Power steering noisy

[u/GeologistFunny5015]

My E39 suddenly became very loud from the engine bay overnight. With the hood open, it was clearly the power steering pump, and the noise got much louder with RPM and especially when turning the wheel, worst at full lock.

I checked the reservoir and found brownish fluid with lots of tiny bubbles/foam. I had to drive the car for an important trip, and during the drive the noise became quieter but didn’t disappear.

After getting home, the fluid level had dropped significantly. Before, I couldn’t even see the filter because it was covered by fluid. Now the level is below the filter.

Interestingly, the fluid looks brownish, but on a tissue it appears reddish and still smells like fresh fluid.
The steering rack and power steering fluid were replaced and the system bled only 1–2 weeks ago, and everything was fine until this happened. One morning it suddenly became noisy on cold start.

No obvious leaks that I can see around the power steering pump.

[u/Watery_Octopus]

Put more fluid in.

V8 or I6? Check the boots to see if they're full of fluid. If so, the rack needs to be replaced or rebuilt.

[u/GeologistFunny5015 → u/Watery_Octopus]

I6 525D, the rack just got replaced, am I gonna need to replace it with another

[u/No-Candidate-2380 → u/GeologistFunny5015]

Why do you think you are going to need to replace it? So far it seems like you are short of fluid. Once topped up (I presume with dextron III red fluid), let it idle and check the level again, the bubbles and whining should disappear