Stiff power steering, the pump or ?

[Tonyfeb14]

My 2003 4.4 X5 power steering is starting to feel very sluggish/stiff. Just not as light as it should be. Fluid level is good. The alignment might be off, little more tire wear on outside edges, so will take care of that. All bushings and ball joints are good, with new control arms just installed. The steering was getting stiff before I replaced the ball joints. Does anyone know how to test if this is the power steering pump or the rack and pinion that’s is going bad? The pump looks straightforward to replace. The rack is a bigger job requiring supporting the engine while dropping the subframe, so not something I want to tackle if I can test first.

Thanks, and always, great information and insights on this forum.

[andrewwynn]

Is the ambient cold and does it get better after it warms up?

The steering is heavy on the x5, so just confirming it’s not you didn’t have your vitamins problem. Are you confident it’s getting firmer?

If ambient is cold find some snow to drive in and see how much easier it is to steer if it doesn’t change much it’s a confirmation of a problem. (It should be about twice as easy to steer on ice/snow)

[Tonyfeb14]

Vitamins are not the issue 😁. The steering is definitely getting slightly harder to turn. I have owned the car for 8 years so it has been gradual, but definitely harder than my other vehicles. I am getting the alignment checked next week. The question, how can you tell if the pump output is low or if the rack needs replacement when this happens? Turning it on ice of course will be less resistance so not sure what that proves?

[Ragnarok]

I don't have an answer, I just wanted to say that I have experienced this exact same problem with my '03 4.4i. It was intermittent; it happened very occasionally after I first bought it sometime over a year ago and over time it happened less and less and nowadays it basically never happens at all. There were no strange noises, no leaks of PS fluid, and no visible damage/issues with any steering related components when I inspected them...I searched this forum and others for solutions for a while, but since it went away on its own I let it go....

[andrewwynn]

That could be stunt helpful feedback. That leans toward something like debris in the fluid or contaminated fluid. Before replacing hardware, maybe a suction replace of the fluid?

The drive on ice concept is to help get a feel for where it’s getting stiff; when fighting the massive grip of the tires it’s hard to tell, but when you remove that from the equation you can tell if the steering is equally stiff lock to lock, harder left, harder right, etc. it will help if somebody else turns the wheels and you can make observations under the hood.

[guntherrex]

on my outback a similar issue is created by a small airleak in the suction side of the system creating air bubbles which in turn mess up the operation of the pump

[andrewwynn]

That makes a lot of sense. Would not take much air to mess up hydraulic power. Did you see artifacts like froth in the reservoir?


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[SlickGT1]

Then there is always that universal joint on the steering shaft.

[andrewwynn]

That will gives you slack shouldn’t make it stiff to turn (unless it was rusted so it didn’t bend)


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[X5only]

I would put the front on jack stands, drain, refill, and bleed the power steering fluid per https://www.newtis.info/tisv2/a/en/e...g-unit/DsV56Jq.

There's also that Lubrizol 6178 - Pelican has it - that you may want to try if you're up to it. Here's a thread you may want to go through.

https://xoutpost.com/bmw-sav-forums/...g-fluid-4.html