2009-10 Forester & 2008-11 Impreza Power Steering Pump: Fixing Whining Noises and Stiff Steering

Symptoms of a Failing Power Steering Pump

A problem with the power steering system can show up as strange noises, a change in steering feel, or visible leaks. It's important to identify the specific symptom, as it can point to whether the pump is truly bad or if a simpler, related part is the culprit.

Noises: Whining, Groaning, or Squealing

• Whining Noise: The most common symptom is a distinct whining or buzzing noise that gets louder when you turn the steering wheel and often changes pitch with engine RPM. This is frequently caused by air getting into the power steering fluid. Before you condemn the pump, check for a failed O-ring on the fluid inlet.
• Groaning at Full Lock: A deep groaning or moaning sound that only happens when the steering wheel is turned all the way to the left or right can indicate a problem with the pump's internal pressure relief valve.
• Squealing on Startup: A loud squeal when you first start the engine, especially on a cold day, may not be the pump itself but a loose or worn-out serpentine belt that drives the pump.

Changes in Steering Feel

• Stiff Steering: The steering wheel becomes difficult to turn, especially at low speeds or when parking. This indicates a loss of hydraulic assistance.
• Jerky or Inconsistent Steering: The power assist feels like it's cutting in and out, making the steering feel unpredictable.

Fluid Leaks and Condition

• Visible Leaks: You may find puddles of reddish or light brown fluid under the front of your car. While the pump itself can leak, it's also common for the hoses or the inlet O-ring to be the source.
• Contaminated Fluid: If you check the power steering reservoir and the fluid is dark, has a burnt smell, or contains shiny metal particles, it's a strong sign of internal pump wear.

Known Issues, TSBs, and Recalls

For the 2009-2010 Forester and 2008-2011 Impreza with the 2.5L non-turbo engine, the power steering system is generally reliable, but one issue is extremely common and often misdiagnosed as a failed pump.

The Infamous Whining Noise O-Ring (Part No. 34439FG000)

The number one complaint for these vehicles is a power steering pump that whines, especially in cold weather. In the vast majority of cases, the pump is not faulty. The problem is a small, inexpensive rubber O-ring on the fluid suction inlet fitting on top of the pump. Over time, this O-ring hardens and shrinks, allowing air to be sucked into the system. This aerated fluid is what causes the pump to whine loudly.

Technical Service Bulletins (TSBs)

Subaru issued TSB 04-13-09R, which applies to the 2004-2011 Impreza and 2003-2008 Forester. It addresses a groaning noise heard when the steering is at full lock. The bulletin states this can be caused by a vibrating pressure relief valve inside the pump. Instead of replacing the entire pump, a new relief valve can be installed to fix the noise.

Recalls

As of this writing, there are no active NHTSA safety recalls for the power steering pump on the 2009-2010 Subaru Forester or 2008-2011 Subaru Impreza.

Diagnosing the Problem

Don't assume you need a new pump right away. Follow these diagnostic steps to pinpoint the real issue.

1. Check the Fluid: Open the power steering reservoir (it's often marked with a steering wheel icon). Check the fluid level. If it's low, you have a leak. Note the fluid's color and smell. It should be a reddish color (it uses ATF). If it's dark brown, black, or has metal flakes, the pump or rack may be failing internally.
2. Inspect the Belt: Check the condition of the serpentine belt that drives the pump. If it's cracked, glazed, or loose, it can slip and cause squealing or a loss of power assist.
3. Find the Leak Source: If the fluid is low, clean the pump, hoses, and reservoir area thoroughly. Start the engine and have a helper turn the wheel while you look for the source of the leak with a flashlight. Pay close attention to the O-ring on the inlet pipe, the hose clamps, and the seams of the pump body.
4. Isolate the Noise: If the main symptom is a whining noise, the cause is almost certainly air in the system. The most likely entry point is the inlet O-ring.

Buying a Used Power Steering Pump

A quality used OEM power steering pump is an excellent alternative to expensive new units or potentially unreliable aftermarket parts. Since the original Subaru pumps are well-built, a low-mileage used unit can provide many years of service. Here’s what to look for:

• Verify Compatibility: This pump fits 2.5L non-turbo engines only. It is not compatible with WRX, STI, or other turbocharged models, which use a different pump with different pressure specifications. Ensure the part numbers (34430FG010, 34430FG011, etc.) match.
• Physical Inspection: Check the aluminum housing for any cracks or heavy corrosion. Inspect the pulley for any dents or chips that could damage the belt. The pulley should spin smoothly by hand with no grinding or excessive side-to-side wobble.
• Check for Leaks: Look for signs of fluid leakage from the main shaft seal (behind the pulley) or from the seams of the pump body. Some wetness around the inlet/outlet ports is normal, but heavy, caked-on grime can indicate a significant leak.
• Mileage Isn't Everything: Failure is often due to age (hardened seals) rather than high mileage. A lower-mileage pump is generally better, but a well-maintained, higher-mileage unit can still be a good part. Aim for a pump from a vehicle with under 100,000 miles if possible.
• Why Used OEM is a Good Choice: Original Subaru pumps are built to precise pressure specifications for the vehicle's steering rack. Some cheap aftermarket pumps can be noisy out of the box or provide incorrect assist levels, leading to poor steering feel. A recycled OEM part ensures correct fitment and performance.

Replacement Overview & Fluid Requirements

Replacing the power steering pump is a moderately difficult job that a skilled DIY mechanic can perform in a few hours. The key challenges are accessing the bolts and properly bleeding the system afterward.

Key Replacement Steps:

1. Loosen the accessory belt tensioner and remove the belt from the power steering pump pulley.
2. Place a drain pan underneath and disconnect the high-pressure and low-pressure fluid lines from the pump. Be prepared for fluid to spill.
3. Unbolt the pump from its mounting bracket. Access to the rear bolts can be tight.
4. Transfer the pulley from the old pump to the new one if necessary.
5. Install the new pump and reconnect the fluid lines (it's a good idea to replace the inlet O-ring at this time). Torque mounting bolts to approximately 16 ft-lbs.
6. Reinstall the accessory belt and tension it correctly.
7. Flush and Bleed the System: This is the most critical step. Fill the reservoir with fresh ATF-HP. With the front wheels off the ground, turn the steering wheel slowly from lock to lock about 20-40 times with the engine OFF to work the air out. Check and top off the fluid level. Finally, start the engine and repeat the lock-to-lock turning until no more bubbles appear in the reservoir and the pump is quiet. Failure to bleed the system will result in a noisy pump and potential damage.

Related Parts to Replace

• Inlet O-Ring (34439FG000): Always replace this, even if you are installing a new pump.
• Serpentine Belt: If the old belt is cracked, worn, or contaminated with fluid, replace it now.
• Fluid Hoses: Inspect the suction and return hoses. If they are hard, brittle, or cracked, they can also leak or introduce air into the system.

Cost to Replace the Power Steering Pump

The cost can vary significantly depending on the type of part you choose and whether you do the work yourself.

Frequently Asked Questions (FAQ)