ABS Bleed Question

Lex4TDI4Life

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2001 Golf-Ute TDI GLS 5spd Manual
Happy Thanksgiving! Having nothing better to do today, I'm going to bleed my abs controller because I still have a soft brake pedal after swapping calipers.
I have read over a number of threads detailing how to bleed the system with vcds. I have seen conflicting information, however, when it comes to whether to have the bleeders open or closed when pumping the brakes 10 times.

Simply put, should the bleeders be open or closed when pumping the brakes 10 times?

TIA,
Lex
 

Lex4TDI4Life

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Answered my own question. It appears to be pump 10 times AFTER closing the FR and FL bleeders. At least, now that I have done it, my pedal is much firmer.
 

golfclub

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Victoria B.C.
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2000 TDI Golf
This question has been asked on the forum for many years. And the best I can gather is that
we come up with our own approach to it.
I was was thinking about the output test. My thinking is that it is a functionality test only
and that no fluid moves through the ABS unit if the bleeders are closed. Please correct me
if I am wrong. If no fluid moves then is it fair to say that no trapped bubbles would move either?
But maybe it can circulate fluid somehow, I don't know.
I also don't think you would need to do 10 ABS bleed cycles with the front bleeders open. One or two
should be enough to move fluid and bubbles through to the wheels.
Again please correct this if wrong. I am planning to do this soon.

Thanks

Peter
 

T-Roy

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Virginia
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'92 ECOdiesel AHU
Man so many people have this issue / question and after much research I still don't have a clue the "right" way to do this job.

Add me to the list of someone who bought a car with mushy brakes, put all new stuff on and pressure bled with 2 people, but still have to push the pedal more than normal and just general "inconsistencies" while braking. Definitely feels like a little air in the lines somewhere. It isn't dangerous, but it also isn't really right or confidence inspiring. I really don't think there is anything wrong with the MC or booster from how it acts.

It seems there really is no 100% consensus on exactly how to do the ABS pump / VCDS bleed procedure unfortunately.
It is all just "this is how I do it and it has worked for me" sort of information, but the way people do it is all different lol.
Every thread / post / youtube you find manages to contradict each other.
Only thing really left at this point is to just dive in with a gallon of brake fluid and see if I can make it better by trying possibly multiple ways of doing it.
Driving from Virginia to Texas in a few weeks and will be tackling this with a helper (my dad) and hopefully a bit warmer weather over the holidays down there.
 

STDOUBT

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Portland, effing Oregon
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dos jettas
but the way people do it is all different lol.
Even the Bentley manual says it's not a problem to do it either "manually" (the old-fashioned way with a buddy) or by using a pressure bleeding technique. Of course, fancy shops will have regulated air, and a guy in his driveway will have a 1 gallon air pusher thingey.
Bentley does state "Pressure bleeding, if the equipment is available, is the fastest and most complete way of bleeding the system and is the factory preferred method."
And as for the ABS pump activation process, it's a nice thing to be able to activate and flow fluid through the ABS, but think about it.
Once clean, air-free fluid is throughout the system, there can be no good reason to keep exercising the pump. Especially by letting it push out more clean fluid to waste.
Think about the end goal.
Clean, air-free fluid throughout the system. How you get there doesn't really matter.
 

Lex4TDI4Life

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@T-Roy Amazing that there are still mysteries about these machines after almost 25 years of service :)

@STDOUBT The procedure you are referring is for bleeding the lines generally and, yes, either pressure bleed or bleeding by foot is fine. And the order is based on the model of ABS controller in your car, which you can determine by looking at the control module in VCDS.

My question is about the ABS module bleed procedures, which must be done through VCDS (you can see a description here https://forums.tdiclub.com/index.ph...-abs-pump-through-vag-com.255349/post-2655853). At one point in the process, VCDS instructs "DEPR. PEDAL 10X BLEED SCREW CLOSE." This is obviously not a complete, coherent sentence, so there is some debate as to whether to close the bleeders (only the fronts in this case) before or after pumping 10 times. It makes little sense to me to pump with the bleeders open as you will be drawing air back into the lines every time you release the pedal.

I went through three cycles of the procedure and the pedal feel seemed to improve, but it was kinda squishy again when I took her out today. Maybe some more cycles are necessary. Or maybe I am 100% wrong and need to keep those bleeders open during the 10x pump!
 

Nuje

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At one point in the process, VCDS instructs "DEPR. PEDAL 10X BLEED SCREW CLOSE." This is obviously not a complete, coherent sentence, so there is some debate as to whether to close the bleeders (only the fronts in this case) before or after pumping 10 times. It makes little sense to me to pump with the bleeders open as you will be drawing air back into the lines every time you release the pedal.
But you do this with the pressure bleeder pumped up to 15psi, right? So, there's no way air is getting sucked in via the bleeder screws with 15psi behind them.

The thing that finally firmed up my brakes after messing around with the VCDS procedure and pumping untold litres of fluid through it, came from one of the senior techs at my local VW shop. He pointed out that once the ABS is activated, it's basically aggressively stirring the fluid, so all sorts of little bubbles form if there's any air in there. The secret, he said, was after you've done that, go for lunch, grab coffee, clean up the garage - do something else for 20minutes or so. Give it time for all of the micro-bubbles to coalesce into mega-bubbles, then do your final bleeding, preferably the two-person method.
Gave that a try and it worked perfectly - both on my mk4 and Mk7. Good solid brake pedal.
 

Lex4TDI4Life

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Jun 22, 2006
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NorCal
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2001 Golf-Ute TDI GLS 5spd Manual
Interesting. I saw no mention in the various threads about having the Motive attached and pumped up while doing the VCDS procedure.

Either way, makes sense to do another final bleed after bleeding the ABS.
 
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