Power Steering Pressure Test
A power steering pressure test checks the fluid pressure created by the power steering pump, control valve, and the pressure relief valve. Always get the manufacturers specifications and procedures before performing a power steering pump pressure test. Check the fluid levels, belt tension, external leaks, and make sure the tire pressures are correct.
A vehicle with low power steering pump pressure will require increased steering effort to steer. Sometimes the pressure may be erratic causing the wheel to jerk while turning the vehicle. Listen for any abnormal noises while turning the wheel. A squeal may be something as simple as a loose belt or weak belt tensioner.
1. With the engine stopped install the pressure gauge with the shutoff valve in the open position.
2. Start and idle the engine with the valve in the open position. Turn the wheel left and right several times to release any air bubbles and bring the fluid to normal operating temperature.
3. With the gauge connected close the shutoff valve for 5 seconds and check against manufacturers specifications. Never hold this valve closed more than 5 seconds unless you are 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 must be replaced.
4. With the shutoff valve in the open position check the gear housing for leaks by holding the wheel fully in one direction against its stop and checking fluid pressure against specifications. Do not hold the wheel in this position for too long. Power steering systems easily reach pressures in excess of 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 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 bad and must be replaced.
