Hydraulic Pressure in P/S Circuit Check

Hydraulic Pressure in P/S Circuit Check

1) After cleaning joint of high pressure hose and P/S pump thoroughly, disconnect hose from pump and install special tool (oil pressure gauge, attachment and hose).
Special Tool

(A): 09915-77412

(B): 09915-77420









2) Check each connection for fluid leakage and bleed air. Refer to Service and Repair P/S System Air Bleeding Procedure.
3) With engine idling, turn steering wheel and warm up engine till temperature of fluid in tank rises to 50 - 60 °C (122 - 140 °F).





4) Check back pressure by measuring hydraulic pressure with engine idling and hands off steering wheel.

When back pressure is higher than specified values, check control valve and piping for clogging.

Back pressure
Lower than 1000 kPa (10.2 kgf/cm2, 145 psi)









5) Check relief pressure.
a) Increase engine speed to about 600 r/min. (rpm). Close gauge valve gradually while watching pressure increase indicated by gauge and take reading of relief pressure (maximum hydraulic pressure).
If it is higher than specified values, possible cause is malfunction of relief valve.
If it is lower than specified values, possible cause is either failure of P/S pump or settling of relief valve spring.

Relief pressure when gauge value is closed
7150 - 7850 kPa (72.9 - 80.0 kgf/cm2, 1037 - 1138 psi)

NOTE:
If the gauge valve is kept closed for too long, the P/S pump will be damaged.

Do not close the gauge valve for more than 10 seconds.









b) Open gauge valve fully and increase engine speed to about 1500 r/min. (rpm). Then turn steering wheel to the left or right fully and take reading of relief pressure.
If it is higher than specified values, possible cause is malfunction of relief valve.
If it is lower than specified values, possible cause is failure in steering gear case. Replace gear case.

Relief pressure when gauge value is opened
7150 - 7850 kPa (72.9 - 80.0 kgf/cm2, 1037 - 1138 psi)

NOTE:
If the steering wheel is held at the fully turned position for too long, the P/S pump will be damaged.

Do not hold the steering wheel at the fully turned position for more than 10 seconds.