Power Steering Pump Noise

Bleeding Air from the Power Steering System: Proper Procedure

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Trapped air causes whine, groan, and foamy fluid. Here’s the correct bleeding procedure that actually works — no special tools needed.

What the Driver Feels

  1. Whine or groan after a pump replacement or fluid service
  2. Fluid looks foamy or milky in the reservoir
  3. Steering feels spongy or vague
  4. Noise that changes as you rev the engine
  5. Fluid level drops after a few days of driving
  6. Pump makes a gurgling sound
  7. Noise after disconnecting any power steering line
  8. Return hose sucks flat when the engine runs

What Causes It

Any time you open the power steering system — pump replacement, hose replacement, rack replacement — air enters. If you don’t bleed it properly, the new pump will whine just like the old one. On the Honda Accord and Toyota Camry}, the system is especially prone to trapped air because the rack sits higher than the reservoir.

The wrong bleeding technique (just running the engine and turning the wheel) doesn’t work — air gets trapped in the rack and lines. The correct method is to bleed with the engine OFF first, pushing the air back to the reservoir, then run the engine.

How to Inspect

Important: Do not hold the wheel at full lock for more than a few seconds during bleeding.

1. Jack up the front of the vehicle so the front wheels are off the ground.

2. Fill the reservoir to the MAX cold mark with correct spec fluid.

3. With the engine OFF, turn the steering wheel lock-to-lock slowly 15-20 times. This pushes fluid through the system and forces air back to the reservoir.

4. Let the vehicle sit for 5-10 minutes so air bubbles rise to the reservoir.

5. Start the engine and let it idle for 1 minute. The fluid level will drop — top it off.

6. Turn the wheel lock-to-lock a few more times. Watch the reservoir for bubbles.

7. Lower the vehicle and road test for 10 minutes. Recheck the level.

Recommended Repair

  1. If air persists after bleeding, check the suction hose for cracks — it’s drawing air in.
  2. Replace the reservoir cap if the diaphragm is torn (lets air in).
  3. Some European cars (BMW, Mercedes) require a vacuum bleeder — a hand pump that pulls fluid through under vacuum.
  4. After 50 miles, recheck the fluid level — trapped air will work itself out and the level will drop.
  5. If the fluid is still foamy after 100 miles, there’s a leak in the suction side that needs fixing.

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