Brake problems, end of my tether, please help

[stevec2910]

I have a 2011 maxi and having brake problems that no-one can seem to fix. Used 3 different mechanics, but still not solved.
Brakes a fading due to some how taking on air. I have had the whole system pressure bled, and three master cylinders on (incl the original). The system bleeds up well with an excellent peddle and brake performance, however with use over around a week, the brake fades badly up to the point where the peddle goes to the floor and it is unsafe to drive. The system does not lose fluid, but is taking air from somewhere, which from the last two goes appears to be at the front.
Really not sure where to go from here, this vehicle is required daily and three different people have give up on me. Help please.....

[Doc]

Hi @stevec2910, welcome to the forum.

Pressure bleeding is not always the best method for getting rid of air in a brake system, it can unintentionally introduce air if you are not careful.
I'd suggest you bleed the brakes the old fashioned way, pumping the pedal, holding and then releasing the pressure from the bleed nipple one wheel at a time.

Seeing as you've taken it to three mechanics, I'm going to assume they have a diagnostics system which can properly cycle the ABS pump to bleed out any trapped air? If not, they shouldn't really be working on vehicles with ABS but that is besides the point.

Have you any signs of weeping fluid on the system? MC, ABS, at the transition from solid to flexi in the arch, on the calipers?

What fluid is being used, it is the correct DOT rating and not mixed?

[John M]

ABS pump.....

[stevec2910]

Hi no leaks, but not heard of using a diagnostic tool to bleed the ABS Pump. I have no warning light on the ABS, and it works.
How does using the diagnostics to bleed the ABS Pump work, so i can discuss this in person to the next person i take the van to. Cheers Steve

[Tox]

Any resolve on this ? I have the same issue and the mechanic is saying potential abs block is causing air to get into the system.

[James01]

I had a customers van that used to lose pedal about every month, we tried new master cylinder but that didn't fix it fitted second hand abs pump and has been fine for the last 8 months

Sent from my SM-A505FN using Tapatalk

[VanLife]

+1 on the ABS pump.

If you bleed the brakes with the engine running it will also bleed the ABS pump so no need for diagnostics and can be done at home.

[tek199]

@VanLife
had this issue with 04 Polo. I tried diagnostic bleed with mixed success but also came across article where you had to activate ABS to remove trapped air.
Ie drive at moderate speed, mash the brake pedal (after checking rear view mirror) on wet or gravel road until ABS activates. Repeat few times. then go back to each caliper and gravity bleed.

Lastly I assume your mechanical stuff was serviced to make sure front calipers rear brakes are adjusted and sliding easily etc.

[tek199]

Hi no leaks, but not heard of using a diagnostic tool to bleed the ABS Pump. I have no warning light on the ABS, and it works.
How does using the diagnostics to bleed the ABS Pump work, so i can discuss this in person to the next person i take the van to. Cheers Steve

VCDS activates the ABS pump on each circuit while pressing the brake pedal. I used my mate to open the bleed nipples for corresponding wheel at that time.

[jjdunphy]

I have this too, literally exactly the same. 2011 maxi 1.6 ex BG.

Did you sort it in the end, or have I somehow ended up with your van haha

[Skezzer]

I have the same issue:

Spongy brakes, ABS reconned, spongy again,
Master cylinder replaces, spongy again, callipers (2) replaced. Still going spongy.

What’s going on!? Brake fluid blowing back so def air in system

Any help would be appreciated. They want to send off ABS pump again to rule out

[Stumpmagnet]

defo ABS pump, had this on my old 06 1.9tdi it would draw in air but not loose any fluid, bought a reconed unit off a place in ireland via ebay and solved the problem, just need the mechanical part with the valves not the electrical actuator part

[oOInSaNeOo]

i had a 2012 caddy in recently with this fault previouse garage fitted a second hand master cylinder badly so refitted the master cylinder properly and bled the system, using vcds to activate the pump and was still the same. i had this van for a week i clamped every flexi and removed them one at a time after a day to settle but the van peddle only fadded after a few hours of use. i had no evidence to suggest an abs pump union leaking or drawing air and took the plunge got the customor a second hand abs pump and used his electrical module portion so no recoding was needed and bled it again. van has since been fine that was maybe 2 month ago. hope this help i had checked everything twice before comiting to the pump