2004 4.4i Brake Issue

[wydra]

Hey guys,

I thought I’d check to see if anyone else has noticed this.
I recently replaced my front rotors with Slotted rotors and DBA pads front and rear.
Before I did the rotor and pad swap i noticed the brakes were not stopping the car at very slow speeds and put it down to the pads being so low.

This is the best i can describe the problem:
When stopped at the lights the brakes are only JUST holding the car from rolling forward. If you keep your foot on the brake and rev the car (while still in D) it will slip forward. In the past it used to hold tight.
It feels like the pedal is getting very firm and can’t be pressed any more. If you drop the car into neutral and rev the car while still pressing the brake you feel the brake pedal go softer and more braking force applied (with the same foot pressure)

It’s almost like the brake booster is leaking or not working correctly.

When at speed the brakes work fine, emergency stop from 100mph is fine with the ABS working perfect and bringing the car to a stop.
It’s just when you are almost stopped it appears and the brake pedal feels too hard.

I don’t want to just jump in and replace the brake booster as they are rather $$$ and not the simplest things to replace, especially if it doesn’t fix the issue.

Cheers,
Dale

[wydra]

I am currently checking with BMW to see if this is a re-call item.
Has anyone else see this issue?

[Turks4.4]

Probably just didnt bleed your brakes properly.

[wydra]

I wish it was something simple like this.
I have totally bled the system with new fluid and it is still like this.

The pedal is firm when pressed, almost the opposite of when you need to bleed your brakes.

[JCL]

Sounds like it could be a problem with the brake booster/servo, or the vacuum supply to it.

From the old days (not specific to BMW vehicles): Check it by confirming pedal position with the engine stopped and running.

First, turn the engine off. Pump the brake pedal until all the vacuum is gone. It will be hard. Start the engine. The pedal should drop due to the vacuum assist.

Start the engine and run it for a few minutes. Turn it off. Press the pedal several times. The pedal should come up each time; if so, the booster doesn't have a leak.

If you are checking for a vacuum leak, it is like tracking down any other vacuum leak, it will affect the idle. There will be a check valve in the vacuum line to the booster to check as well.

There are more specific tests for proper booster operation, but the above steps should point you in the right direction.

Good luck.

[wydra]

I know this thread is pretty old now but i thought id give anyone who cares an update.

BMW advised this was not a recall item for the e53 so it was not covered.
The brake servo / booster was about $1800 from an BWM dealer in Australia.
There was a wrecker on the east cost of Australia which would sell me a second hand unit for about $1000 delivered to Perth.
I managed to source a used part from the US for under $200 delivered.

I managed to remove my brake servo, reinstall the new unit, bleed all the brakes with new fluid and have everything back together again within a day. All up it cost me under $200 for the servo and under $50 for dot 5 fluid.

The brakes are now back to how they used to be and stopping strong