ASE A4 Suspension and SteeringSteering System Diagnosis and RepairHard
A technician is performing a diagnostic test on a hydraulic power steering system that is exhibiting hard steering. With the engine running and the steering wheel turned to full lock, a pressure gauge connected to the high-pressure line reads significantly lower than the manufacturer's specified maximum pressure, and the power steering pump is making excessive noise. What does this indicate?
- AA faulty power steering pump.
- BA leaking power steering gear internal seal.
- CA restricted high-pressure line.
- DAn improperly adjusted steering gear.
Show answer & explanationAnswer & explanation
Correct answer: A. A faulty power steering pump.
If the maximum pressure at full lock is significantly lower than specified, and the pump is noisy, it points directly to a faulty power steering pump that is unable to generate or maintain adequate hydraulic pressure. The full lock test is designed to test the pump's maximum output.
Why the other options are wrong
- B. A leaking power steering gear internal seal would cause hard steering by diverting pressure, but the pump would still be attempting to produce maximum pressure, which might still be within spec (or even higher) at the pump outlet, with the pressure drop occurring within the gear itself. The primary indicator here is the pump's *output* being low.
- C. A restricted high-pressure line would typically cause a *higher* pressure reading before the restriction and potentially pump damage, not a significantly lower maximum pressure at full lock.
- D. An improperly adjusted steering gear would typically cause play or binding, not a direct reduction in the pump's maximum pressure output.
Power Steering Pump Pressure Test
A pressure test evaluates the power steering pump's ability to generate and maintain specified hydraulic pressure, particularly at full steering lock.
- Connects a gauge to the high-pressure line.
- Tests maximum pressure at full lock (briefly).
- Low pressure indicates a weak or faulty pump.
- Excessive noise during test can also point to pump issues.
Memory trick: Pump Pressure Problems Produce Poor Performance.