BMW F11 N57 530D (2011) Power Steering Leak From Cap and Foaming

Dear Experts,

My German is not so good so hopefully you guys don't mind that I post something in English.

Driving a BMW F11 2010 RWD. Fluid has been leaking a bit out of the cap of the oil reservoir of the hydraulic pump. In addition there is foam in the reservoir when the car runs but this is something which I already have a longer period (couple of years). There is enough fluid in the reservoir if I read it at the 20c line.

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The pump in my car is only used for the active roll bar system (dynamic drive). The shocks have there own closed system and the power steering uses an electric system with an additional battery in the back.

There are no fault codes of the system using ISTA. Furthermore no errors when I started the startup procedure run on it using ISTA.

Is there anybody who recently fixed this problem recently? Not sure where to start from here:

1) Replace reservoir and cap (32416782942)?

2) Replace the pump (32416850591)?

3) There is a leakage on the joint of the active rollbar on the front which is there already for a long time. Not sure whether this is causing the problem. Replace this? (37116778089)

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4) Just accept the problem for now and monitor it closely because the system is only used for the active roll bar system and maybe top it up with new fluid if it is getting low?

5) Something else?


Thanks in advance!

Happy new year!

In addition I was thinking to disconnect the fluid level sensor and see whether I wil get an error message. I suspect it will if I read TIS "

On the oil-level switch, short circuit or line disconnection cannot be detected. A line disconnection is interpreted as oil loss. A short circuit is not detected."

If a message is triggered at least I know that I can drive further safely and I will get a message when the fluid is too low.

Furthermore I can tilt the reservoir and see if it leaks. I suppose it shouldn't if the cap is sealing properly?

Anybody with the same problem recently or ideas where to start?

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Thanks for all the reponses. The leak on the front sway bar is there already for a long time. And bubbles are also in the reservoir for a long time.

Just thinking. Can the internal filter of the reservoir be clogged where there is getting too much in the reservoir because the feeding line to the powersteering pump doesn't have enough free flowing capacity because and thereby overflows? Same as this youtube post:

Zitat von MunichMark

Well, I guess the main question is… is there really a Filter in there ? Didn‘t see one….

Was a nice Video but he forgot to state if this actually fixed his problem… assume so ?

It's stated in the highlighted text from TIS.



"The oil reservoir contains an oil filter and an oil-level switch with float. In contrast to the oil-level switch, the oil filter cannot be replaced separately."



Not sure of course this is really the case? Maybe somebody else knows?

Seems to be fixed in this thread but different car: https://www.bimmerfest.com/thr…om-reservoir-cap.1194553/ but different car X5 and oil reservoir.

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Decoupled today the sensor and indeed it triggers instantly a fault code. This makes it somehow save to drive knowing that a fault code wil be triggered if the fluid level is getting too low. Space was to limited to tilt the reservoir far enough to see whether it is leaking from the cap under an angle.

For now I'm gonna monitor it and see whether the level is gonna drop in the coming days. Will keep you guys up to date. Sincerely.