How Long It Takes to Get Air Out of a Power Steering System

Expect 15–45 minutes for a standard manual bleed, 5–15 minutes with a vacuum bleeder, and up to a few short drives for residual microbubbles to clear; if noise or foam persists beyond an hour of proper bleeding or over the next day, there’s likely a leak, wrong fluid, or a component issue. Air trapped in a hydraulic power steering system causes groaning, foaming, and heavy steering, and removing it efficiently depends on the method, the vehicle design, and how much air entered in the first place.

What Determines the Time Required

Several variables affect how quickly a power steering system purges air. Understanding these helps set realistic expectations and avoid damaging the pump by running it aerated.

• How the air got in: Minor reservoir level drops purge faster; hose or rack replacement can inject large volumes of air that take longer to clear.
• Bleeding method: Vacuum bleeding is quickest; manual cycling is slower; some systems self-bleed over multiple drive cycles.
• System design: Remote reservoirs, long hose runs, or hydro-boost brakes can extend bleed time; some electro-hydraulic/active steering systems require scan-tool routines.
• Fluid type and condition: Correct, fresh fluid de-aerates faster; wrong fluid or contamination can prolong foaming.
• Temperature: Cold fluid traps bubbles longer; warm—but not hot—fluid bleeds faster.
• Component health: Worn pumps, loose fittings, or suction-side leaks keep pulling in air and prevent a successful bleed.

Taken together, these factors explain why one car quiets in minutes while another needs repetitions, cooling periods, or specialized tools to finish the job.

Typical Timelines by Method

Manual Bleed (Most Common, No Special Tools): 15–45 Minutes

This approach works for most hydraulic systems after minor repairs or fluid changes and can be done at home with jack stands.

1. Raise the front wheels off the ground, secure the vehicle, and fill the reservoir with the exact fluid specified by the manufacturer.
2. With the engine OFF, turn the steering wheel slowly from lock to lock 15–30 times, pausing near—but not grinding into—the stops. Keep the fluid topped up as bubbles purge.
3. Let the system sit 5–10 minutes to let foam separate; top up again if the level drops.
4. Start the engine and let it idle. Slowly turn lock to lock 5–10 times, holding at each end no more than 2–3 seconds. Do not let the reservoir run low.
5. Shut off the engine, recheck level and clarity (look for microbubbles/foam). Repeat short cycles if mild noise remains.
6. Lower the vehicle and test-drive gently, avoiding prolonged full-lock turns; recheck level and appearance afterward.

Done correctly, this clears most systems within half an hour; stubborn foam may require a cool-down and a second round.

Vacuum Bleed (Fastest, Cleanest): 5–15 Minutes

Using a hand vacuum pump and an appropriate reservoir adapter speeds de-aeration and reduces pump cavitation.

1. Fill the reservoir with the correct fluid and attach a vacuum adapter to seal the reservoir.
2. Apply 20–25 inHg of vacuum and hold for 3–5 minutes, topping up fluid as the level drops and bubbles rise.
3. Release vacuum, start the engine at idle, and briefly reapply vacuum while slowly cycling the wheel a few times.
4. Remove the tool, set final fluid level, and verify quiet operation and normal assist.

This method often eliminates aeration in a single session and is recommended after major component replacements.

Self-Bleeding Over Drive Cycles: Hours to a Few Days

Some systems gradually purge residual microbubbles during normal driving after an initial manual bleed.

• Expect minor hiss or faint whine to fade over 20–50 miles or 1–3 days.
• Monitor the reservoir for foam; recheck and top up when cold.

If noise worsens or fluid keeps foaming, stop and inspect for suction leaks or wrong fluid—continued driving can damage the pump.

After Major Repairs or on Active/Electro-Hydraulic Systems: 20–60 Minutes

Rack-and-pinion, hose, or pump replacements may trap large air pockets; some vehicles with hydro-boost or active steering require factory bleed routines.

• Use service-manual procedures, sometimes with a scan tool to command valves/pumps.
• Combine vacuum bleeding with controlled wheel cycling and cool-down intervals.

Plan for a longer session and follow the exact fluid and procedure specifications to avoid recurring aeration.

Troubleshooting If It’s Taking Too Long

If the system won’t quiet down after a thorough bleed, look for root causes that continually introduce or retain air.

• Suction-side leaks: Loose clamps, cracked return hoses, hardened O-rings at the pump inlet, or porous fittings draw air without dripping fluid.
• Incorrect fluid: Some systems require specific CHF or ATF types; wrong viscosity can foam persistently.
• Over-aggressive steering inputs: Fast, full-lock sweeps churn foam; go slow and avoid holding at full lock.
• Contamination: Sludge or metal debris can aerate fluid and damage pump vanes; a flush and filter (if equipped) may be necessary.
• Failing pump or rack: Internal cavitation or seal failure recirculates air; component replacement may be required.
• Trapped high-point air: Lines routed above the reservoir can retain pockets; vacuum bleeding helps dislodge them.

Addressing these issues usually resolves persistent aeration more effectively than repeating the same bleed process.

Safety and Best Practices

Bleeding is straightforward, but a few habits prevent pump damage and messy setbacks.

• Never let the reservoir run low—top up frequently with the exact specified fluid.
• Avoid holding the wheel at full lock for more than 2–3 seconds; this spikes pressure and heats fluid.
• Work with the front wheels off the ground for initial cycles to reduce load on the pump and rack.
• Allow cool-downs if the fluid starts to foam or the pump whines; hot, aerated fluid bleeds poorly.
• Clean spills promptly; belt slippage from oily pulleys can mimic steering issues.
• Verify torque and seal condition on suction and pressure fittings after any repair.

Following these practices protects components and speeds the de-aeration process, saving time and avoiding repeat work.

When to Stop and Recheck

Stop and reassess if the pump whine is loud after 30–45 minutes of proper bleeding, the reservoir keeps foaming, the steering feels jerky or heavy, or the fluid turns milky. Persistent symptoms point to leaks, wrong fluid, or failing parts rather than a normal bleed-in period.

Summary

Most power steering systems purge air in 15–45 minutes with a careful manual bleed, or in 5–15 minutes using a vacuum bleeder. Residual microbubbles may clear over a few short drives, but ongoing noise or foam signals an underlying issue—typically a suction leak, wrong fluid, or a failing component—that needs correction before further bleeding will help.

What happens if air gets in a power steering system?

Air. And power steering symptoms. There are several symptoms of having air in the power steering. These are some of them. Number. One you feel vibration on the steering wheel.

How to get air out of a power steering system?

To bleed air from a power steering system, fill the reservoir, then slowly turn the steering wheel from full lock to full lock with the engine off, making sure to add fluid as the level drops to prevent more air from entering. Once the fluid level stabilizes, restart the engine and repeat the lock-to-lock turns until air bubbles stop appearing in the reservoir and the steering feels normal. 
Steps to Bleed the Power Steering System

1. Prepare the Vehicle
   • Park your car on a level surface with the engine off and let it cool down. 
   • Locate the power steering fluid reservoir under the hood. 
   • With the engine off, remove the reservoir cap and ensure the fluid level is at the appropriate mark (e.g., “Full Cold”). Add the correct type of power steering fluid if needed, but do not overfill. 
2. Bleed the System (Engine Off) 
   • Leave the reservoir cap off. 
   • Slowly turn the steering wheel from the fully left position to the fully right position. 
   • Continue turning the wheel back and forth, stopping in the center each time to check the fluid level. 
   • Add fluid as needed to keep the reservoir from running low. 
   • Repeat this process until the fluid level remains constant and no more bubbles are visible. 
3. Start the Engine 
   • Once the fluid level is stable with the engine off, start the engine. 
   • With the engine idling, slowly turn the steering wheel from lock to lock again. Avoid holding the wheel at the extreme ends (lock stops), as this can put stress on components. 
   • Continue turning the wheel back and forth until the fluid level is stable and you no longer see any air bubbles. 
4. Final Check
   • Shut off the engine and check the fluid level in the reservoir one last time. 
   • The fluid level should remain stable, and the steering should no longer feel stiff or noisy. 
   • If air persists, repeat the process, and if the problem continues, it may indicate a leak or a failing component, according to Quora users. 

Do you leave the cap off when bleeding power steering?

You should bleed the power steering system with the reservoir cap off to allow trapped air to escape. The process involves filling the reservoir with the correct fluid, then slowly turning the steering wheel from full left to full right multiple times with the engine running, while continuously monitoring and topping off the fluid level to prevent new air from entering the system.
 
This video demonstrates the process of bleeding power steering fluid: 52s4DIYersYouTube · Jul 1, 2016
Steps to bleed the power steering system:

1. Prepare the vehicle: Park on a level surface, chalk the rear wheels, and lift the front end with a jack and jack stands so the front tires are off the ground. 
2. Locate the reservoir: Find the power steering fluid reservoir under the hood. 
3. Fill with fluid: Remove the reservoir cap and fill the reservoir to the manufacturer-recommended level using the correct power steering fluid for your vehicle. 
4. Start the engine: With the reservoir cap still off, start the engine. 
5. Turn the steering wheel: Slowly turn the steering wheel from full left to full right, making several complete cycles. 
6. Monitor fluid level: As you turn the wheel, check the fluid level and add more fluid as needed to keep it from dropping below the minimum level. This prevents more air from being sucked into the system. 
7. Repeat until clear: Continue this process until the fluid in the reservoir is no longer bubbling or foamy, which indicates the air has been purged. 
8. Top off and finish: Once the air is out, shut off the engine, top off the fluid to the correct level, and replace the reservoir cap. 

Important considerations:

• Use the right fluid: Always use the power steering fluid recommended by your vehicle’s manufacturer. 
• Don’t hit the stops hard: Avoid turning the wheel so forcefully that it hits the steering stops, as this can cause more air to enter the system. 
• Check for bubbles: If the fluid looks bubbly or foamy, shut the engine off and let it sit for a few minutes to allow the foam to settle before repeating the bleeding process. 

Is it safe to drive with air in power steering?

Risk of Damage: Continuing to drive with a leak can lead to further damage to the power steering system, including the pump and steering rack, which can be costly to repair. Recommendation: It’s best to have the leak repaired as soon as possible to avoid potential safety issues and expensive repairs.