Troubleshooting and repair of the ZMZ-402 cylinder block of the GAZ-2705 car

Inspect the block, if there are cracks, replace it

Check the tightness of the cooling jacket of the block, to do this, plug all the holes in the block with wooden plugs, except for one, to which the compressed air hose should be connected

Immerse the block in a bath of water and apply compressed air at a pressure of 1.5 atm.

Air bubbles will come out in places of leakage. In the same way, check the tightness of the oil channels of the block.

If a leak is found, the block must be replaced.

Inspect the cylinder liners. If there are scratches, scuffs, shells, etc. on the cylinder mirror, bore the liners to the repair size or replace.

Two repair sleeve sizes are provided. Spare parts are supplied with pistons and piston rings with the same repair dimensions.

It is necessary to bore all the sleeves to the repair size, even if defects are found in only one.

Check clearances between pistons and liners. The nominal gap should be within 0.024–0.048 mm, the maximum allowable gap is 0.25 mm.

To ensure the clearance, the pistons and sleeves are divided by diameter into five size groups A, B, C, D and E.

The letter indicating the sleeve group is applied to the lower centering part of the sleeve. The clearance can be determined by measuring the diameter of the piston and sleeve.

The piston diameter is measured in a plane perpendicular to the piston pin axis and 8.0 mm below the pin axis.

The sleeve diameter is measured in at least three belts within 15–100 mm from the upper edge of the sleeve, in two perpendicular directions.

When replacing liners, new liners are inserted into the cylinder block so that the letter indicating the group of liners is located in the transverse plane.

The sleeve must enter the block completely freely.

Troubleshooting and repair of the ZMZ-402 cylinder block of the GAZ-2705 car

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 liners in the cylinders should be no more than 0.055 mm (this is ensured by selecting the liners in length or by upsetting them with deformation of the copper gasket).

Before removing the sleeves from the block, they must be marked so that during assembly they can be installed in the same place in the same position as they were before disassembly.

When using old liners, remove the unworn band at the top of the liners, flush with the cylinder face.

Check the clearances between the main bearing shells and the crankshaft journals, they should be within 0.02–0.073 mm.