Troubleshooting and repair of the cylinder block ZMZ-405 GAZ-2705

To determine the technical condition and repair of the cylinder block, remove the engine from the car and disassemble it

Remove the cylinder head (see "Replacing the cylinder head gasket"), the crankshaft (see "Removing, repairing and installing the crankshaft"), the connecting rod and piston group (see "Removing, repairing and installing the connecting rod piston group"), oil crankcase and oil pump (see "Removal, repair and installation of the 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 unit.

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.

Pistons and piston rings of the corresponding repair sizes are supplied as spare parts.

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 letter indicating the cylinder group is painted on the left outer side of the block opposite each cylinder.

The clearance can be determined by measuring the diameters of the piston and cylinder. The piston diameter is measured in a plane perpendicular to the piston pin axis at a distance of 8.0 mm below the piston pin axis. the diameter of the cylinder is measured in at least three belts within 15-100 mm from the upper surface of the block (in two mutually perpendicular directions).

We also look at the article - "Repair of the ZMZ-405 cylinder block"