jrbpit

I am working on a 2012 Audi Q5. I had to remove the rear calipers because someone engaged the parking brake while I was changing the pads and rotor, frustrating story there. When I was putting the calipers back on, did not know I needed a scanner to tell the computer to retract the Electronic Parking Brake (EPB). Bought the scanner to retract EPB. I asked my FIL if the EPB was engaged, and instead of looking he hit the switch. The electronic parking brake pushed the piston all the way out of the caliper. To assiste with getting the piston put back in, I pulled the caliper and put it my vice and put the piston back in the caliper. After I got everything back together, I bought a vacuum pump to assist with the bleed, and I think I have gotten just a out all the air out of the system. However, when the car is running and I push the brake pedal down and hold it, it will go to the floor. I does this slowly and with a pretty good amount of force from my right leg. The pedal feels nice and firm, but when held it will go to the floor. Does the ABS system need to be burped? Is there something else that I'm missing? Can a good independent do this, or does it have to go to the Audi dealer?

I have used the pump on all four wheels to no avail.

Bob Petruska

There's nothing special about bleeding the brakes on a Q5.

You need to bleed in this sequence.

Bleeding sequence

1 - Left front brake caliper

2 - Right front brake caliper

3 - Left rear brake caliper

4 - Right rear brake caliper

If you feel the vacuum pump isn't doing a good job, then do it the old fashion way, connect a length of rubber hose to the bleed screw, put the other end in a small glass bottle, have
someone pump the brakes and push towards the floor and hold there, open bleeder, purge some fluid, close bleeder, pump and push again, repeat until no air bubbles in fluid in the jar. Do all 4 wheels this way.

I'm sure you know how to do this!

I have a vacuum pump bleeder and sometimes it just didn't do the job correctly, the old fashion way solved the problem.

MP4.2+6.0

Ugh! Yep, sounds like the old air in the ABS pump issue. I had to deal with this nightmare once on a 2000 A6 with ABS when I accidentally let fluid run down too far while bleeding. As in, never let that happen unless you have no choice like when replacing ABS hydraulic unit or master cylinder....

Two suggestions--1. read up on whether you can cycle the ABS unit with VCDS. And yep, you would need that or its equivalent. That allows opening and closing of the control valves to help get the air out. I have avoided the issue for 15 years or so, but function might still be there. Audi deleted the ABS cycling bleeding step somewhere along the way of its car designs, so it could be the electronics that facilitated it were changed. 2. Regardless of whether #1 is an option, basically pump your brains out... Lots o' fluid too. Took me a couple of hours and a whole buch of bleeding cycles at each wheel to be comfortable I got it. One of the practical keys is lots of stabbing and almost kicking of brake pedal, including when bleeders are all closed. That basically means manual bleeding BTW, at least the way I finally recovered. What you are trying to do is set up some vibration and fluid movement forces throughout the hydraulic lines and passages to assist getting the air out. I don't remember doing it, but even some (gentle) tapping on ABS hydraulic block with a rubber mallet or wood block could help. Not any metal lines or other fragile areas, but the basic casting.

Bob Petruska

There is nothing odd about the ABS bleeding, same as old fashion wheel bleeding method, just a lot of pumping and fluid.

BarryT

I bought a Motive power bleeder years ago. It makes brake fluid changes much easier.

Redd

Long time ago my local Ford dealer (a very innovative one in many ways) used to use a metal "pump" can to bleed to brakes. AFAIK the Motive power bleeder is the only tool on the market today that does the same thing, and it only has to be used *once* to give you religion. Makes anything else, everything else, look Mickey Mouse. (And may be available as a free loaner tool from some of the auto chain stores.)

Bob Petruska

I don't own one, but looks good, except what do you do when your are done bleeding and the master cylinder has all the excess fluid in the hose sitting above it. It looks like when you loosen the master cylinder adapter cap all that excess fluid is just going to leak all over the engine compartment.

This also seems to require a awful lot of brake fluid to get it to work, you can't save excess brake fluid that has be exposed to air and moisture.

I like the idea, but I rarely ever bleed brakes anymore, really don't need to unless changing the fluid (I don't), or have a hydraulic repair.

BarryT

I use it to change the fluid at the recommended intervals. When you slowly loosen the top of the power bleeder the fluid stays in the tube or drains back to the container. It really isn't that bad. I suck the excess fluid out of the reservoir with one of those medicine syringe things that the pharmacy gives you for your kids to take meds. It normally takes a bottle and a half or so to change all of the fluid.

Bob Petruska

So then there must be a check valve in the adapter cap. I can see that working and yes that would be acceptable.

BarryT

No, it has a rubber seal inside of the cap. When you release the pressure slowly using the pump on the top it sucks the fluid out of the line. It's been a while since I've used it, but my Q5 is due for a fluid change. It passed 30k miles today.