Brakes have failed😟 FIXED!!

[Clavurion]

Originally Posted by X5only

Pressure at max force:
Engine off - 31 bar
Engine running- 29 bar

Then it sounds like failed master cylinder if you are certain there are no other leaks in the system.

[X5only]

Originally Posted by Clavurion

Then it sounds like failed master cylinder if you are certain there are no other leaks in the system.

Thank you. It looks like there're no external leaks. The brake fluid has been at max level consistently.

[80stech]

try applying pressure SLOWLY with the engine off and no vacuum, if pedal drops with lite pressure but gets hard when you push hard then master cylinder is leaking by internally.

It's funny that the ECS info contradicts itself!

That being said it's not all that uncommon to need both since the booster travels and diaphragm stretches more when the master cylinder fails so it can take the maybe 'soon to go' booster with it.

[X5only]

Originally Posted by 80stech

try applying pressure SLOWLY with the engine off and no vacuum, if pedal drops with lite pressure but gets hard when you push hard then master cylinder is leaking by internally.

It's funny that the ECS info contradicts itself!

That being said it's not all that uncommon to need both since the booster travels and diaphragm stretches more when the master cylinder fails so it can take the maybe 'soon to go' booster with it.

Makes sense, thank you. I'll have both replaced. Yeah, it behaves as you said when applying pressure gradually. Approx $600 for parts sounds ok. I hope my regular indy doesn't quote some crazy price, otherwise I'll just bite the bullet and DIY.

[Factory6speed]

For bleeding the pressure bleeder is really nice. I use the wheel pins to hang the bottle from, once the wheels are off can probably do all 4 corners in less than 10 min. I'd be dreading reaching up and working on the pedal area much more. My metal brake pipes have a fair bit of corrosion, I worry about them and need to replace them. If I had what you have I would be really checking them, under the plastic covers etc as I know they are suspect. If yours are for sure ok I agree it is probably master cylinder.

https://www.amazon.com/Motive-Produc.../dp/B0002KM5L0

[X5only]

Originally Posted by Factory6speed

For bleeding the pressure bleeder is really nice. I use the wheel pins to hang the bottle from, once the wheels are off can probably do all 4 corners in less than 10 min. I'd be dreading reaching up and working on the pedal area much more. My metal brake pipes have a fair bit of corrosion, I worry about them and need to replace them. If I had what you have I would be really checking them, under the plastic covers etc as I know they are suspect. If yours are for sure ok I agree it is probably master cylinder.

https://www.amazon.com/Motive-Produc.../dp/B0002KM5L0

Thank you. I have that pressure bleeder. I probably might as well change the fuel filter while checking on brake pipes under that cover. To say the truth, I have a brake bleeding PTSD from the last time I tried it and don't want to ever try it again, especially for this major repair where there will certainly be air introduced into the system, a different ball game compared to doing a brake system service. Just reading this thread sends shivers down my spine. https://xoutpost.com/bmw-sav-forums/...ing-floor.html

[workingonit]

Originally Posted by X5only

Thank you. I have that pressure bleeder...To say the truth, I have a brake bleeding PTSD from the last time I tried it and don't want to ever try it again, especially for this major repair where there will certainly be air introduced into the system, a different ball game compared to doing a brake system service. Just reading this thread sends shivers down my spine....

I have the Motive Power pressure bleeder, too, but with the General Motors Cobalt/HHR cap attachment, not the one for my X5, yet. I also had a bad experience pressure-bleeding my wife's Cobalt, and don't want to think about another major brake job, anytime soon.

I renewed front & rear brakes (drums, rotors, shoes, pads, hardware) and she drove it for a couple weeks before she complained about the pedal sinking. At that point, I asked a friend to come help me, as I can't crawl under the car anymore ( too low, unlike the X5 and my pickup trucks).

We used a vacuum bleeder on all four brakes, and determined that I should replace the master cylinder ( my wife has a history of stomping on the pedal and blows out master cylinders).

So, I replaced it, and bought the pressure bleeder, for the next round. He was under the car again, I was upside, and using the Motive Power unit and my Foxwell to bleed both the brakes and later the ABS, over an 8 hour day (several unsuccessful tries).

Never got a great pedal feel, but if you double-tapped it, it worked fine. But it wasn't good enough for the wife .

She let it sit for a year after all the work I'd done (3 years total), and we sold it to a friend's kid. He got drunk and wrecked it two weeks later.

My wife bought a low-mileage Lexus, as a replacement, so she's happy, but still have bad dreams about the 2 years of working on her Cobalt, and watching it rot for a year afterwards. I sure hope I have better luck on my next brake job. Her '98 GMC is next.









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[X5only]

Wow, I hear you. I prefer deterministic DIY projects. Brake bleeding feels like an art, a complicated one. I always take brake bleeding to a shop that do it every day and are likely to do it successfully in a few hours.

[EODguy]

BMW Part Number 11667635657 (11-66-7-635-657)
4.4 and 4.8 only
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[X5only]

Originally Posted by EODguy

BMW Part Number 11667635657 (11-66-7-635-657)
4.4 and 4.8 only
Sent from Embassy network using Tapatalk

I sure hope it is the vacuum pump that has failed because it’s very easy to replace or repair. I’ve done it a couple of times in the past. Is there a way ro tell if it’s the culprit?