Component Tests and General Diagnostics
FAULTIf there is a lack of power assistance for the steering the pressure of the hydraulic pump should be checked first before fitting new components to the system. The fault diagnosis chart should also be used to assist in tracing faults in the power steering system. Symptom Related Diagnostic Procedures
Pressure Gauge Connection:
Connecting Pressure Test Gauge
A. Steering box.
B. Steering pump.
C. Existing hose, steering box to pump.
D. Hose JD10-3A.
E. Test adaptor JD10-2.
F. Pressure gauge HY23.
G. Thread adaptor LST10-11.
H. Thread adaptor LST10-11.
CAUTION: Under no circumstances must the steering wheel be held on full lock for more than 30 seconds in any one minute, otherwise there will be a tendency for the oil to overheat and possible damage to the seals may result.
Test Procedure
1. The hydraulic pressure gauge in conjunction with the test adaptor is used for testing the power steering system. This gauge is calibrated to read up to 140 kgf/cm2 (2000 psi) and the normal pressure which may be expected in the power steering system is 77 kgf/cm2 (1100 psi).
2. Under certain fault conditions of the hydraulic pump it is possible to obtain pressures up to 105 kgf/cm (1500 psi). Therefore, it is important to realize that the pressure upon the gauge is in direct proportion to the pressure being exerted upon the steering wheel. When testing, apply pressure to the steering wheel very gradually while carefully observing the pressure gauge.
3. Check, and if necessary replenish, the fluid reservoir.
4. Examine the power steering units and connections for leaks. All leaks must be rectified before attempting to test the system.
5. Check the steering pump drive belt for condition and tension, rectify as necessary.
6. Assemble the test equipment and fit to the vehicle, as shown in the diagram.
7. Open the tap in the adaptor.
8. Bleed the system but exercise extreme care when carrying out this operation so as not to overload the pressure gauge.
9. With the system in good condition, the pressures should be as follows:
(a) Steering wheel held hard on full lock and engine running at 1,000 rev/min, the pressure should be 70 to 77 kgf/cm2 (1000 to 1100 psi).
(b) With the engine idling and the steering wheel held hard on full lock, the pressure should be 28 kgf/cm2 (400 psi) minimum.
NOTE: These checks should be carried out first on one lock, then on the other.
10. Release the steering wheel and allow the engine to idle. The pressure should be below 7 kgf/cm2 (100 psi).
11. If the pressures recorded during the foregoing tests are outside the specified range, or pressure imbalance is recorded, a fault exist in the system. To determine if the fault is in the steering box or the pump, close the adaptor tap for a period not exceeding five seconds.
12. If the gauge fails to register the specified pressure, the pump is at fault and a new unit must be fitted.
13. Repeat the foregoing test after fitting a new pump and bleeding the system. If pump delivery is satisfactory but low pressure or a substantial imbalance exists, the fault must be in the steering box valve and worm assembly.