Removal
Note: Removal of the crankshaft is only possible after dismantling the engine. In this case, you must first remove the drive disk, crankshaft pulley, oil pan, drive chain, and pistons/rods. Unscrew the mounting bolts and remove the rear oil seal holder from the cylinder block.
1. Before removal, check the axial play of the crankshaft. Install the meter with a dial indicator so that its rod is in contact with the end surface of the shaft (see illustration).
10.1. Checking crankshaft endplay using a dial gauge
2. Move the crankshaft back all the way and set the meter indicator to zero, then move the shaft forward all the way and take the meter readings. The distance the crankshaft moves is its axial play. The gap should be 0.076-0.254 mm. If the amount of play exceeds this value, the thrust surfaces of the crankshaft should be inspected for wear. If the degree of wear of the thrust surfaces is acceptable, excessive axial play of the shaft is eliminated by installing new main bearings.
3. If you do not have a gauge with a dial indicator, you can use feeler gauges to measure gaps. Move the crankshaft forward as much as possible. By measuring the clearance between the crankshaft and the face of the main bearing thrust surface using feeler gauges, determine the shaft end play (see illustration).
10.3. Checking the axial play of the crankshaft by measuring with a feeler gauge on the thrust bearing journal
4. Alternately loosen the main bearing cap bolts a quarter turn at a time until they can be unscrewed by hand.
5. It is necessary to remove the reinforcing element, then check for the presence of location marks on the main bearing caps. If necessary, number the bearing caps starting at the front of the engine and mark each with an arrow pointing forward. Remove the bearing caps. If the bearing shells remain in the caps, try to prevent them from falling out when removing them.
6. Carefully remove the crankshaft from the cylinder block. Since the shaft has significant weight, it is recommended to have an assistant. With the bearing shells in the block and covers, install the covers and the reinforcing element and tighten the fastening bolts with your fingers. Ensure that the main bearing caps are positioned correctly. The arrows on the covers should point forward.
Installation
7. Installing the crankshaft is the first and one of the most important stages of engine assembly. At this stage it is assumed that the cylinder block and crankshaft have been cleaned, inspected and, if necessary, rebuilt or repaired.
8. Install the motor with the base facing up.
9. Unscrew the mounting bolts and remove the reinforcing element and main bearing caps.
10. Remove the pre-installed main bearing shells from the cylinder block and covers. Wipe the bearing seats with a clean cloth. Ensure that the bearing housings are extremely clean as this is essential for accurate oil clearance measurements.
Checking the main bearing oil clearance
11. Clean the backs of the new upper main bearing shells and install them in their respective locations in the cylinder block. Upper (block-mounted) The liner has a groove and an lubrication hole.
Caution: The oil holes in the cylinder block and upper bearing shells must be aligned.
Thrust bearings or washers are installed on the fifth journal of the crankshaft (when counting from the front). Clean the back of the lower main bearing shells and place them on the corresponding cap journals. Make sure that the protrusions of the liners fit into the recesses of the covers or cylinder block. The upper liners, which have holes, are installed in the cylinder block, and the lower, solid ones - in the covers.
Caution: Do not install the bearings with a hammer, and do not damage the bearing surfaces. At this stage, do not use any lubricant during the installation process.
12. Clean the bearing mating surfaces on the cylinder block and on the crankshaft journals with a clean, lint-free cloth.
13. If necessary, clean the crankshaft lubrication holes as dirt from the holes may get onto the new bearings.
14. After thorough cleaning, carefully install the crankshaft into the cylinder block.
15. Before final installation of the crankshaft, the oil clearance of the main bearings should be checked.
16. Cut several pieces of plastic indicator of a suitable size (the sections should be slightly shorter than the width of the main bearing shells).
17. Place one piece on each main journal parallel to the shaft axis (see illustration).
10.17. Place the indicator strips on the end of the journal parallel to the axis of the crankshaft
18. Clean the mating surfaces of the liners in the covers or lower crankcase. While holding the liners, install the covers or crankcase onto the crankshaft and cylinder block. Do not allow the plastic indicator sections to move. Make sure the arrows on the installed main caps point forward, then install the reinforcement.
19. Before installation, lubricate the threads of the old bolts with engine oil and tighten them with your fingers. Gradually tighten the bolts to the required torque, starting with the center fasteners and moving to the outer bolts. Do not allow the crankshaft to turn.
20. Unscrew the bolts in the reverse tightening sequence and carefully remove the reinforcing element and main bearing caps. Covers must be removed in a strictly vertical direction. Do not allow the indicator bars to shift or the crankshaft to rotate.
21. Compare the width of the crushed section of the indicator on each main journal with the scale diagram that comes with the indicator, and determine the size of the oil gap (see illustration). Make sure that the obtained clearance values correspond to the norm. Check the size of the oil gap by contacting the company station.
10.21. Compare the width of the crushed section of the indicator with the scale diagram and determine the size of the oil gap (To determine the gap, compare the widest part); make sure that the gap was determined according to the appropriate diagram - the indicator is equipped with an inch and metric scale
22. If the gap is not within the standard, it should be assumed that the size of the liners is mismatched (which means they need to be replaced). Before deciding to replace the liners, make sure that when measuring the gap between the surfaces of the covers, the cylinder block and the liners, there was no dirt or a layer of lubricant. If the indicator expands at one of its ends, it means that the main journal has a taper. If the gap exceeds the permissible limit, the liners should be replaced with parts of a reduced size.
Caution: when installing a new crankshaft, be sure to use bearings of the nominal size.
23. Carefully remove any remaining plastic indicator from the surfaces of the main journals and/or bearing shells. Clean off any traces of indicator with your fingernail or the edge of a plastic card, being careful not to damage the bearing surfaces. If necessary, clean the lubrication holes.
Final installation of the crankshaft
24. Carefully remove the crankshaft from the cylinder block.
25. Clean the mating surfaces of the bearing shells in the cylinder block, then coat them with a thin, uniform layer of molybdenum disulfide-based lubricant or assembly oil. Make sure that the working and thrust surfaces of the thrust bearing are lubricated.
26. Make sure that the surfaces of the crankshaft journals are clean and install it into the cylinder block.
27. Clean the mating surfaces of the bearing shells, then lubricate them. Clean the surfaces of the cylinder block and bearing caps.
28. Install the main covers and the reinforcing element.
29. Before installation, lubricate the bolt threads with engine oil and tighten them with your fingers.
30. Tighten the main bearing cap bolts to the required torque (tightening should begin with the central bolts and proceed to the outer fasteners).
31. You should check the crankshaft endplay using a set of feeler gauges or a dial gauge. If the thrust surfaces of the crankshaft are not damaged or excessively worn, then after installing new bearings, its axial play should be normal.
32. Rotate the crankshaft by hand to ensure that it rotates smoothly and smoothly. The shaft rotation should occur when applying a torque of no more than 6 Nm (before installing pistons/rods). If more torque is required to turn, determine the cause of this discrepancy.
33. Install a new crankshaft rear oil seal (see chapter 2A).