Fault-Tracing The Power Steering System
Fault-tracing the power steering system
Special tools:
999 5175 NIPPLE 999 5175 Nipple
999 5319 CLUTCH 999 5319 Clutch
999 5055 Pressure gauge 999 5055 Pressure Gauge
General
Preparations which must be carried out before reading off the pump pressure:
- Check the level and condition of the oil. Top up or replace the oil if necessary. Bleed the system if necessary. See Removing and/or installing the power steering pump, gasoline powered cars
- Check the tension of the V-belt. Check the condition of the V-belt
- Check the mounting for the power steering pump.
Connect the test instrument
Place paper over the generator (GEN) as protection against the oil.
Connect instrument 999 5055 Pressure gauge 999 5055 Pressure Gauge between the pump and the pressure hose from the steering gear housing.
Use nipples 999 5175 NIPPLE 999 5175 Nipple and 999 5319 CLUTCH 999 5319 Clutch.
Align nipple 999 5175 NIPPLE 999 5175 Nipple with the pipe screws and washers from nipple 999 5319 CLUTCH 999 5319 Clutch.
Torque:The maximum torque for the pipe screws is 25 Nm.
Note! Do not tighten harder.
Note! If the nipple cannot be installed, turn the hose clamp from the main hose.
Note! Connect the pipe from the instrument cock to the pressure pipe for the steering gear. The cock should be parallel with the hose.
Start the engine
Install the fluid reservoir. Tighten by hand only.
Bleed the system. See Removing and/or installing the power steering pump, gasoline powered cars .
Wait until the oil and power steering pump have reached operating temperature
Note! Pressure testing only provides accurate results only when the oil has reached an operating temperature of approximately 80°C.
Test
Note! After connecting the test equipment, always bleed the power steering system. See Removing and/or installing the power steering pump, gasoline powered cars .
Checking the low pressure
Manometer pressure
A. (Saginaw) Below 1000 kPa, see Checking the high pressure.
B. (ZF) Above 1000 kPa, see Check the high-pressure hose.
Note! Carry out test pressurization twice by switching the engine off and on. The pressure must be stable and must not fluctuate.
Check the high-pressure hose
Check the high-pressure hose for blockage and leakage. Clean and replace the high-pressure hose if necessary.
Repeat the check from step Start the engine.
Checking the high pressure
Close the intake cock on the manometer. Keep the cock closed for 3 seconds.
Read off and note the measurement results.
Repeat the check twice.
Note! The outlet cock must not be closed for longer than 10 seconds. This is to prevent damage to the power steering pump.
- Pressure = Nominal, pressure variations within 3.5 MPa (35 bar), the system is OK.
Pressure check completed.
Install the high pressure hose on the power steering pump. Bleed the pump. See stage Removing and/or installing the power steering pump, gasoline powered cars and Removing and/or installing the power steering pump, gasoline powered cars
- Pressure above nominal, the pressure variations are not within 3.5 MPa (35 bar)
- Pressure below nominal, pressure variation within 3.5 MPa (35 bar). See step Install the control valve.
Note! Nominal pressure in the high pressure check is 9.6 MPa (98 bar Saginaw), 11.0 MPa (110 bar ZF).
Install the control valve
Note! Replace the power steering pump if the read off values do not correspond with the specified values even after repeated diagnostic testing. See Removing and/or installing the power steering pump, gasoline powered cars .