DSC pump compatibility

[ClumUK]

Hi all,

I’ve been having a soft brake pedal saga that’s been going on for months with my 2010 35is.

My garage has checked the car out several times, done pressure bleeds and found no leaks, master cylinder seals are fine, checked the lines from end to end and they’re “bone dry”, however the issue keeps reappearing within a couple of weeks of a fluid change.
I even took the car to BMW recently and paid through the nose for diagnosis in the hope that I could finally resolve this issue, but their only suggestion was that it could be the DSC pump. I’ve never had any fault codes appear for this though.

So in a last ditch attempt I’ve been looking for a used DSC pump/module that my garage can fit just in case, but the majority that I can find available have a slightly different part number to what’s fitted in my car, although they visually appear to be the same.

My car:
3451 6797782-01
3452 6797781-01

0 265 236 378 / 3451 6768550-02

What I'd like to buy:
3451 6850890-01
3452 6850891-01

0 265 236 448 / 3451 6768550-02


I’m therefore wondering if anybody knows if these parts would be a compatible replacement? Or at the very least, would I be able to fit the newer pump to my old module and replace?

Thanks for any help!

[B21]

Your numbers don’t seem to tie up with what realoem says?

[flybobbie]

Just embarking on this saga.
Pedal gone soft but feels like i can hear the fluid running past at least say the rear master cylinder seals.
When i changed the rear fluid it was black.
Looked around for a seal kit, can't find one.
Replacement master cylinder nearly 400 quid, robbing b*******ds.
Waiting on a 40 quid 2nd hand servo and cylinder.

[flybobbie]

Well replaced the master cylinder and all good now.
I would venture down this route, try getting a 2nd hand cylinder fitted.
For reference my car has done 96k miles.

I only replaced fluid a few weeks ago but still came out dark.
So the seal was still disintegrating.

[ClumUK]

Glad yours is sorted now. It was BMW that checked the master cylinder seals and said mine was fine. I keep getting milky brake fluid, but not black. My garage is completely stumped...

Going off those part numbers above not matching, it's making me think I should be fine to fit any pump (with my original controller) and it will work. I'm hoping that fixes mine as I'm off to France with the car soon!

[ClumUK]

Well replaced the master cylinder and all good now.
I would venture down this route, try getting a 2nd hand cylinder fitted.
For reference my car has done 96k miles.

I only replaced fluid a few weeks ago but still came out dark.
So the seal was still disintegrating.

Do you know if all variants and years use the same master brake cylinder & servo? RealOEM suggests so, but I've seen some listings on eBay that say 2012 onwards and have different part numbers =/

Starting to think I'm not gonna be able to take the Zed abroad now

[B21]

Stop start versions had a different servo to others…

AFAIK all E89s use the same master cylinder..

[ClumUK]

Stop start versions had a different servo to others…

AFAIK all E89s use the same master cylinder..

Ah makes sense, thanks! Now I've taken a look at some pictures I can see the stop-start version appears to have a plug on the servo that mine doesn't.

And yes, I'm now questioning BMW's "diagnosis" that the master brake cylinder is fine... Getting so desperate I think I'm gonna have replaced the entire braking system once I'm done

[mcbutler]

Well replaced the master cylinder and all good now.
I would venture down this route, try getting a 2nd hand cylinder fitted.
For reference my car has done 96k miles.

I only replaced fluid a few weeks ago but still came out dark.
So the seal was still disintegrating.

Was that an OEM master cylinder? Seems way too expensive