Is a VCDS Bleed Necessary???

[Samcrac`]

Hello,

I am almost finished fixing my 15 Audi S3. When I repaired my MK6 Jetta GLI, I did a standard 2 person brake bleed and the brakes were still pretty soft until I did a VCDS brake bleed. Now they are perfect stiff feeling VW/Audi brakes!

On the S3, my VCDS isn't working the same as it did on my Jetta, so I haven't been able to perform a VCDS bleed.

On both of these cars, there was an accident which damaged brake components. On my S3 I replaced the left rear caliper and I also believe the front left caliper was removed when I was working on the suspension.

I was under the assumption a VCDS bleed is 100% necessary to cycle the ABS pump which may have run dry or low on fluid. A recent discussion with someone told me there is absolutely NO reason to do a VCDS brake bleed, even if I completely replaced the ABS pump (which I didn't do).

Please let me know if you guys have any insight on this. Thank you!

 

[lou06483]

To bleed the ABS pump you need to PRESSURE bleed the system---VAGCOM cycling will NOT correctly bleed the ABS pump...Here's the rub- to bleed the abs pump a pressure of 2bar is required.That's nearly 30psi...I had this issue with my Audi S4...The problem is finding a cap that will hold that pressure-The cap supplied with my Motive Products bleeder would not hold and I had one made, in brass, at the model-shop where I work. With the new cap I was able to bleed the pump...
If you have a "good" pedal why are you concerned with bleeding the pump????
I had to bleed since I replaced the entire pump...normally I would simply pressure bleed at no more than 15psi, or 2-man, each caliber and call it a day.....HOWEVER- if you run the master cylinder dry and introduce air to the system then you will have to pressure bleed at the 2-bar level.

 

[Samcrac`]

To bleed the ABS pump you need to PRESSURE bleed the system---VAGCOM cycling will NOT correctly bleed the ABS pump...Here's the rub- to bleed the abs pump a pressure of 2bar is required.That's nearly 30psi...I had this issue with my Audi S4...The problem is finding a cap that will hold that pressure-The cap supplied with my Motive Products bleeder would not hold and I had one made, in brass, at the model-shop where I work. With the new cap I was able to bleed the pump...
If you have a "good" pedal why are you concerned with bleeding the pump????
I had to bleed since I replaced the entire pump...normally I would simply pressure bleed at no more than 15psi, or 2-man, each caliber and call it a day.....HOWEVER- if you run the master cylinder dry and introduce air to the system then you will have to pressure bleed at the 2-bar level.

This is awesome information. My pedal is NOT good. It's at least as not good as it should be. It works, is drive-able but not amazing. Do you know if one of these Harbor Freight style pressure bleeders using a standard air compressor is good enough for a pressure bleed?

 

[lou06483]

I've no experience with the HF bleeder....Try it-the worst that will happen is that the cap will blow off.Be sure to have a BUNCH of towels over the top of the master cylinder to catch the mess. Increase pressure slowly to the 30 psi level then proceed to bleed.
Have an assistant hold the towels in place when you do this. That will help keep the mess to a minimum should the cap fail to hold. If the cap blows and someone is holding the towels it's really not that bad--I had my wife do this for me. Scared the sh_t out of her

 

[Nuje]

Besides putting 30psi (2bar) pressure behind the pressure bleeder, is anything else required (like some sequence out of VCDS)? Or do you just pump up to 30psi, then go around and bleed the four corners?
(Replaced ABS pump a while ago and pedal has been mushy ever since)

 

[Cuzoe]

We need this information lol. I intend to replace my pump soon, following in Nuje's footsteps, or maybe his traps... Haha.

I've actually been looking at bleeders just for this project and I ruled out any that didn't have a picture of the gauge that was clear enough for me to see 30 PSI. On the other hand, it's sounding like some of you guys have bleeders that show 30 PSI but the cap won't actually hold it so I would like to avoid that.

I got my wife to come out and snug up transmission and engine mount bolts while I kept engine aligned but there wasn't much risk of getting dirty. I don't think she's going to hold any towels over the master to cylinder stop me from making a mess. But to be fair I don't want to deal with that mess either.

 

[Nuje]

Just for kicks, I've pumped my Motive bleeder up to max (on the gauge) pressure and the lid held on the reservoir.
Now, to be fair, I didn't leave it there for very long, so....???

My plan is to put the Motive pressure bleeder in a garbage bag, then just make a little tear in a corner to fit the bag over the reservoir, and then have a towel underneath everything. If it blows, the bag catches everything and there's only one place where the fluid is running down and (hopefully) being caught by the towel underneath.

 

[2019mk75gti]

To bleed the ABS pump you need to PRESSURE bleed the system---VAGCOM cycling will NOT correctly bleed the ABS pump...Here's the rub- to bleed the abs pump a pressure of 2bar is required.That's nearly 30psi...I had this issue with my Audi S4...The problem is finding a cap that will hold that pressure-The cap supplied with my Motive Products bleeder would not hold and I had one made, in brass, at the model-shop where I work. With the new cap I was able to bleed the pump...
If you have a "good" pedal why are you concerned with bleeding the pump????
I had to bleed since I replaced the entire pump...normally I would simply pressure bleed at no more than 15psi, or 2-man, each caliber and call it a day.....HOWEVER- if you run the master cylinder dry and introduce air to the system then you will have to pressure bleed at the 2-bar level.

So this sounds like what I’m going thru now.

I changed my brakes yesterday and bled for the second time (first time with a pressure bleeder) but the first time I did it I ran the cylinder dry by using the old school non pressure bleeder method.

ever since that first brake change my brakes seem to have reokn for improvement in the sense that they still stop the car , bite hard (ferodo ds2500 w/ stoptech rotors) and technically work well enough even for the track but they feel like they have more travel up at the top of the pedal than I remember.

currently I’m running stop tech rotors , ferodo racing pads , and castrol srf react , as well as stop tech stainless lines.
I would assume my pedal should me slightly more stiff than it currently is and wonder what I should just start with.
Abs bleed or 2bar pressure bleed.

I’ve also noticed that the front calipers don’t seem to have any air during pressure bleeding but the rear ones Will flow some fluid then have a batch of micro bubbles then more solid fluid.
Below are some pictures that show the fluid I’m getting out.
It looks good for 5-10 seconds like the first picture then I see bubbles like the second one.

the first picture is actually what my fronts looked like the whole time during the bleed but the rears would have pockets of bubbles like the second pic

 

[Golf R GT]

I've no experience with the HF bleeder....Try it-the worst that will happen is that the cap will blow off.Be sure to have a BUNCH of towels over the top of the master cylinder to catch the mess. Increase pressure slowly to the 30 psi level then proceed to bleed.
Have an assistant hold the towels in place when you do this. That will help keep the mess to a minimum should the cap fail to hold. If the cap blows and someone is holding the towels it's really not that bad--I had my wife do this for me. Scared the sh_t out of her

like he said I have a Mityvac MV6844, Motive and Branick G300 which we used at the dealer, to get a good pedal you need min 25psi. My Mityvac wasn't cheap but maxs out at 17psi and does not get my Brembo GT-S kit no where like the Brainick or cheap Motive

 

[Nuje]

I was able to get to about 27psi with a Motive pressure bleeder; it did the job with the bleeding and following the "fill" process in VCDS or ODIS. But to get the pedal to really firm up, I had to do the post-bleed process that's described in the manual.

 

[kevin ninja]

if you power bleed brake system up to 30psi and bleed one caliper at a time will this renew fluid in abs unit, or do i need to bleed both front then both rear calipers.car is vw golf gtd dsg mk7.5 uk car 2019

 

[Nuje]

If the ABS unit got air in it (e.g., it was replaced or pulled in air because fluid reservoir got too low), the only way to get all the air out is with the scan tool (VCDS).

 

[kevin ninja]

If the ABS unit got air in it (e.g., it was replaced or pulled in air because fluid reservoir got too low), the only way to get all the air out is with the scan tool (VCDS).

no air in system just want to replace all brake fluid in system

 

[Nuje]

Ahhh - good. If doing a simple flush, then, simply proceed from shortest to longest brake line (LF, RF, LR, RR).
Remember to do the clutch bleed as well if you have manual transmission.

 

[kevin ninja]

Ahhh - good. If doing a simple flush, then, simply proceed from shortest to longest brake line (LF, RF, LR, RR).
Remember to do the clutch bleed as well if you have manual transmission.

car is 7 speed dsg, will above method renew fluid in abs unit and this is done at 30 psi on each caliper