TM 5-2420-230-24-1
NOTE:
All tests must be performed with the vehicle parked on a clean, dry, solid surface, with
the engine running and the full weight of the vehicle on the front wheels.
1.
Connect the pressure and flow tester in series with the pressure line of the pump.
2.
Start the engine and check system oil level. Make sure the oil flow is in the proper direction as indicated
by the arrow on the flow meter.
3.
Place a thermometer in the reservoir.
4.
Run the engine at idle speed. Slowly close the shutoff valve until you have a pressure reading of 1000
PSI. Maintain this pressure until system temperature reaches 150 degrees Fahrenheit. Open the shutoff
valve all the way when the temperature is 150 degrees.
5.
Check System Back Pressure:
Normal system back pressure will be between 0 and 100 PSI with the engine idling and the steering wheel
stationary. Dual systems will normally read slightly higher. Back pressure should be checked at normal
operating temperature.
6.
Pump Maximum Relief Pressure:
With the engine running at specified idle speed, slowly turn the shutoff valve until it's closed and read the
pressure at which the pressure relief valve opens. (Open the shutoff valve as quickly as possible to avoid
heat build-up or possible damage to the steering pump.) This pressure reading should equal the maximum
pump pressure specified by the vehicle manufacturer. Check specifications.
WARNING
A BAD PRESSURE RELIEF VALVE MAY NOT RELIEVE PUMP PRESSURE.
CLOSING THE SHUTOFF VALVE MAY CAUSE SEVERE PUMP DAMAGE OR
HIGH-PRESSURE HOSES TO RUPTURE. WATCH THE PRESSURE GAUGE
CLOSELY. IF PRESSURE RISES RAPIDLY OR GOES ABOVE 2500 PSI. STOP!
DO NOT CLOSE THE VALVE ALL THE WAY.
SOME STEERING PUMPS ARE NOT EQUIPPED WITH INTEGRAL RELIEF
VALVES. CLOSE THE SHUTOFF VALVE SLOWLY AND WATCH THE
PRESSURE. IF SYSTEM PRESSURE GOES ABOVE 2500 PSI DO NOT
CONTINUE TO CLOSE THE SHUTOFF VALVE. PUMP DAMAGE OR PERSONAL
INJURY MAY RESULT.
7.
Flow Test:
Measure oil flow under the following conditions. Record your findings on the Troubleshooting Check-
list in this section.
Flow at idle with back pressure only
Flow at idle under a 1500 PSI load applied with the shutoff valve
Flow at full governed RPM with back pressure only
Flow at full governed RPM under a 1500 PSI load applied with the shutoff valve
8.
Aerated Oil:
Visually check for air mixed with the oil in the steering system. The oil should be clear. Any signs of frothing
indicates air in the system and steering performance will be affected. Carefully check for leakage on the suction
side of the steering pump. Drain, refill, and bleed the system. Follow the procedure for setting relief plungers
in the "Common Procedures" section of this manual.
Before any steering gear repairs are made, complete the hydraulic supply evaluation and make any
repairs. Many times steering gears have been repaired or replaced needlessly because a hydraulic supply
system evaluation has not been made.
Additional references to pressure and flow testing will be made in the diagnosis charts in the "General
Diagnosis" section of this manual.
9.
Dry Park Pressure and Input Effort:
Measure and record the pressure required to steer the vehicle from full left to full right while parked. Input
effort is measured at the steering wheel retaining nut. Use a dial type inch pound torque wrench to check
dry park steering.
K-19
