Disassembly and inspection of the pump

Before disassembly, the pump must be removed from the car, after draining the oil from the pump and cleaning and rinsing its outer surface

To disassemble and check the pump:

Remove tank cap and filters.

Remove the tank by unscrewing the four bolts.

Install the pump so that its shaft is vertical and the pulley is at the bottom, and remove the pump cover by unscrewing the four bolts.

When removing the cover, keep the valve from falling out

Mark the position of the distribution disc relative to the stator and remove it from the pins.

Mark the position of the stator relative to the pump housing and remove the stator (the arrow on the stator indicates the direction of rotation of the pump shaft).

Remove the rotor together with the blades.

The stator, rotor and pump blades are selected individually at the factory, so their completeness must not be violated during disassembly. You can't swap blades either.

When replacing the stator, rotor and blades, install them only as a set

In case of emergency, remove the pulley, retaining ring and pump shaft along with the front bearing.

ZIL-131 power steering pump

If there is a large bearing (see Fig. 1, b), remove it only if necessary, since the seal may be damaged and it will need to be replaced.

When installing a new bearing and seal, take care not to damage the lips of the seal.

Check that the relief valve in the pump cover moves freely and is not nicked or worn.

The valve and the pump cover are selected individually at the factory, so their completeness must not be violated during disassembly

If necessary, clean the nicks or replace the parts as a set.

Check the tightness of the seat 16 (Fig. 1) of the safety valve and, if necessary, tighten it.

Check for dirt in all channels of the pump parts and clean the channels.

Check for scoring or wear on the end surfaces of the rotor, housing and distribution disc.

In case of minor scuffing or wear, grind these surfaces on the plate, then rinse the parts thoroughly.

Check if the blades move freely in the grooves of the rotor and if they are worn excessively.

Pump Assembly

  • 1. We assemble in the reverse order.
  • 2. Install the vaned stator-rotor and distribution disc in accordance with the marks made during disassembly and the arrow indicating the direction of rotation. In this case, the chamfer of the slotted hole must face the pump housing.
  • 3. Install the bypass valve cover. The hexagon of the valve seat must face the inside of the hole.
  • 4. The tightening torque of the M6 ​​bolts securing the tank should be 0.6-0.8 kgm.
  • 5. The tightening torque of the nut securing the pump pulley should be 5.0-6.5 kgm.
  • 6. The pump shaft must rotate freely, without jamming.

Checking the pressure developed by the pump

The check must be carried out by installing a special device between the pump and the high-pressure hose (Fig. 2), which has a pressure gauge with a scale of up to 80 kg / cm2 and a valve that closes the oil supply to the hydraulic booster. p>

Checking the pressure of the ZIL-131 hydraulic pump

To check, open the valve and turn the wheels all the way; the oil pressure at low idle must be at least 60 kg/cm2.

If the oil pressure is less than 60 kg/cm2, then slowly close the valve, watching the increase in pressure on the pressure gauge.

With a working pump, the pressure should rise and be at least 65 kg/cm2.

In this case, the fault must be sought in the steering mechanism. If the pressure does not increase, then the pump is faulty.

If the pressure with the valve closed is greater than the pressure that was with the valve open, but below 60 kg/cm2 , then both units are faulty.

When checking, it is impossible to keep the valve closed for more than 15 seconds, and the wheels turned all the way.

The check should be carried out at an oil temperature in the tank of 65-75 ° C.

If necessary, the oil can be heated by turning the wheels from lock to lock, holding them against the stops each time for no more than 15 seconds.