Bleed brakes with VCDS

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. It seems that's only possible via vcds.

I got 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."
Most likely, a certain order needs to be followed in this case as well. Are there any experiences with this yet?

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 is an update available for your VCDS (same version, but with a more recent data set). Perhaps this will solve the problem with the texts, because, if I remember correctly, each one included instructions on what to do.

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: Thanks to you! I'll look into the update. If I don't do the update once, there will immediately be relevant things for me included...

@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 you brake gently, you have to press the pedal more than I did 3 months ago, because the pedal always gives way a little bit until a certain point. Emergency braking systems work, 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 fresh brake fluid coming out of the bleed screws and the clutch bleeder. Therefore, I suspect it's likely an issue with the ABS. On the other hand, I've also read something about the hydraulic unit needing to be initially configured.

Hello Dennis,

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


For post-ventilation, a second... Technician needed.

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.
Release the brake pedal slowly.

5 times.


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

Ideally, insert an old brake disc or something similar between the brake pads to prevent damage and to allow the brake pistons to be pushed back.


Good luck.

Michael.

Hi,
A brake test likely reveals more. If a brake shows poor performance, it may indicate the presence of an 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 can be depressed.

Then, quickly depress the brake pedal five 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 fluid back into the container, and the pedal moves further down.

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 brakes 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.
You can't apply infinite pressure to a container, because eventually it will burst. Sure, here's the translation:

"A bar, maximum."

I once owned a Lancia, and that wasn't 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 can be depressed. Then, quickly depress the brake pedal five 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 again. ..

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

Herbert.

Hello everyone!

I can hardly imagine having air trapped in a saddle anymore. I've thoroughly bled all the saddles twice. It must be either the ABS or the hydraulic block.

@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 it's activated?

Greetings!

Hello Dennis,

Your car scan suggests a connection to the homeowner. If that is the case, please update your account.

Generally, support is only available with a corresponding 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 bleeding process. VCDS alone does not lead to 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 may be caused by a small air pocket 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 2 bar filling pressure is not the determining factor; it can also work with 1.5 bar or even 1 bar.
For the Golf 7, there is an additional guide for bleeding the brakes (in cases of excessive pedal travel or a spongy brake pedal). After connecting the filling device, the respective bleed valve is not simply opened; instead, pressure is built up correctly using the brake pedal.
Do you have the guide? It's described in detail there.
hg
Herbert.