Turbocharger - uses the energy of exhaust gases for operation, consists of a single-stage centrifugal compressor and a radial centripetal turbine

The main components of the turbocharger are:

bearing housing, rotor, compressor housing and turbine housing.

The wheels of the turbine and compressor are located at opposite ends of the rotor shaft, cantilevered with respect to the bearings.

The impeller 16 of the centrifugal compressor is of a semi-open type, with radial blades, cast from an aluminum alloy. It is pressed onto the shaft and secured with a nut.

MAZ Turbocharger

The compressor has a bladeless diffuser mounted on compressor housing 17, which is made of aluminum alloy in the form of two semi-volute air collectors.

Compressor housing outlets are adapted to be connected to the engine intake manifold with durite hoses with clamps.

A supply pipe 15 with a protective mesh is attached to the end of the compressor housing. The impeller 3 of the turbine, made of heat-resistant alloy, is connected to the shaft by friction welding.

Turbocharger service

During operation, the turbocharger does not require any adjustments. However, during operation, its operation should be systematically monitored:

  • - according to the pressure gauge, monitor the presence of oil circulation through the turbocharger and the oil pressure in the turbocharger lubrication system;
  • - periodically monitor the operation of the turbocharger by ear immediately after the engine stops;
  • - regularly check the ease of rotation of the turbocharger rotor, for which first unscrew the three nuts, remove the inlet pipe and gasket.

If rotating parts interfere with stationary parts, remove the turbocharger from the engine, disassemble, decarbonize and wash.

Removing the MAZ compressor housing

To detect deviations from normal operation or for post-repair control, you can check the turbocharger on the engine by boost pressure, to do this, unscrew the plug on the left intake manifold and attach a pressure gauge to the hole.

To obtain stable readings, a jet with a hole with a diameter of 0.5 mm must be installed at the inlet to the pressure gauge.

When operating under full load at an engine speed of 2100 min-1, the excess boost pressure should be 0.6 - 0.8 kgf/cm2

When the load is reduced or the speed is reduced, the boost pressure should gradually decrease.

The disassembly and assembly of the turbocharger is carried out in a specially adapted room that provides conditions that exclude contamination of its parts, especially the ingress of sand and dust on rubbing surfaces.

Disassembly should be done in the following sequence:

- disconnect gas, air and oil lines from the turbocharger.

After disconnecting the exhaust line, secure the nozzle ring 2 (see Fig. 1) against falling out with two diametrically located nuts;

  • - unscrew the four bolts securing the bracket to the flywheel housing and remove the turbocharger from the engine together with the bracket;
  • - unscrew the four nuts securing the bracket, remove the bracket and its gasket;
  • - unscrew the three nuts securing the inlet pipe, remove the pipe and gasket;
  • - unscrew the six nuts securing the compressor housing 17, remove the housing assembly with the diffuser;
  • - rotating the rotor 7 by hand, check the ease of its rotation (whether the rotating parts touch the fixed parts).

This check should be done several times in the extreme positions of the rotor, choosing its axial and radial backlashes sequentially in one direction and the other.

If, as a result of this check and inspection of the compressor parts, it is revealed that the cause of rubbing was the compressor parts, disassemble and clean only the compressor, clean, rinse and reassemble the compressor parts.

Before assembly, inspect and, if necessary, replace the rubber sealing ring of the compressor housing;

  • - if, with the removed parts of the compressor, the rubbing of the rotor has not been eliminated, it is necessary to remove the parts of the turbine, to do this, unscrew the six nuts securing its housing 1 and disconnect the turbine housing assembly with the nozzle ring 2;

Checking the ease of rotation of the MAZ turbocharger rotor

  • - check the ease of rotation of the rotor in the bearings with the turbine housing removed. If the rubbing has now disappeared, clean and flush the turbine housing, how to assemble a turbocharger;
  • - if the rubbing has not been eliminated after removing the turbine and compressor housings, you need to remove and clean the rotor in the following order:
  • - unscrew the nut 14 fastening the compressor wheel;

Compressor Wheel Puller

  • - remove the compressor wheel with a special puller (Fig. 4). The location of the nut relative to the wheel and the wheel relative to the shaft are indicated by marks.

If the marks are not preserved, they should be placed before disassembly in such a way that during subsequent assembly the location of these parts relative to each other does not change;

  • - unscrew the two bolts securing the cover 10 of the bearing housing, remove the cover with the sealing ring 21 by screwing the bolts into the threaded holes of the cover;
  • - remove the oil deflector;
  • - unscrew the three screws securing the thrust flange 9, remove the thrust flange and the thrust sleeve from the shaft;
  • - remove the turbocharger rotor towards the turbine;
  • - remove the bearing circlip, remove the washer and bearing sleeve 8, first from one and then from the other side of the bearing housing;
  • - remove the turbine spacer;
  • - remove carbon deposits from the parts with a wooden scraper, after placing them in a bath with kerosene for 3 - 4 hours.
  • With a hair brush - clean the flow parts, rinse all parts with gasoline.

Carefully inspect the turbine and compressor wheels; if there are cracks on the blades or discs, replace the rotor assembly;

  • - if necessary, unscrew the two nuts securing the nozzle ring 2, remove, inspect it and the turbine housing; if there are cracks, replace the parts.

After cleaning or repair, the turbocharger is assembled in reverse order.

Before assembly, all parts of the turbocharger are washed with kerosene and each part is blown with compressed air, bearing bushings and the rotor shaft are lubricated with engine oil.

When assembling the rotor, the marks on the oil deflector and thrust sleeve are aligned with the risk on the shaft.

The compressor wheel is heated to 80 - 100˚s before being pressed onto the shaft.

The compressor wheel nut is tightened until the marks on it and on the compressor wheel are aligned.

All fasteners must be tightened and carefully locked. Thrust flange screws are countersunk.

After assembling the turbocharger, it is necessary to make sure that there is no interference with the rotor when rotating by stationary parts.

When installing a turbocharger on the engine, all lines (gas, air, oil) are connected, after making sure they are clean and free of foreign objects.

Turbocharger maintenance

Maintenance of the turbocharger should be carried out every 3000 hours of engine operation.

Compressor rotor play check

During maintenance, check the axial and radial play of the rotor using an indicator.

The backlash is defined as the difference between the indicator readings when the shaft deviates in two mutually opposite directions (Fig. 5).

Permissible limiting backlash values ​​axial - 0.20 mm, radial - 0.80 mm. If the backlash is greater than the limit values, the turbocharger must be replaced.

Remove deposits from the compressor turbine housing and impellers once a year.

Compressor parts should be cleaned with gasoline, turbine parts - with a calciner.

When installing the turbocharger on the engine, carefully monitor the cleanliness of the pipelines connected to the turbocharger and the absence of objects and debris in them.

After installing the turbocharger, fill the bearing housing with clean oil through the oil inlet.

Carefully monitor the absence of leaks and leaks in air, gas, oil pipelines and their connections.

It should be borne in mind that the optimum operation of the turbocharger is carried out in the range of a higher engine speed.