Oil Pump Pressure Test
OIL PUMP PRESSURE TESTRequired Special Tools:
^ MB990662: Power Steering Oil Pressure Gauge
^ MB991548: Oil Pressure Gauge Adapter A (Pump Side)
^ MB991549: Oil Pressure Gauge Adapter B (Hose Side)
1. Disconnect the pressure hose from the oil pump, and then connect the special tools MB991548, MB990662 and MB991549.
2. Bleed air, then turn the steering wheel several times while the vehicle is not moving so that the temperature of the fluid rises to approximately 50 - 60°C (122 - 140°F).
3. Start the engine and idle it at 700 ± 50 r/min.
CAUTION
The pressure gauge shut-off valve must not remain closed for more than 10 seconds.
4. Fully close the shut-off valve of the pressure gauge and measure the oil pump relief pressure to confirm that it is within the standard value range. Open it again immediately after checking the pressure.
Standard value: 8.1 - 8.8 MPa (1,175 - 1,276 psi)
5. If it is not within the standard value, replace the oil pump.
6. Check whether or not the hydraulic pressure is the standard value when no-load conditions are created by fully opening the shut-off valve of the pressure gauge.
Standard value: 1.0 MPa (145 psi)
7. If it is not within the standard value, the probable cause is a malfunction of the oil line or steering gear, so check these parts and repair as necessary.
8. Turn the steering wheel all the way to the left or right; then check whether or not the retention hydraulic pressure is the standard value.
Standard value: 8.1 - 8.8 MPa (1,175 - 1,276 psi)
9. If not the standard value, overhaul the steering gear. Remeasure fluid pressure.
10. Remove the special tools MB991548, MB990662 and MB991549, and then tighten the pressure hose to the specified torque.
Tightening torque: 57 ± 7 Nm (42 ± 5 ft-lb)
11. Bleed the system.