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Discussion Starter · #1 · (Edited)
I took my '03 M5 with 27K miles on it in for some routine maintenance about 3 weeks ago. Had them do an oil change, coolant, and brake flush. Got the car back and on the drive home, I didn't notice anything wrong. But, the next morning I took the car out to drive (a somewhat rare event...) as the weather was perfect and noticed right away that there was a heck of a lot of travel in the brakes and they were very soft. I drove it, again, the next day on about a 2 hour round trip drive (went sky diving for the first time and the Bea5t had to be part of that trip!) and the brakes never stiffened up.

So, I finally got the car back into the dealer, assuming that they just needed to bleed the brake lines better or something along those lines. Well, they just called and said that they had bled them a couple of times, including all the lines individually, and nothing is leaking and there are no fault codes or anything else. So, they're saying that they think they need to order and replace the master cylinder and booster (I believe) for what amounts to some serious coin!

Anyone ever experience anything similar or have any ideas or advice?

TIA!
 

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Discussion Starter · #2 ·
And, yes, I did search before posting and couldn't find anything that seemed to give me what I need to try to determine the next best steps.

Additional info: If I pumps the brakes, pressure builds and the pedal gets stiffer, but it then seems to 'bleed' right out . . .


Thx.
 

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can't help you here but I would talk to the service manager asap as the mechanic obviously did something wrong with your car. You should not have to pay for their mistakes. I wonder if somewhere in the brake system the mechanic has introduced a small crack in it to allow air to enter?
 

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Find another dealer or better yet a reputable indy

Still sounds like air in the system and/or they don't know what they are doing. I've think I have only seen one other board member talking about the booster failing and that was due to water getting in the system. Even a small amount of air in one place can make it feel soft, but I'd also check the level in the master resevoir to see if it is down at all. Also have a look at the brake lines. If the tech just let the caliper hang by the line you could have a leak (but you'd hope they would notice that when they re-bled).

For what its worth, the dealer I used to have work on my car in NVA failed to put shims or anti-squeal on the pads, didn't set the e-brake and never bled the brakes so I had to go back 2 more times. Either they don't care or rush through the job. Thanks to this board I've re-done the brakes myself - not at all difficult and I know it is done properly. If you aren't comfortable going the DIY route, find a qualified indy mechanic and buy parts on-line. A whole lot more reasonable cost wise.
 

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Discussion Starter · #6 ·
Still sounds like air in the system and/or they don't know what they are doing. I've think I have only seen one other board member talking about the booster failing and that was due to water getting in the system. Even a small amount of air in one place can make it feel soft, but I'd also check the level in the master resevoir to see if it is down at all. Also have a look at the brake lines. If the tech just let the caliper hang by the line you could have a leak (but you'd hope they would notice that when they re-bled).

For what its worth, the dealer I used to have work on my car in NVA failed to put shims or anti-squeal on the pads, didn't set the e-brake and never bled the brakes so I had to go back 2 more times. Either they don't care or rush through the job. Thanks to this board I've re-done the brakes myself - not at all difficult and I know it is done properly. If you aren't comfortable going the DIY route, find a qualified indy mechanic and buy parts on-line. A whole lot more reasonable cost wise.
That's the thing that bothers me . . . I read the thread about the booster replacement after the rain/car wash. My car is only ever hand washed and has never been anything more than a light sprinkle. She's a real garage queen. But, the day they worked on my car, they washed it. I'm not sure how and I'd have a very hard time believing that the drain hole under there could be clogged because my engine compartment is clean enough to eat out of. The car has not ever been parked outside and I just don't let it get dirty. Strange coincidence? But, as you say, given the apparent lack of failed booster reports, it concerns me. Thanks for the feedback.

Greg
 

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That's the thing that bothers me . . . I read the thread about the booster replacement after the rain/car wash. My car is only ever hand washed and has never been anything more than a light sprinkle. She's a real garage queen. But, the day they worked on my car, they washed it. I'm not sure how and I'd have a very hard time believing that the drain hole under there could be clogged because my engine compartment is clean enough to eat out of. The car has not ever been parked outside and I just don't let it get dirty. Strange coincidence? But, as you say, given the apparent lack of failed booster reports, it concerns me. Thanks for the feedback.

Greg
A failed booster would make the brakes harder to press, not easier. It uses engine vacuum pressure to assist the movement of the plunger into the master cylinder, which is what actually provides pressure on the hydraulic lines that make the brakes work. So, if the booster was failing or there was a vacuum leak there you'd have to press harder to achieve the same hydraulic compression.

An easy to press brake pedal would indicate air in the lines, or a brake line leak that isn't allowing normal pressure to build in the hydraulic fluid in the lines. It's interesting you mention the pedal was fine at first but the next morning it was no good... sounds like a leaking brake line or something along those lines to me. At any rate, this doesn't sound like something where your booster would need replacement so you can probably save some money on that. Perhaps the master cylinder is bad... but it's odd it would fail immediately after a visit to the dealer. I suggest you take your car somewhere else!
 

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its very simple, if the brakes were ok before you took the car for service and now they're not then its something they did. either got air in the system, or somehow damaged the master cylinder.
 

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Discussion Starter · #9 ·
I got the service manager involved and they're continuing to work on the car. He said that, if it turned out to be something requiring repair or replacement, he would look to get BMW NA involved to help, given the very low miles and excellent condition of the car. We'll see . . . Thanks for the help so far and I'll keep you all updated.

Greg
 
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I got the service manager involved and they're continuing to work on the car. He said that, if it turned out to be something requiring repair or replacement, he would look to get BMW NA involved to help, given the very low miles and excellent condition of the car. We'll see . . . Thanks for the help so far and I'll keep you all updated.

Greg
Well, BMWNA didn't break your car. The dealership should get the dealership to pay for repairs. As NK said, if someone flushes your brakes, then your brakes don't work, I'd say they messed something up. The master cylinder doesn't just suddenly fail (because if it did people would be unable to brake all over the place).
 

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1. You were asked if they used the GT1 to bleed the brakes.


DID THEY????

This is the only way to get all the air out. I once had a system drain on me (dont ask) and it would not 'bleed' until they used the GT1..even then it was a PITA.

2. I suspect the dealer did something wrong to trigger this "failure". (Personally my suspicion is that this is all dealer error and there is no broken part.) As was also pointed out, this is the dealers problme, not BMWs problem.... Don't let them off the hook because they are "fighting with bmw for you"

A
 

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Check these items

A couple of basic tests you can do yourself in less than one minute:

-1. With the engine off, repeatedly pump the brakes till you get a hard pedal. Now hold heavy pedal
pressure and see if you have any noticeable movement of pedal toward the floor. If the pedal remains
solid and stays at the same height, the master cylinder is OK and not bypassing fluid internally past
the piston seals.

-2. While holding a hard pedal as per above, start the engine. The pedal should drop dramatically toward
the floor. If so, the brake booster is performing normally.

Regards,
Alan
 

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Discussion Starter · #13 ·
1. You were asked if they used the GT1 to bleed the brakes.


DID THEY????

This is the only way to get all the air out. I once had a system drain on me (dont ask) and it would not 'bleed' until they used the GT1..even then it was a PITA.

2. I suspect the dealer did something wrong to trigger this "failure". (Personally my suspicion is that this is all dealer error and there is no broken part.) As was also pointed out, this is the dealers problme, not BMWs problem.... Don't let them off the hook because they are "fighting with bmw for you"

A
I asked. The SA implied that this was unnecessary, even saying that he doesn't bother on his M3 . . . I am pushing and since they're still working on it, I suspect that they'll get it figured out eventually . . .


Thx,
Greg
 

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Discussion Starter · #14 ·
A couple of basic tests you can do yourself in less than one minute:

-1. With the engine off, repeatedly pump the brakes till you get a hard pedal. Now hold heavy pedal
pressure and see if you have any noticeable movement of pedal toward the floor. If the pedal remains
solid and stays at the same height, the master cylinder is OK and not bypassing fluid internally past
the piston seals.

-2. While holding a hard pedal as per above, start the engine. The pedal should drop dramatically toward
the floor. If so, the brake booster is performing normally.

Regards,
Alan
Thanks! If I had the car, I could test . . . :)

Greg
 

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I asked. The SA implied that this was unnecessary, even saying that he doesn't bother on his M3 . . . I am pushing and since they're still working on it, I suspect that they'll get it figured out eventually . . .


Thx,
Greg
I need a double face palm here!:1zhelp:

If they didn't bleed with the GT1, 95% chance that is the issue. Tell him to "humor you" and rebleed everything using the GT1 as per BMW specs. It will take half a bottle of brake fluid and 30 minutes.

Regards,
Jerry
 

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An unacceptable response by the SA

I asked. The SA implied that this was unnecessary, even saying that he doesn't bother on his M3 . . . I am
pushing and since they're still working on it, I suspect that they'll get it figured out eventually . . .


Thx,
Greg
Your SA is sadly misinformed, at best. If I were to venture a guess as to what caused your problem, it sounds like
they let the pressure pot (pressurized container of fresh fluid) run dry. That resulted in air being introduced in
the supply lines upstream of the DSC/ABS module. After refilling the tank, the flush/bleed proceeded along, all the
while the doofus tech was saying to himself; "Hey, no problem". However, once air was allowed into into that
closed-loop, there is absolutely no way to remove it, except by use of the GT1. But, using the GT1 and performing
a full bleed procedure is very time consuming and will use a lot of fluid, hence the "Hey, no problem" rationalization.
Just a potential theory, it may be completely off-base.

In my opinion, performing a proper flush of the entire system (to include the hydraulic module) should be done at
least once every 2-3 years. DSC interventions will likely become much smoother and the response times reduced,
ABS engagement cycles shorter and the function of the high pressure pump can be tested. A properly maintained
system could well save your hindquarters during some unforeseen event. Stuff happens!

Regards,
Alan
 
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