Power Steering Pressure Test
A power steering pressure test checks the system's fluid pressure, testing the high-pressure lines, power steering pump, control valve, and the pressure relief valve. Check for external leaks and top fluid levels before beginning this test. Review manufacturer's specifications and procedures before preceding, and listen for any strange noises while the valve is opened and closed.
1. With the engine stopped, install the pressure gauge with the shutoff valve in the open position. Place a thermometer in the reservoir.
2. Start and idle the engine with the valve in the open position. Turn the steering wheel left and right several times to release any air bubbles and bring the fluid to operating temperature.
3. With the gauge connected, close the shutoff valve for 5 seconds and compare it with the manufacturer's specifications. Never hold this valve closed for more than 5 seconds unless instructed to do so by the manufacturer of the pump. This will cause the fluid to overheat, possibly damaging the power steering pump. If the reading is not within specifications, the power steering pump is weak and must be replaced.
4. With the shutoff valve in the open position, check the gear housing for leaks by holding the steering wheel against its stop and checking fluid pressure against specifications. Do not hold the wheel in this position for too long. Power steering systems reach pressures above 1000 lbs per square inch. If the pressure is too low, the internal gear housing may have an internal leak, undetectable during a visual inspection.
5. Check the flow control valve's operation with the shutoff valve in the open position and record the reading at 1000 RPM and 3000 RPM. Compare these two readings against specifications. If these two readings are not within specifications, the flow control valve is faulty and must be replaced.