change the brake master

Hello, I'm Danny.

Here is the information you requested. Here are a few tutorials for you to view on how to replace a brake master cylinder and how to bleed the system after the repair has been made:

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

Since you are installing a new brake master cylinder it would be best to bench bleed the unit before installation to remove air from the new unit prior to installation on the vehicle. Here is a YouTube tutorial from our site showing how to do so:

https://youtu.be/WDxvEQrMkBg

I've attached picture steps below on how to replace the brake master cylinder and bleed the system on your vehicle. Hope this helps and thanks for using 2CarPros.

How do I go about replacing the brake master cylinder kit on my BMW 325I.1990 with 230 000 km on the clock.

assuming you have the replacement part already in hand, remove the fluid reservoir, then the brake lines, then the two bolts holding the master cylinder to the booster. inspect inside the booster for brake fluid. if fluid is present replace the booster. reinstall new part and bleed system