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Brake bleeding - how to?

Discussion in 'A4/S4 forum(B5 Chassis)' started by TeKnodriver, Feb 28, 2012.

  1. TeKnodriver
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    TeKnodriver Biodiesel Purrrr

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    [Feb 28, 2012]
    been planning to bleed the whole system for a while now but there are a couple of things not mentioned in the Haynes guide:

    -does the A4 have a rear brake balance valve [like on Golfs] that needs clamping open?

    -does the ABS pump need to be set to cycle like on some of the newer Audis?

    also, just to confirm I guess, what wheel would be best to start on -
    Driver side rear?

    Thanks!!
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  3. kev1000
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    kev1000 Member

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    [Feb 28, 2012]
    Not sure about valve or ABS but I think you start at the furthest away and finish at the nearest to the reservoir.
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 28, 2012]
    I've never had to bleed the ABS, even from a completely drained system.
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  5. TeKnodriver
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    TeKnodriver Biodiesel Purrrr

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    [Feb 28, 2012]
    I just need to renew fluid - don't think there's any air in the system
    will the pump just flush through?
    my initial thought was the valves inside would be open until the ABS cut in when wheels lock
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 28, 2012]
    Yeh in that case just ignore the ABS system entirely.

    What i'd do, is carefully remove the reservoir, and allow it to drain into a plastic tub.

    Then refit, fill with fresh fluid and attach eezibleed and pressurise to NO MORE than 10psi.

    This way your not diluting your good fresh fluid down with manky old ****, and keeping it below 10psi should ensure you dont blow up the reservoir.
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  7. TeKnodriver
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    TeKnodriver Biodiesel Purrrr

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    [Feb 28, 2012]
    Thanks for info, sounds like what I had in mind...

    was going to suck out the old fluid from resevior with big syringe - this is what i did on other cars -
    will that be OK?
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 28, 2012]
    I think there was some reason that wouldnt work, so i just pulled it off.

    It just sits pushed into two rubber things.
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  9. TeKnodriver
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    TeKnodriver Biodiesel Purrrr

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    [Feb 28, 2012]
    hang on -
    does the fluid not pour out when the resevoir is removed from the cylinder?
    #8
  10. gary3306
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    gary3306 Active Member VCDS Map User

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    [Feb 28, 2012]
    Having been in the trade for over 30 years, I have bled the odd braking system or two. All you need to do is attach a pressure bleeder, them eazibleed things are good enough for what you need. Then start at the furthest wheel away from the master cylinder and crack off the nipple. bleed that caliper for about 15 seconds. Work from the furthest calliper to the nearest calliper to the MC. Once done, start again at the first calliper and bleed all 4 for a second time, then a third time. All the time checking that your eazibleed bottle remains topped up. By the third time of bleeding, you should be seeing lovely new clean and air free fluid coming out. Good luck.
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  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 28, 2012]
    Yep, be quick, have a tub ready and keep the cap on so theres vacuum inside and you wont spill much! If you do spill any, wash it off immediately with lots of water!
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  12. dubstar81
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    dubstar81 Member

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    [Feb 29, 2012]
    I bled the brakes on my n reg tdi last week. I had to replace the abs pump and my reservoir was cracked so replaced that along with the rubber seals. Handbrake off and started with o/s rear calipar, then n/s front, n/s rear finishing off with the o/s front.
    I bought an easy bleed kit off ebay for about 15 quid and it was spot on but make sure you deflate the spare tyre a little before bleeding else you will crack your reservoir like the previous owner did on mine. Hope this helps
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  13. TeKnodriver
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    TeKnodriver Biodiesel Purrrr

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    [Feb 29, 2012]
    thank you all for the info...
    had a try today and the resevior was looking like crackle-glaze at the back - never seen that even on older VAG cars
    got scared and ran such a low pressure through the EZbleed it hardly pushed the fluid though
    that and one of the rear bleed nipples was rounded-off... grrr

    will be buying new resevior and doing it properly soon!

    @dubstar - how did you know it needed newe ABS pump?
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  14. dubstar81
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    dubstar81 Member

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    [Feb 29, 2012]
    Basically when i brake and i get to about 10 mph and the brake pedal starts fluttering and the pump would would flash up. I replaced it and it didnt sort it so i put the old one back in.
    I then found out the guy who had the car before me changed all the discs, pads and bottom arms. I think he must of disturbed the abs sensors so i adjusted them. The old reservoir was all crackled up at the back too. The think the guy spent so much money getting the car sorted and then cracked the reservoir on pressure bleeding he just had enough and stuck it on ebay.
    I snapped the car up for a mere £461, replaced reservoir for £45 inc vat from audi, pressure bled it and it works spot on now. I would definetly order new and order a pair of rubber seals too. It is really easy to take off. It simply pops off. I wore goggles just in case. It can get messy. If one of yours rear bleed nipples is seized just make sure you give the opposite side a good bleeding. That is what happened on my old B5.
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  15. spartacus68
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    spartacus68 Member

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    [Feb 29, 2012]
    Before you start bleeding the system it's worth getting all 4 wheels off the ground. It's a pain otherwise. Last time I did I took around 1.5 litres of brake fluid out of the system until I was satisfied the new fluid was clear and golden. Worth investing in some new brake nipples too. The original ones (thread was corroded) so sometimes they don't tighten sufficiently. I've done it with someone pressing the brake, then moving to the next point. Each time checking the fluid reservoir is topped up.
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  16. dubstar81
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    dubstar81 Member

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    [Feb 29, 2012]
    I have heard some horror stories about manual bleeding on some of the newer cars. It apparently strips the rubber seals within the master cylinder. I bought 5 litre tub of brake fluid in the end from gsf for £24. I reckon i used nearly half bleeding mine.
    #15

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