Seeing foamy power steering fluid in your vehicle’s power steering fluid reservoir can be alarming. After all, healthy power steering fluid should be smooth and not frothy. Let’s look at what’s likely causing your vehicle’s power steering fluid to foam and what you can do about it.
Why Is My Power Steering Fluid Foamy?
Aeration is the main cause behind foaming power steering fluid.
You’ll know there’s air in your power steering if you hear the pump whining during steering maneuvers and/or feel jerky assist, usually in a parking lot.
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Pro Tip: Believe it or not, in some cases, the fluid can get aerated when there’s nothing wrong with the pump and there are no leaks. But there is a bit of evaporation that happens with power steering fluid sometimes, as peculiar as that might seem, and power steering fluid can sometimes get low when there are no leaks.
Air mixing into the fluid causes the fluid to foam. Here are the different ways air can enter the lines:
Worn Seals or O-Rings
If there are any worn seals or o-rings along the power steering fluid supply line on vehicles with a remote reservoir, the power steering fluid pump will draw air into the lines.
The power steering pressure lines won’t typically draw air because when the pump is working, the pressure in the lines is higher than atmospheric pressure.
But once that air enters the power steering fluid pump reservoir for whatever reason, the pump aerates the power steering fluid simply by running, which causes foaming.
Low Power Steering Fluid Level
The power steering fluid pump might pump air into the lines if your vehicle’s power steering fluid level is too low. Once the pump starts pumping air instead of fluid, it’ll lead to aeration and foaming.
Clogged Reservoir Screen
Faulty Power Steering Fluid Hoses
Air can also enter the power steering fluid system through holes in any of the hoses along the line supplying fluid to the pump, but not carrying fluid from the pump to the steering gear or brake hydroboost unit. If there’s a cracked, brittle, loose, or damaged hose anywhere, the air is likely getting sucked in and causing the foaming.
Improper Fluid
If your vehicle’s power steering fluid is foaming, it’s possible that your power steering fluid line isn’t holding only power steering fluid. It’s also possible that you filled your vehicle’s system with a non-compatible power steering fluid. Only use your vehicle’s manufacturer-recommended power steering fluid in its system, or you might damage the power steering fluid lines.
Foaming Power Steering Fluid Solutions
Before you figure out how to stop power steering fluid from foaming, you’ll need to track down what’s causing it to foam in the first place. If air’s getting in through worn seals, o-rings, or hoses, flush the system and replace those parts before refilling the system with new fluid.
You can also try to bleed the power steering system of air.
First, fill its reservoir until the “cold” mark. Raise your vehicle off the ground and turn your steering wheel fully in one direction until it locks.
Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.
Pro Tip: Raising the vehicle will prevent unnecessary stress on the front end steering parts.
Wait five seconds and then turn the steering wheel the opposite direction until it locks. Repeat this process and listen for the whining noise in the pump to subside. Check the power steering fluid levels periodically.
If 20 cycles of the wheel from stop to stop doesn’t remove the aeration, check the screen in the bottom of the reservoir. If the screen is clear, do the vacuum procedure shown in the following video. In rare cases the pump may need replacing.
This video is based on a GM TSB written to help technicians who are bleeding stubborn air from the power steering system. Caveat: this video uses engine vacuum rather than a handheld vacuum pump as suggested by GM.
Can You Drive With Foaming Power Steering Fluid?
The power steering system is in place to help you steer your vehicle more easily. While you can steer without a fully functioning power steering system, it will be more difficult. Problems with your vehicle’s power steering fluid can damage its power steering pump and steering gear. That’s why it’s best to avoid driving with foamy power steering fluid.
Power steering fluid is important for keeping your vehicle easy-to-maneuver. If you notice it foaming, it’s best to find the cause and flush the system as soon as you can. Now at least you know what causes might be behind this strange phenomenon.
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