Bleeding the brakes and how to ensure no air

[peake]

I recently bled the brakes on my 850i. The fluid released from the brake system was more black than light yellow. The reason for the job was that the brake pedal was feeling a bit soft and not too distinct when braking. All went well until the last wheel when some air came into the system. Since then the brake pedal needs to be operated in small rapid movements to brake, which it does efficiently. Now to the question, how do I ensure that the ABS is free from any air. I do not have any TIS or DIS equipment and there is no BMW rep around having knowledge or equipment either. Are there any useful diy procedures available.

//Peter

[Gary Knox]

If it were me, I'd do another brake bleeding procedure, but I ONLY bleed brakes using a pressure bleeder. With these, I am diligent about being sure the master cylinder reservoir is always near the full mark, I keep the pressure on the fluid in that reservoir at about 10 psi when bleeding. RR, LR, RF and LF in that order for left side driving cars where the master cylinder and reservoir are on the left side of the engine compartment. i assume it would be the mirror opposite for right side driver cars - depending on whether the master cylinder & reservoir is on the right side of the engine compartment (If it is on the left side, then the same order as I've posted (with Wuffer's correction!!!) here.

Hope you can get the air out.

Gary

[NevadaMike]

+1 on the pressure bleeder. They are cheap (under $50) and do the job. Follow the sequence Mr. Knox suggested above.

[Wuffer]

LR, RR, LF and RF in that order for left side driving cars.

Hmmm...I was always taught that the furthest away from the master cylinder first. IMHO, that makes it RR, LR, RF, LF on lhd cars doesnt it?

[JDP530]

I made up my own pressure bleeder system by using an old master cylinder cap and threading/gluing a male air hose connector into cap and use this cap on car. I also used a paint gun moisture trap to catch any moisture in air line. Turn down regulator to zero, connect air hose, and then turn regulator to about 5 lbs/in air pressure. I usually start at farthest caliper and use a piece of clear vinyl tubing on bleeder with hose running through hole in cap into a bottle to catch dirty fluid. You just have to refill master several times to complete the job.

[wolfebrian2120]

This is the one I bought. it works great. I have used it several times and clean it afterward. Since I rebuilt my front calipers and bled the old dirty fluid out I have a nice hard pedal now.

https://www.ecstuning.com/b-schwaben.../018222sch01a/

[Sniff38]

Hmmm...I was always taught that the furthest away from the master cylinder first. IMHO, that makes it RR, LR, RF, LF on lhd cars doesnt it?

I was just going to say the same thing Wuffer but you beat me to it. Always bleed the caliper furthest away from the master cylinder first.

Sean

[Gary Knox]

Wuffer and Sniff38,

You gentlemen are absolutely correct. Some kind of mirror image brain cramp when I first posted. Have now corrected it.

Gary

[ECSTuning]

This is the one I bought. it works great. I have used it several times and clean it afterward. Since I rebuilt my front calipers and bled the old dirty fluid out I have a nice hard pedal now.

https://www.ecstuning.com/b-schwaben-parts/compact-european-pressure-brake-bleeder/018222sch01a/

The compact bleeder is super super handy, I'm starting to like it more than my big bleeder. I think it's almost easier to place in the engine bay safely than the full sized bleeders.

-James

[Hyper]

...Now to the question, how do I ensure that the ABS is free from any air...

I've recently become the world's leading expert in this matter, having bled my system oh 30 or 50 times during the development of BBKoB.

Yes, use a power bleeder, but that is not sufficient.
A significant quantity of air seems to trap somewhere in the upper part of the system and seems to lead to compromised performance.

Based on the volume and lacking any other info about this I assume...
- air gets trapped in the ABS mechanism (rather than say the reservoir)
- and that's bad, not good, not meh.

My air extraction method is..
- Completely fill the MC reservoir and part way up the bleeder tube so that you can confirm that you will not be injecting air into even the reservoir.
- Pressurize the reservoir to 10psi.
- Rapidly open the bleeder at the tank, instantly slamming the pressure back to zero.
- Initially, observe a blast of bubbles flowing back up the tube from the reservoir.
- Repeat until the quantity dwindles, like in this pic...




Tip: when finally removing the tube, pinch it near the reservoir cap, to limit the mess.
Bring the reservoir back down to spec using a syringe or pipette.

[peake]

Thank you all for all the suggestions and solutions to the problem. I have no power bleeder so I had to solve the problem an other way and I did the following. I bought some 12' of vinyl tubing at the local hardware store. Fixing the tube to the bleeding nipple and then taking the other end of the tube into the fluid reservoir. By doing this arrangement my thought was to just circulate the brake fluid and releasing any trapped air back to the atmosphere in a closed loop arrangement. After opening the bleeding nipple I started to pump the brake pedal. The fluid started to flow and I could see some air coming trapped in the fluid. Doing this with all four brakes a substantial amount of air was released from the brake system and the ABS. At the right front wheel I noticed that the fluid passed was looking foamed, the air bubbles were very small but many and it took some 5-10 minutes for the small bubbles to form larger bubbles that could be released out into the atmosphere at the fluid reservoir. After doing this the breaks felt like new I am happy. A side effect of this is that the ABS is suddenly working much better than before I started to change the fluid in the brake system. Before changing the ABS did not work at all. I guess it was because I could not build up enough pressure in the system. I bought my 850 the summer 2014 and as far as I can understand the brake fluid has not been changed for many years, the fluid that was changed was looking quite bad, all black and dirty. Next time I will have a power bleeder when changing the brake fluid.

//Peter

[Gary Knox]

Creative approach without having a power bleeder. I'm sure you will like the bleeder when you use it next time you perform the brake fluid replacement.

Congratulations on having good brakes again.


Gary

[bdiefAZ]

Has anybody successfully jumped the ABS relay to activate the pump and remove air from the ABS circuit? If so, could you share your experiences?

[Timm]

Easy!:

https://youtu.be/0DedTBL9dKk

From:

http://www.meeknet.co.uk/e31/Timm_BM...p_Problems.htm

[bdiefAZ]

Thank you Timm!

[cartoonz]

Having recently introduced to these - http://www.russellperformance.com/mc/speed-bleeders/
I can say that I'll be installing those on every car I have.

[ChrisFuture8]

Would you happen to have the part number of the speed-bleeder valve for our e31, Cartoonz?

-Chris

Having recently introduced to these - http://www.russellperformance.com/mc/speed-bleeders/
I can say that I'll be installing those on every car I have.

[cartoonz]

Would you happen to have the part number of the speed-bleeder valve for our e31, Cartoonz?

-Chris

I don't. Have not put them in any of my E31's yet. There are only a couple of different flavors to them though, I will be figuring out sizing myself soon. I recently swapped them out in a vintage Datsun truck, and they are sweet. The silly looking "bleed bag" they have as an accessory is actually awesome too...

[peake]

Having read these last answers I realize that I am likely to still have some air in may system. From Timms excellent, as usual, explanation about the motor and its activation on the ABS control unit I understand that some air might still exist in my system. It possibly explains where the foaming of the brake fluid could have taken place. As I observed that there was some very small air bubbles in my brake fluid possibly formed by foaming. These small (<0.1 mm dia) bubbles did not move as easily as larger bubbles did in the fluid and therefore did not form larger bubbles in the fluid. For me it meant that the only way to successfully get them out from the fluid was to slow down the whole operation so as to wait for the small bubbles to gather inside a vertical loop of my vinyl tubing. The speed that the small bubbles moved was in the range of 10 mm/minute in a vertical tube. Maybe this is of no importance. I have to investigate further or are there anybody that has the knowledge.

[clockwork]

Easy!:

https://youtu.be/0DedTBL9dKk

From:

http://www.meeknet.co.uk/e31/Timm_BM...p_Problems.htm

Hi Tim, et al, can anyone point me to where this ABS relay is in the 1991 850i's, please?
I've not been able to find it in the engine bay.

[Sleepyhead97]

I use a hose and a 2 liter soda bottle. Put some fluid on the bottle to cover end of hose.. Other end of hose secured to bleed valve. Crack bleed fitting pump brake only halfway. Going full to floor pushes orings which usually stop halfway in master cylinder to push over a point in the cylinder bore that could have a ridge...causing a cut on oring

- - - Updated - - -

Has anybody successfully jumped the ABS relay to activate the pump and remove air from the ABS circuit? If so, could you share your experiences?

Couldnt you take it on a gravel road and slam brakes to activate yourself? Ive done this on old chevys and it works. On the chevys they also have a small port on abs for bleeding

[Timm]

The ABS pump relay is fitted to the pump on the early cars...

[clockwork]

The ABS pump relay is fitted to the pump on the early cars...

well of course it was

[cartoonz]

you can also use DIS... there is a full section & procedure for bleeding the ABS

[clockwork]

you can also use DIS... there is a full section & procedure for bleeding the ABS

Apparently I can't operate the ABS pump with DIS on my Japan e31

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