Most steering systems use a rack and pinion. As the steering wheel is turned, the teeth on the pinion gear at the end of the steering shaft move the steering rack left or right. The steering linkages and tie rod ends then force the front wheels to change angle. A power steering pump pressurizes hydraulic fluid. When the steering wheel turns, a valve in the rack and pinion assembly opens, allowing pressurized fluid to help move the steering rack in the desired direction.
How does the steering system fail?
Tie rod ends are constructed with a ball inside a socket, with a lining injected to keep the ball tight. The lining wears out over time, or can be damaged as a result of a steering impact such as hitting a kerb. Rubber hoses and metal lines carry the pressurized fluid from the power steering pump to the rack and pinion. Hoses can eventually fail - mostly where the metal and rubber sections meet. The power steering pump turns whenever the engine is running. Pump seals, and internal parts can eventually fail - especially when power steering fluid becomes contaminated, or when the fluid level is low as a result of a leaking hose. Seals can also fail in the steering rack and pinion resulting in fluid loss or reduced steering assistance.
Results of failure:
Worn tie rod ends result in excessive free play - causing premature tire wear, and in extreme cases, the loss of steering control should the ball and socket become separated. An internally damaged power steering pump doesn’t generate enough fluid pressure, which can make the steering hard to turn at low engine speeds.
Required Service or Repairs:
Steering linkages should be inspected and replaced if free play is found. Power steering fluid should be inspected nd replaced according to the manufacturer's recommendation or if contaminated