Hay,

Does anyone have an experience of this type of problem ?, just changed the breake fluid at BMW but the same problem persists. No leaks and the breaks work fine with normal pedal pressure. The pressure seems to build up more at high revs.
Main break cylinder internal leak ??:eek:

// Fredrik

..or maybe your Brake Pressure Accumulator (Brake Bomb) may be going out..

Agreed!

A good test would be to pump your brakes without the key in ignition. It should take between 20~22 pumps to get real hard. If it takes more or less it is the issue with the accumulator or the connecting lines.

Click Here for DIY instructions. (http://www.e31faq.com/attachments/att125.pdf)

Thanks for the reply,
This one is tricky, i will have a go at the main break cylinder. The break bomb is ok and i have no alarms or pressure fail indications. I forget to write that the car has been standing for 2 years and the brake fluid was 4 years old. Yes i know .....

// Fredrik

brake bomb will not throw a code or alarm, it just fails. What you described is very accurate for that failure. It may not have totally failed, but it will...

..or maybe your Brake Pressure Accumulator (Brake Bomb) may be going out..


Yes I had to change my brake booster aka brake pressure accumulator, I had the same signs as you are as well. I told the mechanic to flush my brakes, bleed them, and in the end none of that worked out until I change the booster.

booster and accumulator (brake bomb) are NOT the same thing. The Booster is mounted to the firewall in front of the master cylinder, the bomb is mounted in front of the left front wheel behind the front bumper.

Thanks !! Ok, i will start with the main cylinder, then the booster then the bomb. Weekend booked.
I still think it's the 2'nd pressure cirquit that has a n internal leak inside the main cylinder.

I would start with the bomb, the booster, the master cylinder in that order, but anyway Good Luck!

I will file a report when this is fixed. O&O Fredddy Sweden

Changed the bomb today. No obvious change. Only thing now is that the new bomb discharges on about 10 pedals ???. Old one about 20. Can heare the flow regulator charge the bomb on every 3'rd pedal break.

I would start with the bomb, the booster, the master cylinder in that order, but anyway Good Luck!

Hay , passed MIT today ( Swedish ) car test. 100 % ok, nothing. Anyway, i still think the break acts strange if used like "panik". The MIT man just slowly pressed the pedal and this is not a problem.
Can you press your pedal down to the "ground" at standstill with motor running.
// Fredrik

By the way, my CSI will be for sale later this year. 12/-96 87000 km second last one made. Black on Black. I had it for 6 years without problem.

You will have no shortage of potential buyers!