2007 M45 Brake problem

[Jarg1]

A few days ago I started having a problem with starting the car. At first I thought it was a battery issue, but eventually determined the problem was with the brakes. I was having a hard time pressing the brake pedal enough to start. The problem has worsened. I can get the car to start, but the brakes will not release. If I pull the vacuum hose to the Brake booster, they will release. Any ideas what is going on?

Thanks,

[EdBwoy]

Hello Jarg. Welcome to NICOclub. and the M forum.

Clarify this for me. These days you can push the pedal far enough to get the car to start but the brakes won't release? Are you saying that the brake pedal will not come back up, or it comes back up but the car still won't move because the pads are grabbing?

If disconnecting the vac hose gets you going, then it's looking like a bad booster to me.
A master cylinder issue seems to be more likely to be evidenced by a squishy pedal. Example - post6756577.html?hilit=master%20cylinder#p6756577

[Jarg1]

Thanks for the reply.

Once I realized that I had to press the brake pedal harder, I have no problem starting the car. The pedal does come up after starting but remains very firm. I'm wondering if there is a valve in the booster system that might be misbehaving?

Hello Jarg. Welcome to NICOclub. and the M forum.

Clarify this for me. These days you can push the pedal far enough to get the car to start but the brakes won't release? Are you saying that the brake pedal will not come back up, or it comes back up but the car still won't move because the pads are grabbing?

If disconnecting the vac hose gets you going, then it's looking like a bad booster to me.
A master cylinder issue seems to be more likely to be evidenced by a squishy pedal. Example - post6756577.html?hilit=master%20cylinder#p6756577

[pedsemdoc]

Bad booster, vacuum leak or stuck caliper?