How to Check and Add Power Steering Fluid

Co-authored by Hovig Manouchekian

Most cars except some electric and hybrid vehicles have a hydraulic power-steering system that enables the driver to turn the steering wheel without a great deal of effort. The power-steering system consists of several items: a rack and pinion connected to the front wheels; a piston inside the rack and pinion, which is moved by pressurized fluid from the power-steering pump that helps to turn the wheels; and a cylinder containing fluid mounted on the pump or remotely mounted for easier access. (If there isn't enough fluid, steering becomes more difficult and either the pump or rack and pinion could be damaged without fluid to cushion them.) Therefore, it's important to check power-steering fluid levels on a regular basis and add fluid when necessary.

Steps

1
Look for the reservoir cylinder. If you're having difficulty turning the steering wheel or a high-pitched whining noise issues from the steering wheel when you turn it, chances are your power-steering fluid is low. The power-steering fluid can be found in a cylindrical reservoir near the power steering pump or remotely located with hoses from the pump, and should be clearly labeled. The cylinder may be made of either plastic or metal.
- If you can't find the cylinder, consult your owner's manual for the location. While the power-steering reservoir is usually located in the same space in most cars, newer vehicles may place them elsewhere for economy or space.
- If the steering wheel is locked, you can check the key. It may wear out.^{[1]
  X
  Expert Source
  
  Hovig Manouchekian
  Auto Repair & Design Specialist
  Expert Interview. 23 February 2021.}
- Check the tumbler, it wears out with regular usage.^{[2]
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  Expert Source
  
  Hovig Manouchekian
  Auto Repair & Design Specialist
  Expert Interview. 23 February 2021.}
- Also check that the neutral safety switch or the shift linkage is in the proper position.^{[3]
  X
  Expert Source
  
  Hovig Manouchekian
  Auto Repair & Design Specialist
  Expert Interview. 23 February 2021.}
2
Check the level of the power-steering fluid. If the reservoir cylinder is made of translucent plastic, you may be able to see the fluid level inside the cylinder. If the reservoir cylinder is made of metal, or if the plastic is not sufficiently transparent, you'll check the fluid level with a dipstick, which is usually attached to the cap.
- On some cars, the power-steering fluid level can only be checked accurately after the engine has run for a brief period, and sometimes you must also turn the steering wheel in either direction several times while the car idles.
- On other cars, there are gradations on the dipstick or cylinder for both a "hot" level, after the engine has been running, and a "cold" level, after the engine has been off for a period of time. On still other cars, there may be "Min" and "Max" lines for acceptable fluid levels. Be sure to compare the power-steering fluid level against the correct mark.
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3
Examine how much of the dipstick is covered by power-steering fluid. If you are using a dipstick to test the power-steering fluid level, first wipe off any excess fluid from the dipstick when you first take it out of the cylinder, then reinsert it as far down as it will go and pull it out again.
4
Examine the color of the power-steering fluid. Good power-steering fluid should be clear, amber or pinkish in color.
- If the power-steering fluid is brown or black, it has been contaminated with bits of rubber from connecting hoses, seals or O-rings. In this case, the car should be taken to a mechanic to see if any of the power-steering system parts need to be replaced, along with the fluid.
- The power-steering fluid may look darker than it actually is. If you have any doubts, look at the color of the power-steering fluid stain on the rag or paper towel you wiped your dipstick off with. If the stain is the color the fluid is supposed to be, your fluid is not contaminated.
5
Add power-steering fluid as needed to the correct fill level. If your car has gradations on the cylinder, you can add the fluid steadily until you reach the correct "hot" or "cold" fill level; if you checked the level with a dipstick, add the fluid incrementally to avoid overfilling the reservoir.
- Be sure to use only the power-steering fluid that is recommended for your car, as it will be the correct viscosity (thickness) for your car's power-steering system.
- The manufacture does not recommend using transmission fluid in place of power steering fluid. There are too many different types of fluid, and if the wrong fluid is used, it may cause failure of power steering and its seals.
- Be careful not to overfill your power-steering unit with fluid. It's probably better to under fill your unit than overfill it. That's because power-steering fluid expands as it heats up and works its magic. If you fill your unit all the way to the top and then try to drive your car, the expanded pressure could begin to cause problems and might necessitate expensive repairs.
6
Replace the cylinder cap. Depending on the make of car, you may have to push or screw the cap into place. Be sure it's firmly attached before you close the hood.

Warnings

Power-steering fluid should also be replaced at the intervals called for in the car's owner's manual. Heat from the engine and surrounding environment will, over time, reduce the fluid's ability to do its job and cause wear and tear on the power-steering system components. Replacing the fluid is cheaper than having to replace either the power-steering pump or the rack and pinion.

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Not all cars take "generic" power steering fluid; search online or your owner's manual for the specifications on the proper fluid for your car.

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