Usually, the head gasket is replaced with the following damage:

  • - Gas breakthrough into the cooling system;
  • - Oil entering the cooling system;
  • - Insufficient compression in one or more cylinders (less than 1 MPa).

Remove

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.

Drain the engine cooling system.

Remove the ignition coils.

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

Disconnect the phase sensor plug from the wiring harness.

Replacing the cylinder head gasket for the ZMZ-405 engine, 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.

Replacing the cylinder head gasket for the ZMZ-405 engine, 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.

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

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

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

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

Replacing the cylinder head gasket for the ZMZ-405 engine, 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.

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

Then pull the accelerator cable upwards out of the bracket.

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.

Replacing the cylinder head gasket for the ZMZ-405 engine, 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.

Disconnect connector 1 from air temperature sensor.

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

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

Disconnect connectors 1 from injectors.

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

Move the wiring harness away from the engine.

Replacing the cylinder head gasket for the ZMZ-405 engine, 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 (described in the article - Replacing the camshafts of the ZMZ-406 engine)

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

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

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

With a “12” hex wrench, we loosen the tightening of ten bolts, after which we unscrew and ...

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

Removing the bolts

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

Removing washers

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

Remove the cylinder head…

Replacing the cylinder head gasket for the ZMZ-405 engine, ZMZ-406

Separate and remove the head gasket

Installation

Install the block head in the reverse order of removal.

Before installation, the adjacent surfaces of the head and block must be cleaned of sealant and gasket residues.

Conduct a general inspection of the cylinder head.

Check with a metal ruler and feeler gauges if the flatness of the surface of the head adjacent to the block is broken.

To do this, put the ruler with an edge on the surface of the head, in the middle along, and then across and measure the gap between the plane of the head and the ruler with feelers.

If the gap exceeds 0.1 mm, the head needs to be replaced.

Replacing the cylinder head gasket for the ZMZ-405 engine, 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 kgf m);
  • - 2nd stage - 130–145 Nm (13.0–14.5 kgf m).