E92 M3 Brake Fluid Flush

Brake fluid flush how-to for the E92 M3. Do all work at your own risk.

Requires:

If you’ve ever done this job before on any car, the process is identical. Get the car up on stands & pop the hood. The master cylinder is hidden via a black plastic panel held on by 3 8mm screws. Remove those and twist the panel around to reveal the master cylinder.

There is another black plastic panel that simply pops off if you pull upwards, shown below. Without removing this, it is difficult to tell where the brake fluid level actually is.

I actually had a brake pressure bleeder with a fitting for my Mini Cooper, and the fitment was exactly the same on the M3 – makes sense, given they are built by the same company in the same era. I simply screwed on the attachment and pressurized the system.

Without this, you can use a friend to push the brake pedal up and down. The order I went in was:

  • Passenger rear
  • Driver rear
  • Passenger front
  • Driver front

Typically you want to go furthest to closest away from the master cylinder. The rears are held on by 9mm valves. They are covered by rubber caps, which also hold the brake pad wear sensor wires, save for the passenger rear. Simply remove the cap, crack open slightly, and use a wrench to open and close the valves. The rubber cap can get in the way of the wrench, so watch for that. If you don’t have a pressure bleeder, the order should be:

  • Brake pedal down
  • Open the valve
  • Close the valve
  • Brake pedal up
  • Repeat
  • Check the brake fluid level every so often

Even with a pressure bleeder, I like to have a friend help at least a few pushes to get more fluid out and can sometimes release trapped air the pressure bleeder doesn’t get. Straight forward job here. Once done on each side, tighten the bleeder – not very tight at all, close the cap, and that’s it.

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