Role of the Power Steering Pump

The vane-type hydraulic power steering pump is a component that helps assist steering operations.
It is driven by a belt connected to the engine’s crankshaft, which turns the pump pulley. Inside the pump, fluid is pressurized and then sent to the power steering rack.
This hydraulic pressure helps ensure that the steering smooth and easy to operate, especially at low speeds when the tires experience greater friction against the road surface.

Structure and Operation of a Vane-Type Oil Pump

The vane-type oil pump is a hydraulic pump driven by the engine via a belt.
Inside the pump, there are components such as a rotor, vanes, and a cam ring. As the rotor spins, the vanes are pushed outward by centrifugal force and slide along the cam ring.
This movement causes the internal volume of the pump to change, drawing in and pushing out fluid as a result.

Flow Control and Excess Pressure Management

Since the amount of fluid discharged by the pump increases with engine speed, excess fluid may be delivered at high RPMs.
To prevent over-supply, a flow control valve automatically redirects excess fluid back to the reservoir.
This helps maintain stable hydraulic pressure, prevents unnecessary strain on the system, and reduces fluid degradation.

Wear Over Time and the Importance of Overhauling

Internal components such as seals and bearings can wear out over time.
This may lead to fluid leaks, unusual noises, or reduced hydraulic pressure.
To restore the pump’s original performance and ensure long-term reliability, it is recommended to perform an overhaul which includes disassembly, cleaning, and replacement of worn parts before major issues occur.

Common Symptoms and Possible Causes of Failure

• Fluid leaks
  • Deterioration of oil seals and O-rings
  • Worn shaft surfaces
  • Deteriorated hoses, cracks in piping, or loose connections
• Unusual noise from the pump and fluid foaming in the reservoir tank (cavitation)
  • Wear of vanes or cam ring
  • Bearing wear and deterioration
  • Insufficient lubrication due to low fluid level
• Heavier steering operation
  • Low fluid level
  • Worn vanes or reduced pump pressure
  • Flow control valve malfunction
  • Loose or worn power steering belt
  • Power steering rack problems and failures