Replacing the cylinder head gasket ZMZ-406

The cylinder head gasket is replaced if it is damaged

The main signs of damage to the head gasket:

  • - insufficient compression - below 1 MPa (10 kgf/cm 2) in one or more cylinders;
  • - breakthrough of gases into the cooling system (seething, foaming of liquid in the radiator, rapid drop in the liquid level in the expansion tank in the absence of external leaks);
  • - ingress of coolant into the lubrication system (emulsion on the oil level indicator, separation of oil drained from the crankcase, especially noticeable in a transparent container);
  • - oil ingress into the cooling system (oil film on the surface of the liquid in the expansion tank).


The head of the block can be removed with the receiver and exhaust manifold.

If the head of the block is removed from the engine installed on the car, you must first perform the following operations:

Disconnect the fuel supply and return lines.

Remove the battery.

Remove the hood.

Cylinder head gasket ZMZ-406

Remove the six bolts 1 and remove the front mudguard 2 of the engine.

Drain the engine cooling system.

Remove the ignition coils.

Cylinder head gasket ZMZ-406

Disconnect the phase sensor plug from the wiring harness.

Cylinder head gasket ZMZ-406

Unscrew the screws and disconnect the wires from the sensors for oil pressure indicator 1 and emergency oil pressure 2.

Disconnect plug connectors from engine temperature sensors 5, coolant temperature indicator 4, coolant overheat indicator 3.

Loosen the clamp and remove the hose to the expansion tank from fitting 6 of the thermostat.

Cylinder head gasket ZMZ-406

Loosen clamp 1 and remove hose 2 from the fitting to the non-return valve of the brake booster.

Disconnect connector 3 from throttle position sensor.

Cylinder head gasket ZMZ-406

Unscrew nut 1 and remove the blue ground wire from the stud at the front end of the receiver.

Unscrew nut 4 and pull accelerator cable 3 out of the air throttle actuator sector.

Disconnect plug 2 from the wiring harness, located between the engine intake pipes, the speed and crankshaft timing sensor, installed near the crankshaft pulley ring gear.

Cylinder head gasket ZMZ-406

Slide the cable gland 3 from the threaded lug 2 of the cable sheath, unscrew the nut 1 securing the cable lug and pull the lug 2 out of the bracket fixed to the engine intake pipe by sliding it back.

Then pull the accelerator cable upwards out of the bracket.

Cylinder head gasket ZMZ-406

Pull back the accelerator cable holder and remove the cable from it.

Move the accelerator cable away from the engine.

Disconnect the wires from the generator.

Cylinder head gasket ZMZ-406

Disconnect connector 1 from the idle speed controller.

Unscrew nut 2 and remove the ground wires from the stud at the rear end of the receiver.

Cylinder head gasket ZMZ-406

Disconnect connector 1 from the air temperature sensor.

Loosen clamp 2 and remove the coolant supply hose from the heater tap fitting

Disconnect connectors 1 from injectors.

Unbend the holders 2 of the wiring harness and remove the harness from the holders.

Move the wiring harness away from the engine.

Cylinder head gasket ZMZ-406

Then, disconnect the muffler intake pipe from the exhaust manifold, disconnect the hose from the throttle body, remove the radiator supply pipe, remove the generator.

Further, the procedure for removing the head of the block from the engine removed from the car and from the one installed on the car is the same.

Remove the camshafts.

Cylinder head gasket ZMZ-406

Loosen clamps 1 and remove hoses 2 and 3 from throttle body fittings.

Remove thermostat with housing.

Remove the spark plugs.

Cylinder head gasket ZMZ-406

Remove the bolts 1 securing the block head. Remove screws 1 and washers.

Remove the cylinder head and head gasket.

Do not drive a screwdriver or any other tool between the cylinder head and the cylinder block, as this may damage the surface of the cylinder head adjacent to the cylinder block.


Install the block head in the reverse order of removal.

Cylinder head gasket ZMZ-406

The order of tightening the block head bolts is shown in the figure.

Tighten the block head bolts in two steps:

  • - 1st stage - 40–60 Nm (4.0–6.0 kgcm);
  • - 2nd stage - 130-145 Nm (13.0-14.5 kgcm).


Maintenance of the K-126GU carburetor (for engines mod. 4178) The K-126GU carburetor is used to complete the 4178 model engines, as an option to replace the K-151V carburetor

Repair of the crankshaft consists of regrinding the main and connecting rod journals to the next repair size