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Thread: Correct brake bleeding procedure with ASC+T?

  1. #1
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    Correct brake bleeding procedure with ASC+T?

    I recently learned that cars with ASC+T system need to be bled differently?
    Is anyone aware of such procedure??

  2. #2
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    Only if the reservoir ran dry - if you are just bleeding brake callipers then just bleed as normal (pressure bleeding helps). The ASC+T hydraulic block needs to be bled if the reservoir ran dry and air has entered the ASC+T block. If that is the case, the valves have to be opened to allow the air to be pushed out.
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    Quote Originally Posted by Timm View Post
    Only if the reservoir ran dry - if you are just bleeding brake callipers then just bleed as normal (pressure bleeding helps). The ASC+T hydraulic block needs to be bled if the reservoir ran dry and air has entered the ASC+T block. If that is the case, the valves have to be opened to allow the air to be pushed out.
    You mean the main pentosin reservoir? I changed the main reservoir metal filter after evacuating the fluid as well as small filter in the lower brass casing. So I take it I need to get the asc+t block valves open to bleed, how would I do that?

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    Bleed procedure from 1994 E31 manual with ASC+T. Hope this helps.
    Attached Files Attached Files

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    You mean the main pentosin reservoir? I changed the main reservoir metal filter after evacuating the fluid as well as small filter in the lower brass casing. So I take it I need to get the asc+t block valves open to bleed, how would I do that?


    NO. Tim is referring to the brake fluid circuit, NOT Pentosin.

  6. #6
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    Quote Originally Posted by LouM View Post
    Bleed procedure from 1994 E31 manual with ASC+T. Hope this helps.
    If I am reading this correctly this requires a special bmw tool?

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    Quote Originally Posted by e31gixxxer View Post

    NO. Tim is referring to the brake fluid circuit, NOT Pentosin.
    So brake fluid circuit is the one that has brake switches connected to it?
    Would simply changing brake switches allow air to enter and requires a bleed?
    I have a panic stop problem where if you hit the brakes fast and hard nothing happens, then brakes finally kick in. This could be the brake bomb but this started to happen immediately after, filter, fluid change and brake booster rebuild.. Also every time I hit the brake pedal I have a red brake light flash. Air in the system or brake bomb indeed??

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    Brake bomb's a gonner!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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    Quote Originally Posted by Timm View Post
    Brake bomb's a gonner!
    Copy that...

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    Quote Originally Posted by Timm View Post
    Brake bomb's a gonner!

    I second this. When I restored the Alpina 5.0, I replaced all the filters. The brake bomb was fine before the restoration, but afterwards it required replacement. You will need to also bleed the nipple on top of the block - located on the back driver's side of the engine bay. It is above the brake master cylinder located on the plate with 2 bolt heads. The best way to bleed it is to put a clear hose on it, and put the other end of the hose into the Pentosin canister with the lid off. It will take a while to bleed off and on as there is quite a bit of air in the system that is introduced when you change that lower filter in the brass bowl located on the front of the motor just in front of the oil pan. By using a clear hose, you can monitor the air in the fluid. When you think you have blead it enough, do it some more. Again, you will be surprised on how much bubbles there will be, as you will also be flushing the pump.
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    Never noticed this nipple before, just tried to look for it on the car...could not find it. Does anyone have a picture of it?

    Quote Originally Posted by rogbmw View Post
    I second this. When I restored the Alpina 5.0, I replaced all the filters. The brake bomb was fine before the restoration, but afterwards it required replacement. You will need to also bleed the nipple on top of the block - located on the back driver's side of the engine bay. It is above the brake master cylinder located on the plate with 2 bolt heads. The best way to bleed it is to put a clear hose on it, and put the other end of the hose into the Pentosin canister with the lid off. It will take a while to bleed off and on as there is quite a bit of air in the system that is introduced when you change that lower filter in the brass bowl located on the front of the motor just in front of the oil pan. By using a clear hose, you can monitor the air in the fluid. When you think you have blead it enough, do it some more. Again, you will be surprised on how much bubbles there will be, as you will also be flushing the pump.

  12. #12
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    Quote Originally Posted by dragon850 View Post
    If I am reading this correctly this requires a special bmw tool?
    I don't think so. The ASC+T pump looks like it is a pump and a couple of solenoids that open and close as directed by the control unit based on rear wheel slip. It is in-line and down stream of the ABS system to the rear wheels only. If you disable the ASC+T (the light on the instrument panel is on when it's disabled), both solenoids should be open and you should be able to bleed fluid/air through the ASC+T pump.
    Maybe the " special tool" manually turns on the pump so you can get the air out of the pump reservoir in the ASC.
    After you have bled the system, go out and try to break the rear wheels loose. I don't think that you will have a problem with that . With the system active, the ASC light should pulse off and on telling you it's functioning and attempting to control the rear wheel slip. I would also check the brake fluid after that to see if you need to add.

    I am working on replacing my ASC pump and some burned wiring from the pump. So this advice is based on what I have determined so far in looking at the wiring and studying the way the system is supposed to work. YMMV.

    LouM...

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    Here you go. Look just infront of the + jump terminal with the red letters.
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    OH, that guy, now I get it! Thanks!

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    Isn't the hydraulic system self bleeding? Or can air get trapped in the system?
    Regards,

    Brian
    Cave Creek, AZ

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    Quote Originally Posted by bdiefAZ View Post
    Isn't the hydraulic system self bleeding? Or can air get trapped in the system?
    The power steering side, or Pentosin system is self bleeding, the brake system or brake fluid side is not self bleeding.
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  17. #17
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    Stefan and I bled hydraulic system at the port that Roger illustrated, lots of air came out and the brake pedal feel is improved with better response. To clarify, this is a bleed port is for the hydraulic system, not the braking system. Pentosin is bled here, and the system is under high pressure. Open the port slowly and please wear safety goggles when doing this.
    Regards,

    Brian
    Cave Creek, AZ

  18. #18
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    Quote Originally Posted by bdiefAZ View Post
    Stefan and I bled hydraulic system at the port that Roger illustrated, lots of air came out and the brake pedal feel is improved with better response. To clarify, this is a bleed port is for the hydraulic system, not the braking system. Pentosin is bled here, and the system is under high pressure. Open the port slowly and please wear safety goggles when doing this.
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  19. #19
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    IMG_7084-1.jpgIMG_7085-1.jpgIMG_7086-1.jpg

    The saga continues:

    Stefan created some bleeder fittings to be installed beneath the upper hydraulic system sensor, which is the highest point in the system. These fittings enabled us to remove all air from the system, some of which was introduced to the system when the sensor was removed. After bleeding the air from the system at both fittings, the braking system seems to have more boost and a more positive braking feel.

    I replaced all hydraulic system hoses, sealing rings, accumulator sphere, along with both the canister filter and lower filter in 2013 prior to the Garberville trip.

    We will road test and report back our experience with this modification.
    Regards,

    Brian
    Cave Creek, AZ

  20. #20
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    old one but ......where can you get this tool (and really needed.....):

    Brake repair manual:
    34-0/8: Correct bleeding of the ASC+T hydraulic unit is only possible using ABS/ASC tester 34 5 110.

    Bake bleed tester.jpg
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  21. #21
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    Do you have to bleed the pressure regulator if you only have ASC?

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    Did you ever find or need this?

    Quote Originally Posted by clubE31 View Post
    old one but ......where can you get this tool (and really needed.....):

    Brake repair manual:
    34-0/8: Correct bleeding of the ASC+T hydraulic unit is only possible using ABS/ASC tester 34 5 110.

    Bake bleed tester.jpg

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