Brake Bleeding Problem

[TiAgX5]

Originally Posted by squidzilla

Is that not the same two year old fluid that is presently in the entire system? I figured it was fine being in there for two years and would be fine being dripped out of the right rear caliper. It dripped about half of quart of clear fluid so I could be sure.

The res fluid will usually have more moisture then the ABS module/line fluid, due to the res cap allowing more moisture absorption from the atmosphere.

[LVP]

Garrett I think that's the ticket. I think the pressure bleeder I'm using is part the culprit (Motiv). When I get it back, I'll try using it to pressurize only, not pressurize AND fill. So what I'll do is fill reservoir full, then pressurize, then bleed a corner, release pressure, fill, add pressure, bleed - and repeat until that corner is good. I won't rely on the bleeder to maintain the level as I suspect it introduces bubbles when you fill it with fluid and/or pressurize it.

[StephenVA]

Originally Posted by LVP

Garrett I think that's the ticket. I think the pressure bleeder I'm using is part the culprit (Motiv). When I get it back, I'll try using it to pressurize only, not pressurize AND fill. So what I'll do is fill reservoir full, then pressurize, then bleed a corner, release pressure, fill, add pressure, bleed - and repeat until that corner is good. I won't rely on the bleeder to maintain the level as I suspect it introduces bubbles when you fill it with fluid and/or pressurize it.

My own experience says you are correct. Use just the tank for pressure only, filling up the reservoir each time and you will be fine. I have used this procedure on approx five BMW models now and all end up perfect.
The right rear (passenger rear) has the longest run from the reservoir so take your time, bleed it completely as the fluid has to run through the master, ABS system, down the entire tube lines to the caliper. The dirt, scale, and dis colored fluid will make you think you taped into a used oil drum some where, but don't worry it will clear out after awhile. Just keep the pressure to approx 20 psi, reservoir filled and you will be ok.
I use the foot pedal method at the end to confirm all is functional and to release any "locked" air bubbles in the system. It requires a helper who can follow simple instructions.

Plan on every two years and you should be ok unless you introduce water or race the X.
Good luck and keep the wheels right side up

[admranger]

Originally Posted by LVP

Garrett I think that's the ticket. I think the pressure bleeder I'm using is part the culprit (Motiv).

I'm sorry, but the Motiv isn't the problem.

I've bled gallons of brake fluid over my 2 decades of track experience (HPDEs and a decade of racing where I bled before the race weekends and during the race weekends...). I've used a Motiv brake bleed for most of that time on a variety of cars (BMW) and trucks (Ford, Chevy). I've never had a problem with brakes being soft that was caused by the Motiv.

If you are introducing air into the system with the Motiv, you are doing something terribly wrong or I've been the luckiest person on the planet. My sample size in performing this operation is statistically significant. No small sample sizes here...

BTW: when you change brake pads, don't push the piston into the cylinder on the brake caliper without first opening up the bleeder. You don't want to push the crap that settles out in your caliper back up into the brake system.

BTW2: Use a small metal object to 'tap' the caliper as your are bleeding the brakes (I use the handle of a small ratchet wrench). That'll help release any stubborn air bubbles that are sticking to the caliper due to surface tension.

BTW3: Glad the brake problems of the folks in the thread have been solved!

[LVP]

I do that. I clear out as much as I can and fill with new fluid. I agree - why push through stuff you know isn't fresh. Just makes it all go a lot longer

[LVP]

Jury still out for me on the Motiv. But your experience is similar to the tons of others who post videos and swear by it. Now, the one i have may be very old, but it hold pressure. When I pump it up, I can hear it bubbling through the fluid. Last time I did my brother-in-law's car and we shone a light in the reservoir after removing the bleeder, it was full of micro bubbles. And his brakes went to crap. But I'll keep trying to find a way through with the pressure bleeding technique. I'm going to the shop tomorrow to try a pressure and vacuum bleed at the same time. I'll post results. I too find it hard to believe that many use the bleeder without issues.

For BTW: This is what I do - open the bleed screw, not letting the crud back up.
For BTW2: I use a dead blow hammer. Easier on the ears, same result.
For BTW3: I wish I was in this camp now. I'm not, but I most definitely will be

Cheers.

[LVP]

The indy shop tried pressure, pedal and vacuum bleeding without success. I've suggested the following:
- bench bleed master
- use GT1 to block off the ABS channels and see if issue(s) lie in master/abs circuits or in one of the channels somewhere after the abs
- bleed with vehicle running
- crack fittings at master and abs while bleeding under pressure

Any other ideas? What kills me is it had a good pedal, I tossed on new pads rotors, backed out pistons with bleed screws open not forcing up fluid and then pressure bled fresh fluid through the system (no pedal presses, just pressure and let it run through until clean). Pedal is mushy but stops when off and mushy but goes slowly to floor with medium, consistent pressure when vehicle on. It does still stop, because I had it out to bed in pads/rotors. I'm baffled as is the shop - and these guys have done nothing but BMWs for the last 25yrs.

The shop is also going to swap in a master they have and see if that does anything. Could have just freed up some gunk when I pressure bled it and messed up the seals. I'll keep everyone posted. If I ever get it working, I'll report findings and never touch the bloody brakes again

[SlickGT1]

This is absolutely nuts. I can't believe the amount of issues a simple brake bleed seems to cause people.

I need to bleed my brakes desperately, but this seems to make me nervous. I need to get my laptop back to working order and fire up the GT1. I think the fail you guys experienced is by not doing this correctly from the start.

[LVP]

It isn't just reserved to us X53ers either. I've done some searching and it plagues more people than you can imagine. Now, I'm not an idiot, but I really can't see what I did wrong and a shop who has been doing this for 25yrs can't seem to fix it or explain it either. It's nuts, I agree. It should be as easy as this video below, but alas the Germans and their complex ABS/DSC/whatever-else systems tend to complicate things a bit. I laughed when I watched this video. Can you imagine doing the X5 master like this and it working?
Fixing A Sinking Brake Pedal


But check out some of these various threads for some head scratching. All over the map.

Porsche issues
Sinking brake pedal - Rennlist Discussion Forums

More pedal sinking - pads this time?
Changed the brake pads - now the pedal sinks in

More bmw mysteries
e39 sinking brake pedal

See post #18 and #20. Bloody hell
http://www.xoutpost.com/bmw-sav-foru...s-floor-2.html

See post #2 and the pdf it references - these brake systems are so simple - unreal
Brake Pressure Sensor (DSC/ABS/BRAKE Trifecta) - Bimmerfest - BMW Forums

[TiAgX5]

Originally Posted by LVP

........Fixing A Sinking Brake Pedal........

Should say HACK mechanic for 43 yrs!

If a mechanic pulled my master cyl without first covering the surrounding area with plastic/shop towels I would give him a boot to the shorts!

Brake fluid strips paint off metal.

Doing a DIY vid for noobs needs proper info, like information about torque wrench use (for noobs who think "if I can still turn it, it not tight enough").