axis of the pin and in a perpendicular direction. The difference between the diameter of the cylinder and the piston gives the gap between them. If the clearance and diameter of the piston correspond to the norm, then the piston can be installed. If the piston diameter is correct, but the cylinder diameter is not, then the piston should be replaced. If the cylinder diameter exceeds the norm, then it should be bored out, and the pistons should be replaced with repair ones. Typically, if two or more pistons (cylinder) are worn out, then the cylinder should be bored out, and the pistons should be replaced with repair ones in the kit.
Connecting rods
Check the deformation of the connecting rods. Replace the connecting rod if bent or propeller is found. If the clearance in the connecting rod bush is correct and there is no damage to the connecting rod, then check the inner diameter of the connecting rod bearings by inserting them into the connecting rod and cap and tightening the nuts (bolts) covers with a given moment. If the clearance in the connecting rod neck of the crankshaft is not correct (determined by subtracting the diameter of the respective crankpin), then replace the bearing shells with new ones and check the diameter again. If the clearance is still not correct, and the diameter of the crankshaft journal is correct, then the connecting rod must be repaired or replaced.
Bearings
If severe bearing wear, deep grooves, pits or overheating marks are found, the bearing and the corresponding shaft should be taken to a car service for inspection. For removing ring bearings (e.g. balance shaft, camshafts, drive shafts of engine units), pressed into the cylinder block, the block should be handed over to a car service, as special equipment is required.
Oil pump
Disassemble the pump and check the condition of the gears and casing. Check the freedom of movement of the pressure reducing valve plunger. If all parts are in satisfactory condition, then lubricate all parts and assemble the pump.