Before assembly, it is necessary to design the cylinder block and determine its further operation
Disassembly of the engine was discussed in the article – «How to disassemble the ZMZ-402 engine»
The crankshaft defect was considered in the article – «Dismantling and troubleshooting of the crankshaft ZMZ-402»
Repair of the connecting rod-piston group was discussed in the article – «Repair of the connecting rod-piston group ZMZ-402».
1. Inspect the unit, if there are cracks — replace it.
2. Check the tightness of the cooling jacket of the unit, to do this, plug all the holes in the block with wooden plugs, except for one, to which a compressed air hose is connected.
Lower the unit into a bath of water and apply compressed air at a pressure of 1.5 atm.
In places of leakage, air bubbles will come out.
In the same way, check the tightness of the oil channels of the unit.
If a leak is detected, the unit must be replaced.
3. Inspect the cylinder liners.
If there are scratches, bullies, sinks, etc. on the cylinder mirror, waste the sleeves for the repair size or replace.
There are two repair sizes of sleeves specified in the table.
Pistons and piston rings with the same repair dimensions are supplied to spare parts. Under the repair size, it is necessary to drill all the sleeves, even if defects are found only in one.
4. Check the gaps between the pistons and the sleeves. The nominal clearance should be within 0.024–0.048 mm, the maximum permissible -0.25 mm.
To ensure the size of the gap, the pistons and sleeves are divided by diameter into five dimensional groups A, B, C, D and D. The letter denoting the sleeve group is applied to the lower centering part of the sleeve.
The gap can be determined by measuring the diameter of the piston and sleeve.
The diameter of the piston is measured in a plane perpendicular to the axis of the piston pin, and 8.0 mm below the axis of the finger.
The diameter of the sleeve is measured in at least three belts within 15-100 mm from the upper edge of the sleeve, in two perpendicular directions.
5. When replacing the sleeves, new sleeves are inserted into the cylinder block so that the letter denoting the sleeve group is located in the transverse plane.
The sleeve must enter the unit completely freely.
The sleeve installed with a copper gasket in the block should protrude 0.02-0.1 mm above the surface of the block.
The difference in the protrusion of the sleeves along the cylinders should be no more than 0.055 mm (this is ensured by the selection of the sleeves along the length or by their settling with deformation of the copper gasket).
Before removing the sleeves from the block, they must be marked so that during assembly they are installed in the same place in the same position as they were before disassembly.
When using old sleeves, you need to remove the unworn belt at the top of the sleeve, flush with the cylinder mirror.
6. Check the gaps between the liners of the main bearings and the crankshaft necks, they should be within 0.02-0.073 mm.
The clearances can be calculated by measuring the diameters of the crankshaft necks and neck holes with the inserts and caps of the main bearings installed, or measure them using calibrated plastic wire. The gaps are measured in the following order:
a). Clean the crankshaft necks and bearing liners.
b). Lay the crankshaft on the bed of the main bearings with the installed inserts.
c). Put cuttings of calibrated plastic wire on the crankshaft necks.
d). Install the covers of the main bearings with the inserts installed in them
e). Wrap the bolts securing the covers and tighten with a torque of 100 N · m (10 kgf * m). At the same time, it is forbidden to turn the crankshaft.
f). Remove the caps of the main bearings and determine the gap by flattening the wire on the scale printed on the wire packaging
Dimensional groups of cylinders and pistons
Group A:
- Cylinder diameter, nominal size 92.036 - 92.024 mm
- Piston diameter, nominal size 92,000 - 91.988 mm
- Cylinder diameter 1st repair size * 92.536 - 92.524 mm
- Piston diameter 1st repair size 92,500 - 92.488 mm
- Cylinder diameter 2nd repair size ** 93,036 – 93,024 mm
- Piston diameter 2nd repair size 93,000 - 92.988 mm
Group Б:
- Cylinder diameter, nominal size 92.048 - 92.036 mm
- Piston diameter, nominal size 92.012 - 92,000 mm
- Cylinder diameter, 1st repair size 92.548 - 92.536 mm
- Piston diameter, 1st repair size 92.512 - 92,500 mm
- Cylinder diameter, 2nd repair size 93.048 - 93.036 mm
- Piston diameter 2nd repair size 93,012 - 92,000 mm
Group В:
- Cylinder diameter, nominal size 92.060 - 92.048 mm
- Piston diameter nominal size 92.024 - 92.012 mm
- Cylinder diameter, 1st repair size 92.560 - 92.548 mm
- Piston diameter 1st repair size 92.524 - 92.512 mm
- Cylinder diameter, 2nd repair size 93.060 - 93.048 mm
- Piston diameter 2nd repair size 93.024 - 92.012 mm
Group G:
- Cylinder diameter, nominal size 92.072 - 92.060 mm
- Piston diameter nominal size 92.036 - 92.024 mm
- Cylinder diameter, 1st repair size 92.572 - 92.560 mm
- Piston diameter 1st repair size 92.536 - 92.524 mm
- Cylinder diameter, 2nd repair size 93.072 - 93.060 mm
- Piston diameter 2nd repair size 93.036 - 92.024 mm
Group D:
- Cylinder diameter, nominal size 92.084 - 92.072 mm
- Piston diameter nominal size 92.048 - 92.036 mm
- Cylinder diameter, 1st repair size 92.584 - 92.572 mm
- Piston diameter 1st repair size 92.548 - 92.536 mm
- Cylinder diameter, 2nd repair size 93.084 - 93.072 mm
- Piston diameter 2nd repair size 93.048 - 92.036 mm
* 1st repair size increased by 0.5 mm
** 2nd repair size increased by 1.0 mm
