ABS Pump Bleeding?

[SlashProm]

Replaced the brake line from the pump to the nearside rear axle union today. Pedal seemed fine but when I started it up the pedal is hissing and there is barely any resistance there. I've read there's a procedure to actuate the abs pump with VCDS? I only have the free version of VCDS Lite with the blue KKL Cable. Can I do it with this or will I need the full VCDS?

Or is there another way I could bleed the abs pump, like bleeding the brakes with the engine running or crack the abs pump at the union or something?

 

[RUM4MO]

I have a licensed copy of VCDS, but so far have never had to use the "purging ABS block" routine, so I can't comment there, though if you Googled doing that and could not get access to that routine in VCDS Lite then you would quickly get your answer.

I'm guessing that you did not try to minimise the flow of fluid out of the system by sealing the brake reservoir cap with something, or only used a pressure bleeder like Gunsons Easibleed? I've replaced many flexi pipes and never ended up in that situation.

 

[Rich.T]

Ditto^^^

Have you bled all 4 corners? Could be air in any of the other 3 pipes now.

Ive got a little tub of (new) brake unions of different sizes. Each one with a blob of silicone sealer in them to block the hole, basicly turning them into bungs.
Whenever i remove a brake pipe to replace it i screw one in to stem the flow.Then remove it when i fit the new pipe.
Works a treat and never had to bleed the other 3 corners.

Rich

 

[Yellow fr]

You can put a bar on the brake pedal with the brakes on then open the bleed nipple on the corner that you are replacing a pipe then that stops the fluid leaking out always
Have you also tried bleeding the master cylinder


Sent from my iPhone using Tapatalk

 

[SlashProm]

One of the unions wasn't fully tight. I only bled the back brakes but it's sealed up now. I'll just bleed the 4 corners. I was just wondering if I needed the abs pump on but it probably just needs a proper bleed at the 4 corners. I have an easy bleed so wont be too bad.

 

[RUM4MO]

Hah, my only a few years old latest Gunson's EasiBleeder let me down the other day, while flushing new fluid out of the 3rd calliper, I heard dripping noises, EsiBleeder not sealing well enough onto the reservoir, so a good hosing down with water was needed after I finished changing the brake fluid on my wife' 2015 Polo!

 

[SlashProm]

Still struggling with this bleeding. For some reason I can't get any fluid to come out of the nearside rear caliper. Even when I pump the pedal it's rock solid like the bleed nipple is still tight. Is it possible I have a blocked flexi to the rear caliper or something?

 

[Rich.T]

Crack the union off before the flexi and see what happens.

 

[SlashProm]

Ok. I've traced the problem back to the "ABS Pump Controller". I've cracked the top 4 unions and there's fluid coming out fine. I assume one is a feed and return to the reservoir and the other 2 are the feeds to the front calipers. I've cracked the 2 on the side, the feeds for the rear calipers and they are both dry, completely blocked for some reason. Brake pedal is hard which is weird as I thought the pedal would be soft if I had trapped air in the system.

Both back brakes aren't working at all.

 

[SlashProm]

*Update*
After a bit of research it seems that there are 2 valves in the abs pump for each caliper feed, an inlet and an outlet/dump. It looks like the outlets for the rears are stuck open. which will be sending fluid back to the reservoir and not to the calipers. Or the inlets are stuck closed, not allowing fluid up to the unions at all. I'll pull it off and see if I can unclog the valves. It's possible that after a few bleeds, the hard line being off for a week or two before replacing, as well as changing all the brakes, compressing pistons etc has drawn some moisture and or contamination into the abs unit. Worst case scenario I'll just have to order a second hand unit. Does anyone know if it needs coding to the car or is it just plug and play?

 

[SlashProm]

New ABS Pump on and finally got the brakes bled. The back brakes are a PITA to bleed. ABS Light is on, which is nothing new, as I've had a problem with the front right sensor needing replacing for a while now. So Usually the ABS light is constantly on as well as Traction control off. I went for a test drive earlier after bleeding the brakes. ABS Light is on, beeps at me like 4-5 times on startup and the Handbrake light is now flashing at me constantly. I also give the brakes a quick stab and one of the wheels locked up, which was surprising as I didn't slam on that hard or for very long, and it has 4 brand new tyres.

Does the ABS Module need coding when you replace it or will it just adapt? Thanks.