To check, install the car on a lift or inspection ditch and clean the pressure regulator and protective cover from dirt. Carefully remove the protective cover from the pressure regulator, remove grease residues and clean the torsion-piston connection.
Press the brake pedal with a force of 70-80 kgf and at the same time observe the protruding part of the pressure regulator piston. If the piston moves relative to the pressure regulator housing by 0.5-0.9 mm, while twisting the torsion lever, then the pressure regulator is operational. Continue to press the pedal 2-3 times to fully verify that the pressure regulator is working. If the piston remains stationary when the pedal is depressed, indicating corrosion between the piston and housing 4 (see fig. 140), the pressure regulator is replaced with a new one.
After making sure that the pressure regulator is working and that there is no fluid leakage between the piston and the regulator housing, apply a layer of DT-1 grease on the axis and protruding part of the piston and, putting 5-6 g of this grease in a rubber boot, install it in place.