Why can't I bleed my brakes properly? (resolved)

[Letsgo]

Reaching out here before I begin my third attempt at bleeding my brakes. I've done this in the past dozens of times and for whatever reason this X5 has me stumped (first time bleeding it).

I took the calipers off to repaint them and in doing so I introduced air in the system.


Attempt #1:

I used a Motiv power bleeder and noticed getting brake fluid to the rear calipers was very slow. I thought it was x5 specific, regardless I got 350ml out through both rear lines (super slow), did the front another 300ml or so from each and put the car on the ground. Pedal went straight to the floor.

I would pump it 5-10 times and it would build some pressure then right back down it went.

Attempt #2:

Combination of power bleeder/2 person method. Got the car in the air and noticed that the rear calipers had 1/4" of play on the sliders, meaning the piston had not been pressed out at all from the first attempt so pads were not making contact with rotor. That for sure had to be the issue.

Tried power bleeding and activating the ABS module with a laptop, nothing. I barely got any fluid to move through the line, no air either, nothing (bleeder was at 15psi). Then I tried the 2 person method with someone pumping the pedal and me releasing the bleeder under pressure. After a few attempts the piston expanded out and every time pedal pressure was applied the rear calipers would work and there was no more play. They were working as they were supposed to (or so I thought).

I did the same for the front, put the car down...and still no brakes. It's a little better this time it takes 3-5 pumps to get temporary pedal pressure before i lose it (instead of 5-10 times), but pedal doesn't hold pressure, goes to floor.

I am about to embark on Attempt #3, any tips or advice?

[hilld]

I haven't done it on an X5, but on plenty of VW's and Audi's with the Bosch ABS pump/module, pretty sure the X5 uses a Bosch ABS as well. There was a setting to bleed the brakes in Vag-Com, that activated the pump and you had to follow a certain procedure, the software gave you the instructions. Not sure if there is something similar in the BMW maintenance software. Might want to google that. But I could be completely wrong here, so forgive me if I am.

[TheeE86]

I used my power bleeder for full flushes many times on various BMW models Including X5 and haven’t had any issues and never needed to do anything with the abs module.
Do you think you could have sucked in air at the brake master cylinder? Have you started the car and attempted to drive it?
Only tip I would give is to not fill the power bleeder with brake fluid. I leave it empty and just fill the reservoir when it gets low. I believe a full flush is about 1L of fluid.

[Letsgo]

It's possible that I've sucked air into the master cylinder, but unlikely because I followed the same power bleeder procedure that I always do and which has worked.

Yes I've tried driving the car, but with no pressure in the pedal I can't go far.

Does anyone have a procedure on how to activate the ABS solenoid during a bleed? I did that a few times during my bleed, but I am not sure if there is a specific sequence or point to do it at.

[RL18]

Do you have a scan tool like foxwell schwaben? I can look to see if there's something there for bleeding brakes

From my experience, if you let the reservoir go below half full you need to pull the master cylinder and bench bleed it to remove the air fully

I had that exact same issue with my chevy trailblazer when I replaced with the ext version calipers and rotors and painted the calipers. I had to pull it, bench bleed the master cylinder then put it back in and re bleed the brakes, starting from the furthest to master cylinder to the closest. Also helped to have speed bleeders. After about 10mins of bleeding it was perfect.

Also found this: https://www.newtis.info/tisv2/a/en/e...linder/GNOfGlQ


https://www.newtis.info/tisv2/a/en/e...k-ventilation/

[Letsgo]

Good call on the master cylinder, I think this may be the issue.

I found this on youtube on how to bleed it out without bench bleeding it. I will try it today and report back.

[RL18]

No problem! I learned that the hard way lol. I never want to do that every again lol

I'll definitely be more careful when I upgrade my x5d to the 50i calipers and rotors. Might even get the speed bleeders too

[Letsgo]

I tried attempt #3, some air came out of all lines...the constant here is that the rear calipers are bleeding extremely slowly. The front bleed out normally with the two person method (3 pumps, hold), the rears barely get any fluid out.

[Letsgo]

Well I think I figured it out. After some google-foo and youtube'ing I found this video. I was watching it thinking about it this guy is a dumbass and the video is a waste of time.

Sure enough, I checked my X5 and installed the left caliper on the right side, etc so the bleeder is on the bottom of the caliper not allowing the air to rise up and out of the caliper. I am the actual dumbass.

Attempt #4 to ensue.

[Letsgo]

Resolved.

Mistake 1 one was the calipers were on the wrong sides. Once this was corrected I still couldn't bleed the rear brakes.

Solution:

Air was trapped in the ABS module and I had to use Rheingold to trigger the pump motor and get the air out. I read half a dozen threads on various forums and not one explains the correct procedure on how to actually use the software to get the air out. This is what I did for it to work:

Pump pedal a few times to build pressure, trigger ABS module, open bleeder. I did this about 2-3 times and every time more and more air came out and fluid started flowing faster. I ended up opening the bleeder while a buddy was pumping the pedal while triggering the ABS module another 3-4 times, roughly every 5th pedal pump. This was sufficient to get all air out and for fluid to start flowing normally. So a total of ~6 pump purges were required.

I then moved to the rear driver's side caliper and that didn't require anything, air came out with normal manual bleeding and it started flowing freely after.

[hilld]

Originally Posted by Letsgo

Resolved.

Mistake 1 one was the calipers were on the wrong sides. Once this was corrected I still couldn't bleed the rear brakes.

Solution:

Air was trapped in the ABS module and I had to use Rheingold to trigger the pump motor and get the air out. I read half a dozen threads on various forums and not one explains the correct procedure on how to actually use the software to get the air out. This is what I did for it to work:

Pump pedal a few times to build pressure, trigger ABS module, open bleeder. I did this about 2-3 times and every time more and more air came out and fluid started flowing faster. I ended up opening the bleeder while a buddy was pumping the pedal while triggering the ABS module another 3-4 times, roughly every 5th pedal pump. This was sufficient to get all air out and for fluid to start flowing normally. So a total of ~6 pump purges were required.

I then moved to the rear driver's side caliper and that didn't require anything, air came out with normal manual bleeding and it started flowing freely after.

Nice work. We have all made stupid mistakes, so don't feel bad on the caliper installation. I have stories from the days when I turned wrenches for a living.