Power Steering Terminology You Need to Know

When you have issues with your power steering system, it’s important to know all the terminology. Are tackling this issue yourself, or do you have a mechanic who’s going to explain what exactly went wrong in your power steering system? Either way, this list of components in your Subaru’s power steering system will come in handy.

1. Power Steering Fluid

Power steer fluid

The power steering fluid is a petroleum-based hydraulic fluid that provides pressureto move the steering rack. The fluid is stored in the power steering reservoir and it’s pushed to the rack and pinion by the pump located within the power steering system.

The power steering fluid could leak from many different places. Commonly it leaks from the pressure hose, return hose, or power steering pump. To replenish your power steering fluid, pop the hood and then pour the fluid into the reservoir. There should be a cap labeled “power steering fluid”. Be sure to check your owner’s manual to find out the correct type of power steering fluid to use.

2. O-Ring

Steer o ring

Image Credit: BarManBean

Often times, the o-ring is the culprit behind a leaking power steering pump. Located at the inlet and outlet connections of the pump, o-rings are rubber seals designed to prevent the fluid from leaking out. It’s common for an o-ring to deteriorate over time due to:

  • Abrasion
  • Chemical reactions
  • Compression
  • Installation damage
  • Degradation due to age

When an o-ring fails, you don’t have to buy a whole new power steering pump. Instead, you can order an OEM o-ring and only replace the bad one.

3. Power Steering Fluid Reservoir

Power steer resevoir

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Usually located near the firewall, the power steering fluid reservoir’s contains the power steering fluid. The reservoir is connected to the pump via a hose, and the pump draws the fluid out of the reservoir whenever necessary. The fluid is then returned to the reservoir via a return line after having been run through the system. On modern cars, the reservoir can be identified by its cap, which is labeled “power steering fluid”.

4. Pressure Line Hose

Pressure line hose

The power steering pump has two hose connections. One for a pressure line hose, and the other one for a return hose. The pressure line hose is designed to handle the high hydraulic pressure created by the pump as it feeds the steering rack.

5. Return Hose

Return hose

When the fluid is done being pumped through the system, it returns to the reservoir through the return hose.

6. Serpentine Belt

Serpentine belt

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A serpentine belt goes around the power steering pump pulley and several other engine accessories. Sometimes called a steering belt or V belt on older cars, it serves as a link between the pump and the engine. With proper tension the belt will spin the pump to provide hydraulic pressure.

Sometimes the belt will lose tension. When that happens, the pump won’t get the power it needs to function properly. The best thing to do is to replace it with a new OEM serpentine belt right away.

7. Rack and Pinion Steering Gears

Steer gears

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The rack and pinion steering gears are responsible for moving the wheels left or right according to which way you turn the steering wheel. The pinion is connected to the steering shaft. When the shaft turns, the pinion moves the rack in the desired direction. The rack is connected to both tie rods, which are connected to the steering knuckles.

8. Filter

Steer filter

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There’s a filter within the power steering system that filters the steering fluid before it’s pumped through the system. The filter is supposed to be checked (and replaced if necessary) every two years.

9. Power Steering Flush

Steer flush

Image Credit: Masfebriyan

A power steering flush is when you flush the fluid out of the entire system. It’s done by draining fluid out of the reservoir and system and then refilling the reservoir with fresh steering fluid. It’s routine to inspect the seals and hoses while flushing out the system. You want to flush out your system at regular intervals, which are delineated in your owner’s manual.

10. Pressure Switch

Steer switch

The pressure switch detects the amount of pressure in the power steering system and communicates the information to the ECU. The ECU adjusts the engine’s power accordingly. It is intended to give the engine a little more gas when steering at low speeds. It’s common for a pressure switch to deteriorate over time due to excessive heat. If you’re experiencing any of these issues when turning at low speeds, then you should have your pressure switch checked:

  • Stalling
  • Engine slowing down
  • Engine operating at erratic speeds