Usually, the coolant pump is removed from the engine due to noise during its operation, excessive radial play of the pump shaft

Conditionally, all operations are carried out on a removed engine.

Removing the coolant pump from the engine

To remove the pump, loosen and remove the pump drive belt.

Repair of ZMZ-402 coolant pump

Holding the pump pulley with a “gas” key, with a “12” key, unscrew the four bolts securing the pulley.

You can still hold the pulley with a mounting spatula, inserting it into the gap between the two bolts.

Repair of ZMZ-402 coolant pump

Remove the pulley and plate

If a fan is attached to the pump hub, then unscrew the bolts, holding the fan blades.

Repair of ZMZ-402 coolant pump

Using the “13” head, we unscrew the five nuts securing the pump to the cylinder block.

Repair of ZMZ-402 coolant pump

Remove the coolant pump

Repair of ZMZ-402 coolant pump

Remove the gasket by carefully prying it with a knife

Repair of the ZMZ-402 coolant pump

Using a key or a “10” head, unscrew the bolt securing the pump cover

Repair of ZMZ-402 coolant pump

Carefully tapping with a copper hammer, remove the pump cover

Repair of ZMZ-402 coolant pump

Remove the gasket

Disassembly of the coolant pump

For motor pump mod. 402, you must first unscrew the two bolts and remove the pump cover with gasket.

Cooling pump impeller

Remove pump impeller 1 using a puller.

1 - pump pulley hub, 2 - bearing retainer

The impeller is molded from plastic, but has a metal hub, in which a thread for a puller is cut.

Compress the hub 1 of the pump pulley with a puller.

Unscrew retainer 2 of the bearing and press the bearing with the pump shaft towards the pulley

Pushing out the coolant pump shaft seal

Push out seal 1 pump

Rinse and clean the pump parts from deposits

Coolant pump troubleshooting

The bearing on the pump shaft must rotate freely without binding, otherwise replace the bearing with shaft assembly.

If a large play is felt in the bearing, traces of lubricant leakage from under the protective rings are noticeable or the balls roll when the bearing rotates, it must be replaced as an assembly with the roller.

Inspect the impeller.

If it has cracks, chips, etc., replace it.

Inspect the gland.

If it has tears, cracks, the rubber has lost its elasticity, the compression spring is broken, replace the oil seal.

Pump Assembly

Pressing on the pulley hub and water pump impeller: A = (117.5 ± 0.2) mm (models 402 and 4021); B = 0 / 0.2 mm (engines model 402 and 4021); C = 0.9/1.3 mm (Model 4062 motors)

The pump is assembled in the reverse order of disassembly.

When assembling the pump, inspect the gaskets, if they have tears or the gaskets are heavily compressed, they must be replaced.

When pressing the impeller and hub, the emphasis should be on the pump shaft.

When assembling the pump, keep the dimensions shown in the figure.

After screwing in the bearing retainer, you need to punch out the edges of the hole so that part of the metal enters the slot of the retainer to prevent self-loosening.

Installation is carried out in the reverse order of removal.

Tightening torques for parts:

  • Water pump pulley bolts 22-27 Nm (2.2-2.7 kgf.m)
  • Water pump mounting bolts 22-27 Nm (2.2-2.7 kgf.m)