Power Steering System Test (Commercial Chassis)

Important:
^ For proper operation of the power steering system, it is important that the tire pressure be at the required specification. The required specification for this vehicle is 294 kPa (44 psi). If proper tire inflation is not maintained, the power steering pump will go into bypass and possibly fail.
^ The power steering system may be tested using the J 5176-E as described here. It can also be tested with available tool J 25323 Power Steering Analyzer and adapter J 28579 which will measure flow rate as well as pressure.

1. Disconnect pressure hose at pump. Use a small container to catch any fluid which might leak.
2. Connect a spare pressure hose to pump.
3. Connect pressure gage J 5176 to both hoses using adapter J 517~5.
4. Open valve on gage.
5. Start the engine. Allow the system to reach operating temperature, then check the fluid level and add fluid if required.

Important: When the engine is at normal operating temperature, the pressure reading on the gage (valve open) should be in the 552-862 kPa (80-125 psi) range. If the pressure is more than 1380 kPa (200 psi), check the hoses for restrictions and the flow control valve for proper assembly.

6. Fully close the valve three times. (Do not leave the valve fully closed for more than 5 seconds, as the pump could be damaged.) Record the pressure reading each time the valve is closed. Each reading should show at least 10,680 -11,024 kPa (1,550 - 1600 psi). The three readings should be within 173 kPa (25 psi) of each other.
A. If the pressure readings are high enough and are within 173 kPa (25 psi) of each other, the pump is functioning properly.
B. If the pressure readings are high enough, but are not within 173 kPa (25 psi) of each other, the flow control valve in the pump is sticking. Remove the valve; clean it and remove any burrs using crocus cloth or fine hone. If the system appears to be contaminated, flush it. If it is exceptionally dirty, both the pump and the rack and pinion gear must be completely disassembled, cleaned and reassembled.
C. If the pressure readings are less than 10,680 kPa (1,550 psi), replace the pump and recheck.
7. If the pump checks to specification, leave the valve open and turn (or have turned) the steering wheel to both stops. Record the highest pressures and compare with the highest pump pressure recorded. If the pressure at both stops is not the same as the maximum pressure, the rack and pinion is leaking internally and must be disassembled and repaired.
8. Turn off the engine, then remove the testing gage and the spare hose. Reconnect the pressure hose, check the fluid level or make needed repairs.