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I did a complete brake job which included new stainless lines at each wheel. Afterwards, I did a full fluid flush and bleed with my Motive power bleeder. I got clear fluid with no bubbles at all four corners, so I thought I was good. However, the pedal was horribly spongy. I did the same process again (power bleed working from front left to right rear), and got the same results, In total, I bled over 2 liters of brake fluid through the system and ended up with no bubbles, yet the brakes are horrible. They barely hold the car still at idle.
One thing that may matter - While doing this brake job, I painted my calipers. Therefore, the brake system sat open for a few days. I had a water bottle at each wheel and they each filled ~25% while the car sat.
1) Am I doing something wrong here? Is there something very different with this car (2014 A6 3.0)? I've used this same bleeder on several cars including my Q7 without issues.
2) I tried Google for this, and I found some recommendations to bleed the ABS pump. Opinions are all over on this, and so are the fixes. It seems every car uses a different VCDS process. I think I found the right process for my car, but than I ran into an issue. I can't read the green instructions in VCDS. I can't scroll, copy/paste, or anything else. I found one comment (quoted below) that kind of looks like what I'm seeing, but not exactly.
1) Starting procedure makes appear message "Press brake pedal and hold". You press pedal like a normal stop and instantly it drops near to the floor because ABS valves are opened and fluid goes into expansion chambers. Please keep pressing pedal like a normal stop, don't let it. After few seconds we can hear ABS pump activated for a few seconds, fluid is pumped from ABS unit to the master cylinder, so pedal is pushed back with force, you can feel your foot pushed back. Please don't be scared, keep pressing pedal like a normal stop while it's moved back and it's very important you let pedal come back, don't try to keep it down to the floor, it must come back to the normal brake position.
2) Second step appears automatically. "Release brake pedal and open FL/FR bleed screws". Easy. Let the pedal, get off from the vehicle and open both front bleed screws. it's clear that there is no reason to open bleed screws if brake system is not under pressure. This operation must obviously be done while a pressure bleeder is connected.
3) Third step appears only after confirm previous step. "Wait 10 seconds", ABS pump is automatically activated for 10 seconds. Brake fluid is moved from ABS unit to the master cylinder. (Must say that some people on the web believe that this pump activation is to pump fluid out of calipers, this is not true, fluid is pushed out by pressure bleeder, while ABS pump moves fluid from ABS unit to master cylinder).
4) Fourth step appears automatically. "Press brake pedal 10 times then close bleed screws". Another clue that this operation must be done with a pressure bleeder. In other cases, air will be sucked back every time the pedal is released. 10 pedal pressions just help old fluid (which is already pressurized) to be pushed out of the calipers in less time. They are not counted from VCDS in anyway, they are not counted from ABS unit, 10 pressions are a theoretical number of pressions to help fluid to be pushed out. I believe that they are not really necessary, we can let the pressure bleeder does its work until new fluid comes out without touching brake pedal.
Now if we press "continue" button, VCDS goes back to the first step and repeats the 4 steps in loop. So there is no message which confirms that procedure is complete. We have to decide when to stop it. When we are sure that only new brake fluid is coming out with no air we can stop at the step 4, we close bleed screws and select "Done, go back" then "Close controller, go back" buttons on VCDS, ABS unit status will return normal and we can disconnect VCDS and pressure bleeder.
1. Go to a a free area.
2. Remove the brake fluid reservoir cap.
3. Install the pressure bleeder cap which has a small opening. This is to allow the trapped air to come out without spilling brake fluid all over.
4. Start the car, drive fast and brake hard to engage the ABS. Do this forward and backward several times as I showed in the first few seconds of the video below.
5. Brakes should now work as designed. Install original cap and enjoy the ride.
1. Go to a a free area.
2. Remove the brake fluid reservoir cap.
3. Install the pressure bleeder cap which has a small opening. This is to allow the trapped air to come out without spilling brake fluid all over.
4. Start the car, drive fast and brake hard to engage the ABS. Do this forward and backward several times as I showed in the first few seconds of the video below.
5. Brakes should now work as designed. Install original cap and enjoy the ride.
I read that idea somewhere else, and have done this a few times. I have a large yard with wet grass from the recent rain. I did around 20 hard stops from ~30mph, and I could feel the ABS pump in my pedal. This helped, but it's still not fixed.
I didn't do steps 2 and 3 though. It doesn't make sense to me that those steps would be necessary. I figured the air and the fluid would just exchange places, so I didn't see a reason for a vent. But I'll try anything now, I'll give it a shot and report back soon.
Bled 2 liters of fluid tonight. No bubbles. No improvement.
I've been trying to find a scan tool that can do a brake bleed on an ABS pump. I've purchased two different tools from two different manufacturers ($330 and $450, so not junk), and neither could do that task on my car. Before purchasing them, I called each manufacturer and asked which tool to buy for this exact task on this exact car. I bought what they told me to, and neither worked. I've emailed other manufacturers, and they don't respond. I've made posts on other forums asking what scan tool to get...nobody knows.
I think I'm giving up and taking this to the mechanic.
Last edited by ticklechicken; 09-28-2020 at 06:10 PM.
09-20-2020, 03:49 PM
brake bleeding help
