Hints or tips on bleeding brakes

[Shhmaudi]

Back story, I took my calipers off for paint/ new pads/ rotors. Fwiw I am running B6 rear rotors and pads

Anyways I have bled the shit out of the brakes with a power bleeder and the old fashion way. No bubbles, I even went as far as taking the calipers off and rotating/tapping the calipers rwit a dead blow with the power bleeder on to dislodge any trapped air.

Now I can get a nice solid pedal with the car off but when I turn the car on the pedal turns to mush..

Master cylinder worked fine before the brake refresh.. I'm at a loss here any ideas? Brakes do work, however, the pedal is a little mushy still..

Possible that the abs module/MC got some air in it while the lines were off? Is there anyway I can bleed those with vag-com?

TIA

[MacDaddy]

This happens all the time and i have been looking but cant find a solution.

However i was working on a friends 2007 silverado and had a similar issue (also a bosch 5.xx ABS system) we were doing the 2 man bleeding when air somehow got in, idk how. The solution was to powerbleed only, dont touch the pedal and then it went back to normal.

I think that may be the solution.

[Audibot]

You can bleed the ABS pump via VCDS. Just need to go into the module, select Output Tests, and follow the prompts.

Funny enough a few months ago I replaced my rear brakes, and somehow the fronts ended up with air in them. Took a lot of 2-man bleeding to get an extremely solid pedal!

[themadscientist]

I've never had to run the pump when using a power bleeder. what psi are you using the bleeder at? If the lines were disconnected for a while, you would need to start bleeding at the master and work your way down.

[seanf86]

I had a shitty soft pedal when I first installed C5 A6 ATE calipers on my wifes B6, after bleeding and bleeding I took it for a drive and jammed on the brakes and got the abs to activate and the pedal firmed up after that.

I can't remember the exact reasoning but my college auto instructor told us about the seal not sliding down the caliper piston after a brake job so the seal would stretch and pull the piston back meaning more pedal travel until contact, a good sold romp on the pedal would force it to move and it would stop pulling the piston back so far and the mushy pedal would go away.

[Shhmaudi]

You can bleed the ABS pump via VCDS. Just need to go into the module, select Output Tests, and follow the prompts.

Funny enough a few months ago I replaced my rear brakes, and somehow the fronts ended up with air in them. Took a lot of 2-man bleeding to get an extremely solid pedal!

I tried that and my vag com keeps timing out. really strange..

I've never had to run the pump when using a power bleeder. what psi are you using the bleeder at? If the lines were disconnected for a while, you would need to start bleeding at the master and work your way down.

I didnt realize you can bleed the master? how do you go about that? I am running the brake bleeder at 10-13 psi

I had a shitty soft pedal when I first installed C5 A6 ATE calipers on my wifes B6, after bleeding and bleeding I took it for a drive and jammed on the brakes and got the abs to activate and the pedal firmed up after that.

I can't remember the exact reasoning but my college auto instructor told us about the seal not sliding down the caliper piston after a brake job so the seal would stretch and pull the piston back meaning more pedal travel until contact, a good sold romp on the pedal would force it to move and it would stop pulling the piston back so far and the mushy pedal would go away.

I was thinking about going to a sandy parking lot near buy and jamming the brakes. I have been driving the car and the pedal cleaned up a little bit but still not where I want it/ where it was before..

My other idea was possibly bleeding it with the car on.. Since I can get a nice hard pedal with the car off

[Zba]

Run the bleeder at 2 bar. Watch your res to make sure it's it not going to pop (or replace it). On air powered bleeders; If you use the vacuum sucker at the bleeder and less than 2 bar pressure at the res the pulsating vacuum at the bleeder actually introduces air into the system at the caliper.

The more pressure the better, until you pop the reservoir. Then you went too far.

[themadscientist]

I tried that and my vag com keeps timing out. really strange..



I didnt realize you can bleed the master? how do you go about that? I am running the brake bleeder at 10-13 psi

Where the lines connect to the master, and the pump. If the master runs out of fluid I never skip this step. Messy PITA, but usually necessary.

The other wayyyy out there possibility is a failed booster. I just recently experienced this for the first time on a '13 tdi passat that had water damage. The booster was overdoing it and keeping the pedal held down.

[Shhmaudi]

Run the bleeder at 2 bar. Watch your res to make sure it's it not going to pop (or replace it). On air powered bleeders; If you use the vacuum sucker at the bleeder and less than 2 bar pressure at the res the pulsating vacuum at the bleeder actually introduces air into the system at the caliper.

The more pressure the better, until you pop the reservoir. Then you went too far.

Lol Ive popped a reservoir before, it was tired tho.

Where the lines connect to the master, and the pump. If the master runs out of fluid I never skip this step. Messy PITA, but usually necessary.

The other wayyyy out there possibility is a failed booster. I just recently experienced this for the first time on a '13 tdi passat that had water damage. The booster was overdoing it and keeping the pedal held down.

I never ran the master dry. but I did have the lines disconnected for a couple weeks so air probably made its way.. Maybe ill try bleeding the MC tomorrrow. I did the test with the booster.

Hold foot on brake, start car, if the pedal goes down booster is good. If it stays hard its fucked.. plus it was working fine before too

[themadscientist]

Lol Ive popped a reservoir before, it was tired tho.


I never ran the master dry. but I did have the lines disconnected for a couple weeks so air probably made its way.. Maybe ill try bleeding the MC tomorrrow. I did the test with the booster.

Hold foot on brake, start car, if the pedal goes down booster is good. If it stays hard its fucked.. plus it was working fine before too

They can fail in more than one way, believe me.

[S4gasm2.7t]

May be a stupid question, but did you make sure you put them on the proper side of the car. As I tech, I've seen even some "professionals" do this. Visually check the calipers and ensure the bleeders are in they're physically highest position (as air rises in fluid) if you put them on the wrong side, you can bleed as much as you want but never get the air out. Again not at all saying you did this but it is a possibility of what issue may be happening. Good luck.

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[Shhmaudi]

May be a stupid question, but did you make sure you put them on the proper side of the car. As I tech, I've seen even some "professionals" do this. Visually check the calipers and ensure the bleeders are in they're physically highest position (as air rises in fluid) if you put them on the wrong side, you can bleed as much as you want but never get the air out. Again not at all saying you did this but it is a possibility of what issue may be happening. Good luck.

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Lol, not sure thats even possible with how the ebrake cable is routed/mounted. #nevergofullretard

[S4gasm2.7t]

May not be. Never tried to do it so I don't know. What I do know is that on most vehicles (key word there lol) the calipers are symmetrical (with the exception to ebrake cables) and the only difference is where the bleeder is placed on the caliper. But you may be absolutly right. I haven't swapped rear calipers on my car yet so I don't know off the top of my head.

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