Bleed Brakes with VCDS: A Step-by-Step Guide

Hello everyone,

"Unfortunately, the brake fluid reservoir in our Golf 7 has developed an air leak. I've read that in this case, it's essential to bleed the ABS system. Apparently, this can only be done using VCDS."

I've gotten this far:
- Brake electronics.
- Starting position.
- Bleed the brakes.
- First cycle.

When the first cycle is initiated, a loud noise occurs, and the vcds displays "Running." Subsequently, the noise disappears, and the vcds displays "Unknown."
It's likely that a certain order needs to be followed here as well. Are there any experiences with that already?

"Thank you!"
Best regards, Dennis.

[Translating...]

Autoscan?

I will submit it tomorrow today I didn't have the opportunity to do one.

Sorry for the delay, but here's the 3D scan of the Golf.

Hello,

There's an update available for your VCDS (same version, but with more recent data). This might resolve the issue with the text displays, as I recall there being instructions on what to do in those messages.

Best regards, Rainer.

Hello Dennis,

According to the manufacturer, a pre-pressure of two bar is required to bleed the hydraulic unit.

Manufacturer's recommended order:

1. vo. left.

2. from the right.

3. hi. left.

4. from the right.



Bleeding the ABS system using VCDS is only necessary if the ABS module has been replaced or if the system was completely drained of fluid. This type of bleeding is not required when replacing components (e.g., brake hose) or if there is air in the system.

Best regards,

Michael.

Good morning, everyone!

@Rainer: Thank you! I will inquire about the update. If I don't do the update once, there are immediately important things for me that are affected...

@Michael: I already had to replace the rear left saddle 3 months ago. That's when the BF container started drawing in air. This has never happened to me in 5 years . Since then, I've felt that when braking gently, you have to press the pedal more than 3 months ago, because the pedal always gives way a little bit until a certain point. Emergency braking still works, of course, but the brake used to be a bit more responsive when you lightly pressed the pedal.

I've already bled the system three times. I've rarely seen fresher brake fluid coming out of the calipers and clutch. That's why I suspect it's related to the ABS. On the other hand, I've also read that the hydraulic unit needs to be pre-configured.

Hello Dennis,

With a bit of luck, the good old two-man method of post-ventilation can lead to success.


A second technician is required for the post-ventilation process.

Connect the brake filling and bleeding device.
Apply and maintain firm pressure on the brake pedal.
Open the bleed valve on the brake caliper.
Press the brake pedal all the way down.
Close the vent valve when the pedal is depressed.
Slowly release the brake pedal.

5 x repeat.


It's likely that there's still a small air bubble trapped in the rear brake caliper. You'll only be able to remove it if you loosen the brake caliper again, allowing you to move it back and forth while bleeding the brakes, so that any remaining air can escape.

Ideally, insert an old brake disc or something similar between the brake pads to prevent damage and to avoid having to push the brake pistons back in.


Good luck.

Michael.

Hi,
A brake tester will likely reveal more. If a brake shows poor performance, it could indicate a possible air bubble in the (diagonal) brake circuit.
If the brakes are responding evenly, I would stop with the excessive bleeding.
hg
Herbert.

Hi!
If there is air in the braking system,
The brake can be pressurized.

You press the brake pedal once, and you notice how far it depresses.

Then, quickly depress the brake pedal 5 times in succession.
This compresses the air bubble(s), and the pedal becomes harder to press.

If you then wait for 10 seconds with the pedal released, the air expands again, pushing the liquid back into the container, and the pedal retracts further.

The description of the traditional German method for bleeding a cask, requiring two people, was accurate.
In addition, I would like to add that...
that you always need to pump the brake pedal three times before opening the bleed valve.
It slightly increases the effectiveness and the likelihood of success.

That's how I learned it during my apprenticeship, and that's how I've always done it.

And yes, there are cars where it's simply the only way to do it.
Man kann nicht unendlich Druck auf den Behälter geben, weil der dann auch mal platzt. Sure, here's the translation:

"A bar, maximum."

I once owned a Lancia, and that wouldn't have been enough.

Quote:

...If there is air in the braking system, The brake can be pressurized. You press the brake pedal once, and you notice how far it depresses. Then, quickly depress the brake pedal 5 times in succession. This compresses the air bubble(s), and the pedal becomes harder to press. If you then wait for 10 seconds with the pedal released, the air expands again, pushes the liquid back into the container, and the pedal goes back in...

Exactly!
And if that doesn't happen, it's probably because there's no air bubble inside.

Herbert.

Hello everyone!

"I can hardly imagine that there's air trapped in a brake caliper anymore. I've bled all the calipers thoroughly twice. It must be either the ABS system or the hydraulic block that's causing the problem."

@Ich_Can_Nix: You mentioned that a pre-charge pressure is needed for the hydraulic block. In that case, VCDS alone won't be very helpful if you don't have a compressor for it. Or does the system build up the pressure itself when activated?

Greetings!

Hello Dennis,

Your car scan suggests it originates from the homeowner. If that's the case, please update your account accordingly.

Generally, support is only available through an account.

Regarding your question:

According to VAG, the Golf VII requires a pressure of 2.0 bar at the VAS 5243, which is the hydraulic brake bleeder.

If you want to do it "right," you'll need a brake bleeding device with a connection for compressed air.

VCDS supports the process of bleeding. However, VCDS alone will not guarantee success.

I wouldn't ignore Herbert's suggestion – a brake test on a dynamometer will show you whether your perception matches reality.

From my experience, if brake calipers from the aftermarket are installed and not filled with brake fluid before installation, problems can occur.

The problem might be that a small air pocket is forming above the bleed screw. You won't be able to get rid of that air bubble, even with 2 bar of pressure.


Best regards,

Michael.

Hi,
The filling pressure of 2 bar is not the determining factor; it can also be achieved with 1.5 bar or even 1 bar.
For the Golf 7, there is an additional procedure for bleeding the brakes (in cases of excessive pedal travel or a spongy brake pedal). Instead of simply opening the respective bleed valve after connecting the filling device, the procedure essentially involves building up the correct pressure with the brake pedal.
Do you have the guide? It's described in detail there.
hg
Herbert.