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Discussion Starter #1
So, one caliper at a time, I bleed the brake lines. After each caliper, I top up the reservoir so the fluid doesn’t drop too low. Then by the 3rd caliper, the brake pedal suddenly doesn’t have any pressure... and if something comes out the rear caliper, it’s foam

Any ideas? Do I have to give it a moment?
 

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Did the reservoir get completely emptied out during whatever brake service you performed?

If so, it is possible the ABS pump/block drained as well. I had some odd things happen when I replaced my rear calipers, took quite a lot of fluid and several attempts to get the bleeding completed.

If you have VAG COM there is an ABS priming mode I believe.

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What order are you bleeding the calipers in? Rear passenger, rear driver, front passenger and then front driver. You don't have to cycle the ABS to get a good bleed.

When you changed the brake line did the fluid drain completely? If so, you'll need to run probably close to a liter through the system.
 

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Discussion Starter #4
Wish I had a VAG... I’m all manual. No suction equipment or anything
 

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Discussion Starter #5
What order are you bleeding the calipers in? Rear passenger, rear driver, front passenger and then front driver. You don't have to cycle the ABS to get a good bleed.

When you changed the brake line did the fluid drain completely? If so, you'll need to run probably close to a liter through the system.
Thinking all I had to do was the passenger front caliper as that’s the only one I replace so far, I did that one first.

So with calipers done out of order, how do I do this manually? Start the correct order and go from there?
 

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You can get a good bleed accomplished manually with two people. I've never used my VCDS to bleed brakes.
 

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Make sure the system is closed (bleeder screws and hoses tight) then start with the rear passenger caliper.

The logic is to start the furthest away from the reservoir and purge the air out of each brake line section. You will have to do each caliper unfortunately.
 

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Discussion Starter #8
Just curious, as I tend to be, I checked the fuses. Fuse position 41 for ABS was burnt out. Perhaps the ABS pump?
 

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You can get a good bleed accomplished manually with two people. I've never used my VCDS to bleed brakes.
Agreed, just makes it easier. Have you done the one man method of a hose in a bottle? That's how I did my Allroad. Took a long time but it worked.

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I've never tried to bleed brakes single handedly. Especially considering my luck. Either the bottle would tip over or the end of the hose would come up out of the fluid.
 

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Discussion Starter #11 (Edited)
I have a clear (empty) mayo jar with the bottle pouring stopper from a bottle of olive oil that just so happens to perfectly have a tight fit on a 5/16th (inner) fuel line hose. In the mayo jar I have a Small jalapeño jar filled with custom brake bleeding rocks that grow in my yard:

99382
 

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Discussion Starter #12 (Edited)
There’s no action yet... I pour in a bit to fill, pump the brakes; repeat... I’ve poured in about a half litre and it’s disappearing (to where???) but nothing is coming out the passenger rear caliper... I should just keep filling/pumping and it will eventually work?
 

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Just curious, as I tend to be, I checked the fuses. Fuse position 41 for ABS was burnt out. Perhaps the ABS pump?
Fuse 41, 25 amps, powers the ABS solenoid valves (via a relay).
For the ABS with ESP, there are two pumps:
  • V156 Hydraulic pump for traction control: Fuse 42, 25 amps (I'm 99% sure)
  • V39 ABS return flow pump (on the ABS control module): 60 amp fuse, probably on Aux Relay panel
Ref: Bentley schematic 55 (there are several schematics, depending on the exact ABS)
 

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Discussion Starter #14
This has become the latest workout craze. I’ve been pumping this brake pedal and topping up the fluid reservoir for about an hour now. Then I saw some fluid coming out of the passenger rear caliper, and I thought that was it, but again, I’m pumping the pedal and topping up again... wth? What should I expect here? Help please
 

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Are you certain the new caliper you put in is fully sealed? No leaks or air bubbles at the bleeder or the brake line? That much fluid has to be going somewhere. Did you pull the lower dash cover and check for fluid leaks? I don't think it would be sucked into the power brake vacuum reservoir without the car running, but I guess it's possible.
 

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when you changed out the caliper did you seal up line while you were working on it.? You need to pump brakes,then while pushing on pedal open bleed valve to let out air/fluid ,pedal will go to floor as you continue to push, tighten bleeder valve ,let pedal up. repeat this sequence a couple of times.I do not know how you would do this by yourself. The other thing of caution is that on an older car the master cylinder piston seals might get damaged from internal corrosion within the master cylinder itself when pedal/piston is pushed to the linear limit when bleeding.
 

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Discussion Starter #17
I’ve checked all under the car. Nothing is leaking. - @cchief22 see those are awesome instructions that simply were not in any of the 20 odd videos of changing a caliper I happened to find. The answer would be no to your queries. Well, I did seal up the line, but not while someone was pushing down. So I might also need a new master cylinder... If the master was still ok, what should I do to finish? If the master was not ok, wouldn’t I see fluid coming out from it somewhere if a seal was broken, or is that internal?
 

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your master cylinder may be, probably is just fine,just airing on the side of caution, do not even worry about that......however I am as curious as you are, where did all the fluid go or is going? I sometimes see someone replace a caliper,and leave the line "open" over a drain pain overnight while working on their car allowing air to get in and fluid to flow out. There should be some better tutorials on how to bleed brakes than how I explained like a step by step. I know for sure that you start at RR,then LR,then RF then LF........ Are all your rotors still on car or is driver rotor off as assume you are replacing both on the front ? You'll get it,as you have already done the other major hard stuff, starter ,alternator, etc.
 

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It’s possible you let one reservoir compartment get too low and allowed air into that line. You have to refill high enough to fill over the divider. If so, hen it might be best to disconnect the affected line and “bench bleed” until you definitely got the air out.

Otherwise, could the master cylinder be leaking into the brake booster? Sounds strange, but I don’t know where else fluid could be going.
 

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Well I might as well confess.....my mysterious fluid loss (note;years ago as a neophyte), replaced calipers and rotors, did pass. side first,took a ton of fluid ,as I move to drivers side realized caliper was bolted up but with no rotor.....inner pad pushed out and piston at a smidgen from disengagement and boot stretched to its limit. Live and learn.
 
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