Withdrawal
Remove the cylinder head, toothed belt, front cover, flywheel, pistons and crankshaft.
Examination
Cylinder block
1. Remove all gaskets, sealant, dirt, oil, grease and other foreign matter from the engine block. Visually check the cylinder block for rust, corrosion, cracks or other defects.
2. Measure the diameters of the cylinders in diametrically opposite directions (A and B), in three planes along the height of the cylinders (1, 2 and 3).
3. If the cylinder diameters exceed the allowable values, have an ovality or taper, or the surface of the cylinders is damaged or has a wear, the cylinder block must be bored and honed, and new oversized pistons and piston rings must be installed.
- Nominal cylinder diameter: 83 0.03 mm
- Cylinder taper: no more than 0.01 mm
4. If there is a step on the top of the cylinder, cut it off with the special tool.
5. Four oversized piston sizes are available as spare parts: 0.25, 0.5, 0.75 and 1.00mm. When boring cylinders to the nearest oversize, keep the clearance between the piston and cylinder and make sure the pistons are the same oversize. The standard measurement of the outer diameter of the piston must be taken at a distance of 2 mm from the skirt and perpendicular to the thrust surfaces. Clearance between piston and cylinder: 0.069–0.091 mm.
6. Check up the block of cylinders on absence of damages and cracks.
7. Clear mating surfaces of a head of the block of cylinders and the block of cylinders of the lining remains. With a metal ruler and feeler gauge in six directions, check the flatness of the mating surface of the cylinder block.
Flatness deviation:
- in width: 0.042 mm;
- lengthwise: 0.096 mm;
- diagonal: 0.012 mm.
Maximum permissible deviation from flatness: 0.1 mm.
Attention! The mating surface for laying the cylinder block after grinding should reduce the height of the cylinder block by no more than -0.2 mm.
Cylinder boring
1. The oversized pistons to be used must be determined based on the largest cylinder bore diameter.
Size increase | Marking |
0.25 mm | 0,25 |
0.50 mm | 0,5 |
0.75 mm | 0,75 |
1.00 mm | 1 |
Attention! Marking is embossed on the bottom of the piston.
2. Measure the outside diameter of the piston.
3. Based on the measured size, determine the bore size. Bore size = Piston diameter 0.02 mm (honing value).
4. Bore each of the cylinders to the estimated size.
Attention! To avoid size variation due to temperature during the honing process, grind the cylinders in the following sequence: #2, #4, #1, and #3.
5. Honed the cylinders to the required design diameter (piston outer diameter clearance).
6. Check up a backlash between the piston and the cylinder.
Attention! When boring, bore all cylinders to one oversize. Do not bore only one cylinder to an oversized size.
Assembly
Install the parts in the following order:
- 1. Crankshaft
- 2. Flywheel
- 3. Piston
- 4. cylinder head
- 5. Toothed belt
- 6. Front cover