Hi all ive just ordered a new brake master cylinder from tps and just need to know whats all involved doing the replacement do i really need vcds for abs pump or could i just not install new part and let fluid to all brakes and bleed just like the old school way many thanks

Anyone?

You could fit and carefully push caliper pistons in to reverse flow the fluid until it enters the reservoir free of air, apply brakes keeping reservoir topped up and away you go.

Tricky but doable.

If you just whack the new master cylinder in, top up the reservoir and use the brakes you'll probably end up forcing trapped air into the ABS pump which will give you a spongy pedal and ineffectual stopping.

Then you'll need to activate the ABS pump via the OBD port and bleed calipers.

You can also try hard braking on loose/slippery ground to activate the ABS and then bleed the calipers... I'm yet to be convinced this actually works, by the time you get to the bleeding, any purged air has travelled back into the pump.

Thanks for your reply ok i could try it that way i have a delphi ds150e scanner tool not a genuine delphi but a copy one would this be able to purge the air from the abs pump like you say thanks for the info

Edited 1 January, 20179 yr by octaviatdi02

I've no idea, I've been fishing for a cheap way to activate the ABS pump myself and so far nobody's recommended anything bar VCDS.

I had thought of having both front wheels off the ground on axle stands and running them up in gear and seeing if the ABS can be activated by applying the brake.

If it works it would be a cheap way to purge the system, then again if the wheels are individually sensed it would depend on which wheel the ABS is activated on so maybe not ideal.

I have seen them purge the ABS in a garage and I'm confident they were able to select which wheel to work on rather than system wide.

Yea would be handy if it worked but i think with the wheels of the ground the abs and traction controll system would not function as it should as the abs and esp light probibly would come on resulting in the abs/esp system not to work pity thers not a guide or simple way to do it

Santa wasn't forthcoming with a £20 Chinese wonder box to do the job.

If you find a cheap solution let us know, there are many of us DIY types who loathe paying a garage to do this simple procedure or paying as much if not more for an all singing, all dancing solution.

You could use a pressure bleeder they are cheap enough and easy to use I work in a German car specialist and have never needed vcds even though we have it

Ive just ordered a sealey vs820 brake pressure bleeder and i will give that a go i hooked the delphi copy scanner up this evening and im glad to see it will bleed the abs pump great tool hasnt failed me yet compared to the real expensive scanners out there as ive used vag com and snap on solus pro previosly and the delphi copy scanner in my opinion is a hell of a lot better maybe its just my imagination lol daddyno1 which pressure bleeder do you use if you dont mind me asking thanks

Edited 2 January, 20179 yr by octaviatdi02

I use a Gunson eezibleed pressure bleeder.

It's ok for general bleeding but it won't purge any trapped air in the ABS pump, that requires... the tool!

I use a Gunson eezibleed pressure bleeder.

It's ok for general bleeding but it won't purge any trapped air in the ABS pump, that requires... the tool!

If you don't have VCDS, there is a more labour intensive way to purge the system.

 

- Bleed the brakes as normal using a pressure bleeder as that should get rid of most the air. 

- Put the wheels back on and take it for a drive, where safe, do some aggressive stops to cycle the ABS pump. Be warned, the brakes may be spongy so drive accordingly.

- Re-bleed the system using the pressure bleeder.

 

There is still a risk that some air will remain but it should do a better job than just bleeding the brakes, you can also repeat if needed.

 

Where in the UK are you? A local member might be able to pop by with VCDS :)

Cheers for that info im in northern ireland will give it a go today

P.s will it be ok to bench bleed the master cylinder as i see theres a sensor on the cylinder for the esp i think

If it's anything like the Ate master cylinder on mine, the sensor as you call it is just a magnetic switch that detects piston movement and activates the brake electronics i.e. brake lights/ABS etc.

Micmac yes as you say must work magneticly as it just bolts to the side of the master cylinder did you bench bleed yours

I didn't bench bleed mine, on the assumption that you'll always get a small amount of air trapped between pipe fittings and cylinder no matter how careful you are so why waste time.

Assembled dry and filled with fluid, brake pedal depressed lightly and slowly repeatedly to work any trapped air back up through the piston then pressure bled after test drive.

It is important to note that brake pedal movement was not sufficient to actually apply brakes rather just exercise the fluid/air in the lines and allow trapped air to rise up and out of the cylinder.

Thats great thank you for your help mate much apreciated i will do that cheers

No worries you're welcome I hope it works out for you.

Thanks i will update with how i got on hope the chinese wonder box does the bleed process ok lol cheers

Hey all just an update got the car all finished up today used the copy delphi scanner and waow id recommend to anyone who needs to bleed the abs pump great piece of equipment for very cheap money compared to vcds and so on big thanks also to MICMAC for your help.brakes have never been as good also the sealey vs820 is a must i should of bought one years ago no more pumping at brake or clutch pedals for £44 is defaintly worth buying hope this helps someone PS the amount of air that gets trapped in the abs pump is unbeliveable firstly i blead the system with pressure bleeder like normal open bleeders ect until there was no air plugged in the diagnostic scanner and done the abs bleed process there really does be quite a bit of air in that pump cheers everyone

we have a sealy pressure bleeder ive very rarly  used a diag machine to bleed brakes unless it has a power brake system like a super car or amg speck merc we specialise in all german cars and replace vag abs pumps regularly as it is a common fault the only car ive had to use diag tool on is the bmw sita tool on m series like m5 or m3 but never vag