1994-2001 Subaru Impreza Power Steering Pump: Fixing Whines, Leaks, and Stiff Steering

Symptoms of a Failing Power Steering Pump

A failing power steering pump on a 1994-2001 Subaru Impreza will give several distinct warning signs. Paying attention to these symptoms can help you diagnose the problem before it leads to a complete loss of steering assist.

Common Failure Symptoms:

• Whining or Groaning Noises: This is the most common symptom. The noise is often most noticeable when the engine is cold or when turning the steering wheel. It typically changes pitch as the engine RPMs increase. This sound is often caused by air entering the system (cavitation), low fluid levels, or internal wear within the pump itself.
• Stiff or Heavy Steering: If turning the steering wheel, especially at low speeds or when parking, requires significantly more effort than usual, the pump may not be generating enough hydraulic pressure. This can be a constant issue or happen intermittently.
• Squealing on Startup: A loud squeal when you first start the car can point to a failing pump, but it can also be caused by a loose or worn-out drive belt. If the belt is in good condition, the pump's bearing is the likely suspect.
• Fluid Leaks: The power steering system is sealed and should not lose fluid. If you see reddish or light brown fluid under the front of your car, it's likely a power steering leak. Leaks can come from the pump body, the seals, or the connected hoses.
• Metal Flakes in Fluid: If you check the power steering fluid and it appears grey or has shiny metallic particles in it, this is a critical sign that the pump is internally destroying itself. Continuing to run the engine will circulate these particles throughout the steering rack, potentially causing much more expensive damage.

Known Issues, Recalls, and TSBs

For the 1994-2001 Impreza, there are no specific recalls or Technical Service Bulletins (TSBs) from the National Highway Traffic Safety Administration (NHTSA) directly concerning power steering pump failure. However, Subaru has issued TSBs for later models regarding groaning noises caused by the internal relief valve and increased steering effort in cold temperatures, indicating a history of refining pump design. The most significant issue for this generation is not a defect, but a compatibility trap.

Variant Differences & Compatibility Warnings

Engine size is the most critical factor when ordering this part. The power steering pumps are NOT interchangeable between all engines in this generation.

• 1.8L Engines: Use a specific pump.
• 2.2L & 2.5L Engines: Use a different pump.

Buying a Used Power Steering Pump

A used OEM power steering pump can be a reliable and cost-effective alternative to expensive new parts, especially when cheap aftermarket options may have questionable quality. Here’s what to look for when buying a recycled pump.

• Physical Inspection: Check the pump housing for any cracks or significant corrosion. Ensure the pulley is not bent or cracked and spins freely by hand without grinding or excessive noise. Check the threaded ports for the high-pressure and low-pressure lines to make sure they are not stripped or damaged.
• Shaft Play: Try to wiggle the pulley shaft. A small amount of in-and-out movement is sometimes normal, but excessive side-to-side or up-and-down play indicates a worn bearing, and you should pass on that pump.
• Verify Compatibility: Double-check that the pump came from an Impreza with the same engine size as yours (1.8L, 2.2L, or 2.5L). If possible, compare the part number on the used pump to the list of known OEM numbers.
• Mileage Considerations: While these pumps are generally durable, they are a wear item. A pump from a vehicle with under 150,000 miles is generally a safe bet. Pumps from lower-mileage vehicles are always preferable.
• Why Used OEM is a Good Choice: Original Equipment Manufacturer (OEM) pumps were built to Subaru's specific standards for materials and tolerances. A used OEM pump from a reputable recycler is often a better choice than a new, cheaply made aftermarket pump, which may use lower-quality bearings or seals that can fail prematurely.

Replacement & Installation Tips

Replacing the power steering pump is a moderately difficult job that a DIY mechanic with the right tools can accomplish in a few hours.

Special Procedures & Torque Specs

• Fluid Type: This is critical. Subarus of this era do NOT use standard "power steering fluid." They use Automatic Transmission Fluid (ATF). Using the wrong fluid can damage the seals and the pump. Look for a fluid that meets Dextron II or Dextron III specifications.
• Bleeding the System: This is the most important step after installation. Failure to properly bleed the air out of the system will cause the new pump to whine loudly and can lead to premature failure.
1. With the engine OFF, raise the front wheels off the ground.
2. Fill the reservoir to the "Full Cold" mark with ATF.
3. Slowly turn the steering wheel from full lock to full lock (all the way left, then all the way right) about 10-15 times. You should see bubbles coming up in the reservoir.
4. Check the fluid level and top it off as it drops. Keep doing this until the fluid level remains steady and you no longer see bubbles.
5. Only once the air is purged should you start the engine. Check for noise and top off the fluid one last time.
• Torque Specs: The bolts holding the pump and bracket are threaded into aluminum, so be careful not to overtighten. The banjo bolt for the high-pressure line should be torqued to approximately 29 ft-lb (39 N·m). The smaller bracket bolts are typically torqued to around 16 ft-lb.

Related Parts

When replacing the power steering pump, it's a good idea to inspect and consider replacing these related parts at the same time:

• Drive Belt: If the belt is cracked, glazed, or worn, replace it.
• Hoses: Inspect the high-pressure and low-pressure (suction) hoses for cracks, brittleness, or leaks. The suction hose is a common failure point that can cause air to enter the system.
• Inlet O-Ring: Always replace the small O-ring on the low-pressure inlet pipe. It's a cheap part that prevents the most common cause of pump whine.

Cost Comparison

Frequently Asked Questions (FAQ)