How to Bleed the Power Steering System

Updated on February 27, 2020
Dan Ferrell profile image

Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.

When bleeding the power steering system, check for leaks if necessary.
When bleeding the power steering system, check for leaks if necessary. | Source

Why bleed the power steering system?

Maybe turning the steering wheel has become noisy, or parallel parking is harder. These are potential signs of air trapped in the power steering system.

Signs of Trapped Air in the Steering System

  • You hear a whine in the steering pump.
  • Bubbles appear in the reservoir fluid.
  • Reservoir fluid is low and foamy.
  • The steering wheel is hard to turn.
  • The steering system is leaking.
  • You hear a grunt or growling noise at low speeds when turning.
  • The steering wheel moans when it turns all the way to the left or right.
  • You hear a buzzing sound when turning the steering wheel.
  • The steering system makes a clunking noise during operation.

Air can find its way into the system in different ways:

  • because of a damaged hose, fitting, seal or component
  • because of a loose connection
  • after you've replaced a system component
  • after you have disconnected and reconnected a hose

The following sections help you check for trapped air and, if necessary, bleed the system. You'll find more than one method you can apply, depending on your particular model. So it's a good idea to check your car owner's manual or vehicle repair manual for the recommended procedure for your particular model.

To get a copy of the repair manual, you can buy an aftermarket, inexpensive one from Amazon. Haynes manuals come with many maintenance, parts replacement, and troubleshooting procedures, along with images and specifications, to help you do any of these projects at home. So you'll recoup your small investment soon.

Index
1. Checking the Steering System for Trapped Air
2. General Steering System Bleeding Procedure
3. Using a Power Steering Bleeder kit
4. Bleeding a GM or Honda Power Steering System
5. After Bleeding the Steering System
6. Staying Safe on the Road
Add only the power steering fluid recommended by your car manufacturer for your specific application.
Add only the power steering fluid recommended by your car manufacturer for your specific application. | Source

1. Checking the Steering System for Trapped Air

Probably you are not sure whether the steering system in your vehicle has air in it. Here are a couple of simple tests you can apply at home to check the system for air.

When fluid in the reservoir is low:

Top off the fluid in the reservoir to the Cold Full level. Consult your car owner's manual or vehicle repair manual for the correct type of steering fluid for your particular model.

  • If normal operation resumes without noises or hard steering, then everything is OK.
  • If fluid level drops again, there's a leak in the system you need to repair.
  • If fluid level is stable but noise or hard steering remains, go on to the next test.

Consult your car owner's manual or vehicle repair manual, if necessary, to make sure you are checking fluid level properly in your particular model. On some models, you need to check fluid level at operating temperature.

Searching for trapped air in the steering system:

If the previous procedure didn't solve the problem, or you suspect air has entered the system, do this test.

  1. Bring the engine up to operating temperature. You can let the engine idle for about 20 minutes or take it to the highway for a 20 minute ride and come back.

  2. Back at home, let the engine running and turn the wheel about 15 times from left to right and right to left without hitting the stops or locks.

  3. Shut off the engine and open the hood.

  4. Inspect the fluid in the reservoir.

    • If the fluid looks foamy or you see bubbles in it, there's air in the system and you need to bleed it.
    • If you still are not sure, you can go ahead and bleed the system anyway. It'll take you only a few minutes.

If you have decided to bleed the system, make sure to have the vehicle repair manual for your particular vehicle or make sure which method is the best for your application.

Which Bleeding Method Should You Use?

Make sure to use the correct bleeding method for your vehicle. Although there's a general procedure to bleed the system, some car manufactures recommend a different method to prevent system damage. Check your car owner's manual or vehicle repair manual.

A common and simple bleeding method requires turning the steering wheel from lock to lock.
A common and simple bleeding method requires turning the steering wheel from lock to lock. | Source

2. General Steering System Bleeding Procedure

The following is a general procedure to purge air from the power steering system.

However, some manufacturers provide their own instructions or recommend using a vacuum pump for this procedure, especially on late model vehicles. Check the following section to use a special bleeder kit for this purpose. If necessary, consult your car owner's manual or vehicle repair manual.

  1. Park in a safe place on level ground. Make sure the engine is cool.

  2. Pop the hood open and check the steering fluid in the reservoir.

  3. Add steering fluid, if necessary, to bring it to Full Cold level.

    • Only use the steering fluid recommended by your car manufacturer. Consult your car owner's manual or vehicle repair manual.
  4. Raise the wheels off the ground using a floor jack and secure the vehicle with a couple of jack stands.

  5. Start the engine.

  6. Slowly turn the steering wheel from left to right and right to left ten times, without hitting the stops or locks to prevent seal damage. This step will force air into the reservoir and out of the system.

  7. Have an assistant monitor fluid level. Don't allow the reservoir to become empty.

  8. Check the fluid level. Add fluid, if necessary.

  9. Repeat steps 6 and 7 until fluid level remains steady and you see no more bubbles.

  10. Shut off the engine.

If the manual method doesn't seem to get all the air out of the system (you still see bubbles in the reservoir fluid), you'll need to use a vacuum pump to bleed the system. Also, if you have a late vehicle model, use a vacuum pump to bleed the system. Go on to the next section.

The following video gives you a visual guide about the manual bleeding system.

You can use a hand held vacuum pump to bleed the steering system, especially on late model vehicles.
You can use a hand held vacuum pump to bleed the steering system, especially on late model vehicles. | Source

3. Using a Power Steering Bleeder kit

This is the recommended method to bleed a power steering system in a late model vehicle, but you can use it on other vehicle models as well.

Using a vacuum pump pulls any air pockets in the system to the surface of the fluid in the reservoir, and prevents any damage to seals that may be caused by turning the steering wheel from lock to lock several times using the regular purging method.

Besides, using a power steering system bleeder kit can greatly speed up the procedure.

For this task, you'll need a hand-held vacuum pump and a bleeder kit. Some auto parts stores may lend you a hand-held vacuum pump and, possibly, a bleeder kit for the job.

  1. Park your car in a safe place on level ground. Make sure the engine is cool.

  2. Pop the hood open.

  3. Wipe clean the reservoir cap of the steering system.

  4. Remove the cap.

  5. Install the bleeder kit adapter to the reservoir instead of the cap.

  6. Connect the hand-held vacuum pump to the bleeder kit adapter.

  7. Set the parking brake and the transmission to Park (automatic) or Neutral (manual).

  8. Start the engine.

  9. Apply 20 in.-Hg of vacuum.

  10. Wait about 5 minutes to see if the vacuum holds; you may see the needle on the vacuum gauge drop a bit because of the air inside; but, if the needle starts dropping too much, most likely there's a leak in the system that is introducing air into the system. Consult your vehicle repair manual, if necessary.

  11. If your vehicle comes with hydro-boost system, depress the brake pedal two times.

  12. Slowly turn the steering wheel from left to right and right to left ten times without hitting the stops or locks.

  13. Turn the wheels to the center position.

  14. Shut off the engine.

  15. Release the vacuum, remove the bleeder kit adapter from the reservoir.

  16. If you see foam or bubbles on the fluid surface, wait a few minutes for the bubbles to disappear. Then add fluid to the reservoir as necessary.

    • Only use the recommended steering fluid for your application. Consult your car owner's manual or vehicle repair manual.
  17. Install the bleeder kit adapter and connect the hand-held vacuum pump to the adapter.

  18. Start the engine.

  19. Apply 20 in.-Hg of vacuum.

  20. If your vehicle comes with hydro-boost system, depress the brake pedal two times.

  21. Shut off the engine.

  22. Release the vacuum, remove the bleeder kit adapter from the reservoir.

  23. Add fluid to the reservoir as necessary.

  24. Reinstall the reservoir cap.

After the bleeding procedure, make an overall inspection of the system looking for potential leaks.

Honda and other vehicle models may require a special bleeding procedure recommended by its manufacturer.
Honda and other vehicle models may require a special bleeding procedure recommended by its manufacturer. | Source

4. Bleeding a GM or Honda Power Steering System

To bleed the power steering system, General Motors recommends a specific procedure. In general, the major difference is that you need to keep the engine off as you bleed the system. This will prevent metal components in the pump from coming directly in contact with the presence of air pockets that may damage the pump.

Bleed the steering system following these steps:

  1. Park in a safe place. Make sure the engine is cool.

  2. Turn the steering steel wheel all the way to the left (GM) or right (HONDA).

  3. Open the hood and check the power steering fluid level. Add fluid as necessary so that it's up to the Cold Full level; use the recommended type of fluid for your particular model. Check the owner's manual or vehicle repair manual.

  4. Raise the front wheels using a floor jack and secure the vehicle with a couple of jack stands and choke the rear wheels.

  5. Slowly and smoothly, turn the steering wheel all the way to the right and left, only tapping the stop or lock, at least 20 times.

    • If your steering system has a long return line or a fluid cooler, turn the steering wheel 40 times fully left and right.
    • Have an assistant monitor fluid level. Wipe any spilled fluid that occurs during this step and maintain fluid at the Cold Full level.
    • Fluid level should drop slightly as air is purged from the system. If fluid level doesn't drop, there could be a restriction within the reservoir or steering pump, probably an air bubble. If cycling the steering wheel left and right doesn't remove this bubble, try using a hand-held vacuum and steering-system bleeder kit. Check the previous section.
    • If the steering fluid appears milky or tan, or bubbles appear in the steering fluid during this step, stop and check for a loose connection or fitting, bad seal, or bad hose or component that might be introducing air into the system.

On GM Models

  • Start and idle the engine. Add fluid to the reservoir to bring it up to the proper level.

  • Allow the engine to idle for about two minutes while turning the steering wheel left and right.

  • Then verify the following conditions:

    • Turning the wheel should feel smooth.
    • Fluid level should be steady without bubbles or foam or a discolored appearance; otherwise, shut off the engine and check the hydraulic system for a component leaking air into the system. Especially, check for worn or damaged seals and loose clamps securing hoses to their fittings.
    • You should not hear any abnormal noise coming from the steering system noise; otherwise, diagnose the system; a pump groan or whine may come from a hose touching the engine, frame or a body panel, or a bad pump.
  • Turn off the engine.

On Honda Models

  • Disable the fuel system to prevent the engine from starting. One way to do this is by removing the fuel pump fuse. If necessary, consult your vehicle repair manual.

    • Crank the engine for about 5 to 10 seconds, while an assistant monitors the fluid in the reservoir.
    • If fluid level drops in the reservoir, there's still air trapped in the system that needs to be purged. Repeat the bleeding procedure, if necessary.
    • If fluid foams, allow air to purge through the reservoir for at least 10 minutes and crank the engine again.
    • WARNING: Always allow at least 5 minutes or more between cranks to prevent damage to the starter motor.
    • If fluid level remains steady and no bubbles or foam appear while cranking the engine, the system has been bled.
  • Replace the fuel pump fuse.

  • Start the engine.

  • Make sure the steering fluid is stable and no bubbles or foam appears; otherwise, you may have a loose hose, fitting or bad seal or component allowing air back into the system. If necessary, check your vehicle repair manual.

  • Replace the reservoir cap and shut off the engine.

  • Center the wheels and lower the front wheels to the ground.

  • Start and idle the engine.

  • Allow the engine to idle for about two minutes while turning the steering wheel left and right. Only tap the steering wheel against the lock.

  • Verify the following conditions:

    • Turning the wheel should feel smooth.
    • Fluid level should be steady without bubbles or foam or a discolored appearance; otherwise, shut off the engine and check the hydraulic system for a component leaking air into the system. Especially, check for worn or damaged seals and loose clamps securing hoses to their fittings.
    • You should not hear any abnormal steering system noise; otherwise, diagnose the system; a pump groan or whine may come from a hose touching the engine, frame or a body panel, or a bad pump.
  • Turn off the engine.

Of course, always check the proper procedure for your particular vehicle make and model. Consult your car owner's manual or vehicle repair manual.

Trapped air in the steering system can hinder your ability to control the vehicle.
Trapped air in the steering system can hinder your ability to control the vehicle. | Source

5. After Bleeding the Steering System

Once you have successfully bled the power steering system, you want to make sure there are no other problems you are not aware of, and make sure you've fixed the issue.

Do the following system checks during the following days:

  • Make sure the reservoir fluid has no bubbles or foam.
  • There should be no noise operating the steering wheel.
  • Power assist should be smooth.
  • Make sure the reservoir fluid maintains the proper level.

If fluid level drops or bubbles appear, check for a loose connection or leak in the system.

After replacing power steering system components, system bleeding is necessary to prevent poor vehicle control, expensive repairs, and road accidents.
After replacing power steering system components, system bleeding is necessary to prevent poor vehicle control, expensive repairs, and road accidents. | Source

6. Staying Safe on the Road

Air creeping up into the power steering system is not uncommon. But you want to purge and, if necessary, fix any issues that led to the problem as soon as possible.

Trapped air in the steering system can cause:

  • system noise
  • unsteady steering
  • damage to system components

So bleeding the system will not only remove trapped air from lines, gearbox and pump, but prevent expensive repairs and a potential road accident because of poor vehicle control.

Check, diagnose and, if necessary, repair steering system issues as soon as they appear.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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    © 2020 Dan Ferrell

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