ABS brake fluid bleed question

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
dos jettas
Recently replaced front calipers, hoses, pads and rotors. Did normal pressurized bleed at ~12 psi pushing air, seemed to go well, except - you guessed it: mushy pedal. No hard grab. Did a couple bed-in runs ~40 MPH, slam pedal down to 20 MPH. I think I still have air in the system.
I'm thinking I need to cycle the ABS pump, but I'm worried the pump will suck the reservoir dry before I can dump more fluid in.
How do you all ensure you have a good amount of gravity-fed fluid so you can do the whole cycling thing and not have to worry about sucking in air? No one seems to sell a big screw-on funnel for this.
Please advise.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
Brand new brakes need more than a couple of bed in runs to fully get the grab going. The pad material needs to be deposited onto the rotor. They need to get hot, but you don't ever want to come to a complete stop. Until them, the pedal will feel kind of squishy. If it goes all the way to the floor, then I'd be worried about trapped air.

Usually the procedure to bed in brakes is about 40 to 15 mph without slamming the brakes, but decelerating safely, yet fast. Then let off the brake and roll out of it. Repeat 5+ times. Then you want to up it to about 60 to 15 mph...this time you want to slow down as fast as possible without locking the brakes up...and roll out of it. Repeat 5+ times. This should heat the rotors up enough to deposit the pad material.

If you don't have enough road to do that, the other thing I've done is drive around with the pedal depressed lightly giving it gas. You don't want to burn your clutch out, but this will essentially heat up the rotors pretty quick and deposit the material. You kind of want the same attack though, you want to drive for a min or so with the brake depressed while driving, then slowly let the brake off, give them a cool down period, and repeat.

I've had great success with both ways.

As far as the brake bleed goes, did you let the reservoir run completely dry when you did your bleed? I use a pressure bleeder as well. I mark where the clutch slave line T's into the reservoir. I don't let the brake fluid get below that mark or else you're bleeding the slave again.
If it was run completely dry, then it's possible that you have air in the ABS unit, but it would have to be pretty low to get to that point (to the point you couldn't see any in the reservoir at all. If you top off the reservoir before running the ABS cycle through VCDS, it should have plenty to complete the procedure.
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS
Bedding in as Krash notes produces great results: all cars that I've done end up with excellent braking.

Go back and re-bleed the brakes. Hopefully you have a power-bleeder. Sometimes one fails to get all the air out. Gotta be patient. Best is to suck out everyting in the reservoir and then re-fill with new fluid; then bleed the snot out of the lines to purge out all the old stuff, keeping the reservoir topped off. Again, having a power-bleeder is the only way to go (otherwise you tend to get rushed due to having someone helping).
 

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
dos jettas
Got it fixed.
I ran the vcds ABS bleed a few times until I was getting no bubbles. Took a full liter bottle. Brakes are great now!
I had at one point emptied the reservoir, and had to start over. PITA, but worth it in the end.
Thank you guys!
 

tgray

Veteran Member
Joined
Sep 12, 2004
Location
Marengo, IL
TDI
'02 Beetle, '05 Golf, 2000 Jetta, 2001 Jetta, 2002 Jetta
And with that kind of flush you know you have good clean fluid now through the system.
 

pruzink

Veteran Member
Joined
Sep 25, 2004
Location
Granbury, Texas
TDI
GLS, 2004, silver
Recently replaced front calipers, hoses, pads and rotors. Did normal pressurized bleed at ~12 psi pushing air, seemed to go well, except - you guessed it: mushy pedal. No hard grab. Did a couple bed-in runs ~40 MPH, slam pedal down to 20 MPH. I think I still have air in the system.
I'm thinking I need to cycle the ABS pump, but I'm worried the pump will suck the reservoir dry before I can dump more fluid in.
How do you all ensure you have a good amount of gravity-fed fluid so you can do the whole cycling thing and not have to worry about sucking in air? No one seems to sell a big screw-on funnel for this.
Please advise.
If you have Vagcom, you can actuate the anti-lock brakes using it, that will burp the air out of that loop & you should be able to then get it out of the bleeder valves on the calipers. Years ago, I bought my daughter a 2001 MK4 Jetta from a VW Dealership in Greenwich, Ct.; when I took the car for a test drive & the brake pedal was going almost all the way to the floor. I bought the car but told them they needed to fix the brakes, they put new pads & rotors but the pedal still didn't work until about 1/2 way. A day later she had to take the car back to college. The next time that she came home I used vagcom to actuate the ABS & return the pedal to normal. The other surprise I had was that the floor of the interior was sopping wet (sunroof drain leaks); I guess that was why the previous owner got rid of it.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Sometimes I've had to redo brake bleed, sometimes even a 3rd time. No good reason why.
 

tgray

Veteran Member
Joined
Sep 12, 2004
Location
Marengo, IL
TDI
'02 Beetle, '05 Golf, 2000 Jetta, 2001 Jetta, 2002 Jetta
Sometimes I have had to let the cars sit overnight and try again the next day if I had too many tiny bubbles through the system.
 
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