Why would the power steering make noise even after fluid has been added?

Power steering noise

When the fluid is low and you add some, it may still need more after you run it for awhile. The reason is that as the pump pumps the fluid through the lines, this also normally pushes any air out the lines. Keep filling and checking after you start the car and turn the wheel from side to side all the way.
  • The bigger question is why do you need to add fluid? After you locate and fix that leak, you can address the whine. If it is a Ford, it may be somewhat normal. Like Drazi said, "It may be air trapped in the line." Or the pump may be damaged from running it dry, or there is bilge in the line, starving the pump. Let's assume you have kept up on the maintenance and have flushed the fluid when it was dirty. Let's also assume that the pump is not damaged and you have found and fixed any leaks. Try this: pull the fluid out of the reservior and add one bottle of Lucas brand power steering additive, and top with power steering fluid. I have found this stuff pretty good at resolving many power steering problems. I'm not a big supporter of "Snake Oil", but have had good luck with it.
  • If it's a Ford, it's because they use plastic parts in their casings, though most other car companies do the same. If that's not the case, then your pump is receiving too much stress from turning. Try lubing up the chassis and changing the fluid completely. It wouldn't hurt to check your lines either. Sometimes blockage can cause too much stress on the pump too.
  • First thing is why are you adding fluid. If it has a leak, then I would address that problem first. A pump will not bleed air out of the system if it is leaking. If everything seems to be okay and your pump still whines, then replace the pump, preferably with a new one from the dealer. The so-called rebuilt pumps that you can buy from places like Autozone, O'Reilly, etc. are cheaply rebuilt, especially if it's a Ford. They don't bleed out air properly, resulting in improper pump pressures. A good pump will bleed out almost immediately, with the turn of the wheel a few times. If it doesn't, then your pump will more than likely never completely bleed out. Buy a new pump from the dealer--it costs more, but if you're like me and don't like the noise, then it's worth it.
  • You probably have air trapped in the power steering fluid system. Bleed the air out by revving the engine to about 1500-2000 rpms and turning the steering wheel almost all the way from one side to the other a few times. This should bleed out the air and take care of your problem.
  • If the noise is similar to that of a dry bearing, then the problem is probably the power steering pump itself. If the noise you hear has a "click, click, click" to it when you make turns in your vehicle, then the problem is more-than-likely your CV joints. If the noise is screeching, check your belt for wear-and-tear and proper tension (see owner's manual), and the pulleys that the belt turns, including the air conditioning compressor motor and its clutch/pulley.

I just wanted to add another two cents about the topic of bleeding or burping the power steering system:

1. Know what type of power steering fluid is needed for your car. Some power steering pumps can use automatic transmission fluid, others have specific power steering fluid for each car, i.e. Honda requires and suggests that you use Honda's brand of power steering fluid (see owner's manual). Make sure you know, or the warranty from the dealership or from the parts store may be voided.

2. Before attaching the power steering belt, fill pump with required amount and type of fluid (see owner's manual), and then turn the pulley wheel by hand a few times. This helps cut down on dry turns before they can happen. If more power steering fluid is needed, fill accordingly.

3. Attach the power steering belt with proper amount of tension (see owner's manual).

4. Turn vehicle on and proceed to turn the steering wheel all the way right and left 3-4 times.

5. Turn the vehicle off, and examine that the belt tension is acceptable, and again check the level of fluid and fill accordingly.

6. Always, always check your owner's manual before performing any maintenance on your vehicle. An educated car owner is a safe car owner!

Another possibility

How long has the pump run without fluid? There could be damage inside to the cam and rotor (assuming it's a vane type pump), or to the plates, or it could be cavitating due to the ingress of air -- possibly why the fluid leaked out in the first place.

www.powerbrakeandsteering.co.za

I too experienced very loud whining noise from my 93 Ranger 3.0's power steering pump at idle, and even louder when turning the steering wheel even a little bit in either direction. I changed the fluid but there was no change in noise. I read in a Ranger forum that if you add some STP oil treatment (yes, STP OIL TREATMENT), not the whole can, it would help. I decided to give it a try and sure enough it has reduced the noise greatly. It didn't completely eliminate it but people no longer stare at my vehicle at red lights because of the noisy pump. That was embarrassing! Ford's pump must be partly to blame since the problem is so rampant among all their various models.

By the way, Mercury is supposed to begin being phased out (discontinued) beginning in 2010 and completely gone by 2012. Only Ford and Lincoln will remain. Just thought ya'll might want to know that since your Mercury's value will likely plummet as that kill-off nears. However, those of you who have a stiffy for Mercs may get a good deal on one before they are gone. I personally don't think they are "all that". Fords in general are pretty low market in build and longevity. I used to favor GM but switched to Honda products in the 90s, they are very long-lived. My latest is a Jaguar and I'm quite happy with it. Yes I know they were owned by Ford and now by Tata Motors but the design is all Jag.