Pump failures caused by the bypass valve, seals, bearings and stator wear, plus preventive maintenance and testing with the MS611 and MS603N.
A failed power steering system impairs both comfort and safety. The main causes of pump failure are:
- A bypass valve damaged by old oil or overheating from holding the wheel at full lock, causing heavier steering when warm and pump noise
- Leaks from worn seals and gaskets, lowering the fluid level
- Bearing wear from shocks, vibration or incorrect installation
- Insufficient pressure due to wear of the intake plate or stator surface
Most failures stem from neglected maintenance: change the fluid about every 15,000 km while flushing the system, and use good-quality, suitable oil. The pump can be tested in the vehicle with the MS611 tester or on the MS603N bench.