Troubleshooting and repair of the ZMZ-406 cylinder block
To determine the technical condition and repair of the cylinder block, remove the engine from the car and disassemble it
Remove the cylinder head, crankshaft, connecting rod and piston group, oil sump and oil pump, as well as all attachments
Inspect the cylinder block. If cracks are found, replace it.
Check the tightness of the cooling jacket of the block by pressing: plug all the holes in the block with wooden plugs, except for the one to which the compressed air supply hose is connected (You can also use rubber and plastic plugs of a suitable size).
Immerse the unit in a bath of water and apply compressed air at a pressure of 1.5 atm.
Air bubbles will come out in places with broken tightness. If a leak is found, replace the block.
In the same way, check the tightness of the oil channels of the block.
Inspect the cylinders.
If there are scuffs and other defects on the cylinder mirror, bore the cylinders to the repair size and honing.
There are two overhaul cylinder sizes shown in the table.
Pistons and piston rings of the corresponding repair sizes are supplied as spare parts.
Note:
All cylinders must be bored to the repair size, even if defects are found in only one.
Check the clearances between the cylinders and pistons.
The nominal gap is 0.024-0.048 mm, the maximum allowable gap is 0.25 mm.
Cylinders and pistons are divided by diameter into five size groups: A, B, C, D, e.
The cylinder group letter is inked on the left outer side of the block opposite each cylinder.
The clearance can be determined by measuring the piston and cylinder diameters.
The piston diameter is measured in a plane perpendicular to the piston pin axis, 8.0 mm below the piston pin axis.
The cylinder diameter is measured in at least three belts within 15-100 mm from the upper surface of the block (in two mutually perpendicular directions).
|
Cylinder and piston dimension groups |
||
|---|---|---|
|
Group |
Cylinder diameter, mm |
Piston diameter, mm |
|
A |
nominal size 92.036 – 92.024 |
nominal size 92,000 – 91,988 |
|
1st repair size * 92.536 – 92.524 |
1st repair size 92,500 – 92,488 |
|
|
2nd repair size ** 93.036 – 93.024 |
2nd repair size 93,000 – 92,988 |
|
|
Б |
nominal size 92.048 – 92.036 |
nominal size 92,012 – 92,000 |
|
1st repair size 92,548 – 92,536 |
1st repair size 92,512 – 92,500 |
|
|
2nd repair size 93.048 – 93.036 |
2nd repair size 93,012 – 92,000 |
|
|
В |
nominal size 92.060 – 92.048 |
nominal size 92.024 – 92.012 |
|
1st repair size 92,560 – 92,548 |
1st repair size 92.524 – 92.512 |
|
|
2nd repair size 93,060 – 93,048 |
2nd repair size 93.024 – 92.012 |
|
|
Г |
nominal size 92.072 – 92.060 |
nominal size 92.036 – 92.024 |
|
1st repair size 92.572 – 92.560 |
1st repair size 92.536 – 92.524 |
|
|
2nd repair size 93.072 – 93.060 |
2nd repair size 93.036 – 92.024 |
|
|
Д |
nominal size 92.084 – 92.072 |
nominal size 92.048 – 92.036 |
|
1st repair size 92.584 – 92.572 |
1st repair size 92,548 – 92,536 |
|
|
2nd repair size 93.084 – 93.072 |
2nd repair size 93.048 – 92.036 |
|
|
* 1st repair size increased by 0.5 mm ** 2nd repair size increased by 1.0 mm |
||
Check the clearances between the main bearing shells and the crankshaft journals. The gap should be within 0.019–0.073 mm.
Clearances can be calculated by measuring the diameters of the crankshaft journals and journal holes with the main bearing shells and caps installed, or by measuring them with a calibrated plastic wire.
Measure the gaps in the following order:
Clean the crankshaft journals and bearing shells.
Place the crankshaft on the bed of the main bearings with the liners installed.
Place pieces of calibrated plastic wire on the crankshaft journals.
Install the main bearing caps with the liners installed in them, tighten the cap bolts and tighten to 100 Nm (10 kgfm). In this case, it is forbidden to turn the crankshaft.
Remove the main bearing caps and determine the gap by the flattening of the wire according to the scale printed on the wire package.