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

Conventionally, all operations take place on the removed engine.

Removing the coolant pump from the engine

To remove the pump, you need to loosen and remove the pump drive belt.

Ремонт насоса охлаждающей жидкости ЗМЗ-402Ремонт насоса охлаждающей жидкости ЗМЗ-402

Holding the pump pulley with the "gas" wrench, with the "12" key, unscrew the four bolts securing the pulley.

You can also hold the pulley with a spudger, pushing it into the spacer between the two bolts.

Remove the pulley and plate

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

Ремонт насоса охлаждающей жидкости ЗМЗ-402Ремонт насоса охлаждающей жидкости ЗМЗ-402

Using the "13" head, unscrew the five nuts securing the pump to the cylinder block.

Remove the coolant pump

Ремонт насоса охлаждающей жидкости ЗМЗ-402Ремонт насоса охлаждающей жидкости ЗМЗ-402

Remove the gasket by carefully prying it with a knife

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

Ремонт насоса охлаждающей жидкости ЗМЗ-402Ремонт насоса охлаждающей жидкости ЗМЗ-402

Tap gently with a copper hammer to remove the pump cover

Removing the gasket

Dismantling the coolant pump

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

Ремонт насоса охлаждающей жидкости ЗМЗ-402Ремонт насоса охлаждающей жидкости ЗМЗ-402

Remove impeller 1 of the pump with a puller. The impeller is molded from plastic, but has a metal hub, in which a thread is cut for a puller.

Press the hub 1 of the pump pulley with a puller. Unscrew the bearing retainer 2 and press out the bearing with the pump shaft towards the pulley

Ремонт насоса охлаждающей жидкости ЗМЗ-402

Press out the oil seal 1 of the pump

Rinse and remove deposits from the pump parts

Troubleshooting the coolant pump

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

If a large backlash is felt in the bearing, traces of grease leakage from under the protective rings or rolling of the balls when rotating the bearing are noticeable, it must be replaced as an assembly with a roller.

2. Inspect the impeller. If it has cracks, chips, etc., replace it.

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

Assembling the pump

Ремонт насоса охлаждающей жидкости ЗМЗ-402

The pump is assembled in the reverse order of disassembly. When assembling the pump, inspect the gaskets; if there are tears on them or the gaskets are heavily compressed, they must be replaced.

When pressing in the impeller and hub, the stop must be on the pump shaft.

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

After screwing in the bearing retainer, the edges of the hole must be bored so that part of the metal enters the slot of the retainer to prevent self-unscrewing.

Installation is carried out in the reverse order of removal.

Tightening torques of parts:

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

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