Ok, they replaced the F**ing master cylinder. It feels even worse now. When you push the pedal, it takes a longer distance for the brakes to engage, and then after that the pedal keeps going down. Is it possible that they f*ed things up, or do they not know how to bleed?

Vinuneuro:

A couple of questions and a few comments.

1) When they replaced the front brakes, did they overhaul or put kits in the calipers, or just put pads (or pads and rotors) in? If they didn't open the calipers up, I am not sure why bleeding would have been required in any case. It is possible, but not likely, IMO. If they did open the calipers up, then bleeding makes sense.

2) Think of the master cylinder as a pump that usually works on a very short portion of its stroke. It takes very little movement of the master cylinder piston to activate the brakes. Beyond the normal stroke is where the junk collects in the master cylinder bore, usually involving pitting caused by water in the system. If the piston in the master cylinder is moved to a zone that it doesn't normally work in, where there can be pitting, then the seals gets damaged and the master cylinder can leak internally (it bypass). That can create the soft pedal. A failed master cylinder after a brake job isn't common, but it isn't unusual either, particularly if the brake fluid wasn't changed regularly over the past few years. Also, pushing the calipers back in can stir things up in the master cylinder. If the master cylinder was healthy, not an issue. If there was any junk sitting in there, immediately after a brake job is when it will fail (other than the usual failure mode which is simply from old age, and hardened seals).

3) Improper bleeding with a pressure bleeder can also cause problems after a brake job, as hayaku notes.

4) $600 does not seem high to me for a master cylinder replacement. These cars are not cheap to fix. They wouldn't have used a jobber master cylinder, but rather a BMW original. Yes, aftermarket warranties will be getting more expensive as the cars age.

5) I would expect an aftermarket warranty to cover brake parts that aren't wear items. A master cylinder is a reasonable thing to cover. Pads and rotors aren't (they may be part of a maintenance plan, but that isn't warranty). Depends entirely on the fine print.

6) Warranty Direct may ask the dealer for the failed part. That is between the warranty insurance company and the dealer at this point. At the very least they would expect a service report. You really don't know that they ripped Warranty Direct off. If you want to pursue it, ask for a copy of the service report. That mean's the mechanic's report, not the invoice. They probably don't have to give it to you (you weren't the customer here, Warranty Direct was), but you are the type of owner who will want all the details. Nothing wrong with that.

7) It is possible that the new master cylinder still needs more bleeding (there are lots of places for air to be trapped). Yes, they should have got it all. I am not making excuses for them, but it can happen. If you aren't happy with the pedal firmness, take it back in. Compare it to another one on the lot. Don't necessarily be surprised that it feels different (new pads, new master cylinder), but it should feel acceptably firm.

8) If, after bleeding all of the brake circuits, the pedal does not hold but instead drops slowly (or quickly) to the floor, then you have a problem in the master cylinder. It can be intermittent. In that case, it doesn't sound like it is fixed yet.

Good luck. Let us know how it turns out.

You could also talk to warranty Direct and see if they would authorize you to take it somewhere else to have them inspect the work that was done. It could be in favor of Warranty Direct as well. If the original shop is incompetent, Warranty Direct is continually paying them money for work that is not required. If the second shop sees a problem with the work that was done by the original shop, Warranty Direct can take what actions it wants which may include them refusing to pay for the work that was done.

You might want to stress to Warranty Direct that it is an issue with the brake system, which means you may not be able to stop the vehicle. This is a safety issue that could cause serious injury or death to yourself and to others as well.

-It states that a brake pad kit was used, along with a new brake disc and sensor.

-Brake Fluid was changed this past spring.

Well, regardless of whether the brake work and MC change were done under warranties or not, BMW warranties labor and parts for 1yr/12k mi. This week the new tires will be mounted and it'l go to a BMW dealer for the alignment anyways. So I'm going to take the vehicle to a different dealer and ask them to look at this as well. The lack of pedal firmness is quite blatant.