How to Bleed Air Out of a Power Steering Pump

The quickest way to bleed air from a hydraulic power steering system is to raise the front wheels, fill the reservoir with the correct fluid, turn the steering wheel slowly from lock to lock several times with the engine off, then repeat with the engine idling while topping up fluid; if noise or foaming persists, use a vacuum bleeder and check for suction-side leaks. This process removes trapped air that causes whining, foamy fluid, and heavy steering, restoring smooth, quiet operation.

How to tell if air is in your power steering system

Before bleeding, confirm the symptoms point to aeration. Air in the system often appears after low fluid, hose or pump replacement, or a leak. Recognizing the signs helps you decide whether a standard bleed will suffice or if a deeper check is needed.

• Whining or groaning from the pump, especially right after start-up or when turning
• Foamy or milky-looking fluid in the reservoir
• Intermittent assist or a “choppy” feel when turning the wheel
• Bubbles visible in the reservoir after the engine runs
• Fluid level repeatedly dropping due to air working out (or due to an actual leak)

If these symptoms are present, bleeding the system is the correct next step; persistent noise after bleeding typically indicates a leak or component issue that also needs attention.

What you’ll need

Gather basic safety gear and the right fluid before you begin. Using the specified fluid is critical—many modern systems require dedicated power steering fluid or CHF fluid, not ATF.

• Correct power steering fluid for your vehicle (check owner’s/service manual or cap)
• Floor jack and jack stands (or a lift) to raise and support the front axle safely
• Shop towels and a drain pan
• Safety glasses and gloves
• Optional but helpful: Hand vacuum pump with power steering adapter cap
• Flashlight to inspect for leaks

Having these items on hand ensures the process goes smoothly and reduces the risk of spills or missed issues.

Standard bleeding procedure (most hydraulic systems)

This method works for the majority of belt-driven hydraulic power steering systems with a conventional pump and reservoir. It purges air gradually without stressing the pump.

1. Park on a level surface, set the parking brake, and chock the rear wheels. Raise the front of the vehicle and support it securely on jack stands so both front wheels are off the ground.
2. With the engine off and the steering unlocked (key in ACC if needed), check and fill the reservoir to the “COLD” or “MIN” mark using the correct fluid.
3. Slowly turn the steering wheel from full left lock to full right lock 15–20 times. Move smoothly—do not slam against the stops. Watch the reservoir for bubbles; top up fluid as the level drops.
4. Let the vehicle sit for 5–10 minutes to allow trapped bubbles to rise. Refill to the correct level if it drops.
5. Start the engine and let it idle. Do not rev the engine. Observe the fluid; a few small bubbles at first can be normal. If the fluid violently foams, shut the engine off and let it settle before continuing.
6. With the engine idling and wheels still off the ground, slowly turn the wheel from lock to lock 5–10 times. Avoid holding the steering at full lock for more than 2–3 seconds to prevent pump stress.
7. Shut the engine off. Let the system rest for 5–10 minutes, then recheck the level and top off to the proper mark. Inspect for leaks around hoses, fittings, and the rack/gear.
8. Lower the vehicle. Road-test with gentle turns and parking maneuvers. Recheck fluid level and clarity afterward; it should be free of foam and near silent.

After a proper bleed, steering should be smooth and quiet. If noise or bubbles persist, repeat the cycle once; if still present, proceed to a vacuum bleed and inspect for leaks on the suction side.

Vacuum-bleed method (for stubborn air or when specified by the manufacturer)

Some systems trap air pockets that are hard to purge with turning alone. Applying vacuum to the reservoir de-aerates the fluid more effectively and is recommended by several OEMs after component replacement.

1. Ensure the reservoir is filled to the correct level with the specified fluid.
2. Attach a power steering vacuum adapter cap to the reservoir and connect a hand vacuum pump.
3. Apply 20–25 inHg (inches of mercury) of vacuum and maintain it for 5–10 minutes. You may see bubbles rising into the reservoir during this time.
4. While maintaining vacuum, gently turn the steering wheel lock to lock a few times (engine off), then release and reapply vacuum as needed to keep 20–25 inHg.
5. Release vacuum, recheck fluid level, and top up as needed. Start the engine and let it idle for 1–2 minutes, then repeat a brief vacuum cycle if small bubbles remain.
6. Finish with a short lock-to-lock sequence at idle and verify quiet operation and stable fluid level.

Vacuum bleeding accelerates de-aeration and often eliminates residual pump whine. If noise continues afterward, focus on leak diagnosis and component condition.

Safety notes and key tips

Following best practices helps prevent pump damage and ensures a clean, effective bleed. Keep these points in mind during and after the procedure.

• Do not hold the steering at full lock for more than 2–3 seconds, especially with a cold system.
• Use only the specified fluid. Many European systems require CHF 11S/202 or similar; some older vehicles accept ATF; others need dedicated PSF.
• Keep the reservoir at the correct level—do not overfill. Fluid expands when hot.
• Check the drive belt for condition and proper tension; a slipping belt mimics pump whine.
• Fix leaks first. Air commonly enters on the suction side: reservoir-to-pump hose, clamps, or the pump inlet O-ring (notably on many Honda/Acura models).
• Some reservoirs have internal filters that clog; if fluid stays foamy or flow seems restricted, replacing the reservoir may be required.

Adhering to these tips reduces the chance of repeat aeration and extends pump and rack life.

Special cases and exceptions

Not every steering system bleeds the same way. Identify your setup to avoid damage and wasted effort.

• Electric Power Steering (EPS): No hydraulic fluid—there’s nothing to bleed.
• Electro-hydraulic (EHPS) or systems with electric pumps: Some require a scan tool to run an on-board bleed/service routine; follow the factory procedure.
• Vehicles with speed-sensitive or variable-assist steering: Always consult the service manual; certain models mandate vacuum bleeding from the start.
• Cold vs. hot levels: Many reservoirs have “COLD” and “HOT” marks; perform final checks at operating temperature and re-verify the level.

Confirming your system type and any OEM-specific steps ensures the bleeding process is both safe and effective.

After bleeding: checks and troubleshooting

Once the system is bled, verify that symptoms are resolved and watch for signs of underlying faults that let air re-enter.

• Recheck fluid level after the first drive and the next day; minor drops can be normal as microbubbles purge.
• Inspect for dampness at hose connections, the rack/gear boots, and the pump shaft seal.
• If whining persists, look for suction-side leaks or restrictions; replace aged hoses or O-rings and consider the reservoir if it contains an internal filter.
• Persistent heavy steering may indicate a failing pump, binding steering joints, or rack issues rather than air.

Addressing these items helps ensure the fix lasts and prevents recurring noise or steering problems.

Summary

To bleed air from a hydraulic power steering system, safely raise the front end, fill with the specified fluid, turn the wheel slowly lock-to-lock with the engine off, then repeat at idle while maintaining fluid level. If aeration persists, vacuum-bleed the reservoir and inspect for suction-side leaks, worn belts, or a restricted reservoir. Systems with electric assist may require a scan-tool bleed or may not use fluid at all. Proper bleeding restores quiet, consistent steering and protects the pump and rack from premature wear.

How to get air out of a power steering pump?

To get air out of a power steering pump, slowly turn the steering wheel from full lock to full lock with the engine off, then start the engine and repeat the process while monitoring the fluid level, adding more fluid as needed. Ensure the front wheels are lifted off the ground to prevent unnecessary wear and make the steering easier. For stubborn cases, a vacuum pump can be used to draw air from the system. 
Method 1: Turning the Steering Wheel

1. Prepare the vehicle: Park on level ground and lift the front of the vehicle using a jack to keep the wheels off the ground. 
2. Check the fluid: Open the hood, locate the power steering fluid reservoir, remove the cap, and check the fluid level. Top it off to the “Full Cold” line with the correct fluid for your vehicle. 
3. Bleed the system (engine off): With the engine off, turn the steering wheel slowly from the full left to the full right position. 
4. Repeat: Stop at the center, check the fluid level, and add more fluid to keep new air from entering the hoses. Repeat this process 12 to 15 times. 
5. Start the engine: Start the engine. 
6. Bleed the system (engine running): Turn the steering wheel from full lock to full lock again, slowly. Check the fluid level and add more fluid as needed. Continue this until the fluid is no longer foamy or bubbly. 

This video shows how to bleed the power steering system by turning the steering wheel lock to lock: 1mWorld MechanicsYouTube · Mar 4, 2016
Method 2: Using a Vacuum Pump

1. Prepare for vacuum: Install a vacuum adapter into the power steering reservoir cap. You may need to drill a hole in the cap to fit a fitting for the vacuum pump. 
2. Apply vacuum: Attach a vacuum pump to the adapter. 
3. Start the engine: Start the engine and let it idle. 
4. Draw vacuum: Apply 20-25 inches of vacuum to the pump. You will hear the pump make noise as it pulls air from the system. 
5. Turn the steering wheel: While the vacuum is applied, turn the steering wheel from stop to stop about 10 times. 
6. Check fluid level: Turn off the engine and release the vacuum. Check the fluid level and add more if needed. 
7. Repeat if necessary: If the fluid is still bubbly, repeat the process, as air may still be trapped in the system. 

Tips for Success

• Use the correct fluid: Always use the power steering fluid recommended in your owner’s manual. 
• Don’t overfill: Keep the fluid level at the specified line to prevent new air from entering the system. 
• Be patient: It may take multiple cycles of turning the wheel or a combination of both methods to remove all the air. 

What happens if you don’t bleed your power steering system?

What happens if you don’t bleed power steering? If there’s air in your car’s power steering system, you’ll notice it becomes difficult to steer and your car may make a growling noise. Driving with air in the system can also cause the steering pump to fail.

Do you bleed a power steering pump with the cap on or off?

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. 

How to get air out of power steering without a vacuum pump?

You remove the lid of the fluid reservoir, top up the fluid, and turn the steering wheel from lock to lock a few times. This should remove the air from the system. The you top up the fluid again – if it needs it, and repeat the process until it doesn’t.