Help please problem bleeding 110 with ABS new brake master cylinder

TD5 110 XS, so factory fitted ABS. I bought a Delphiaftermarket LR013017 brake master cylinder, as brake pedal would go to floor with no loss of fluid. The cylinder I removed had a plastic housing around the pushrod, but the new one does not. There is also an O ring supplied in the kit with no obvious place to fit it. Fitted it anyway, everything else seemed correct.
Problem bleeding system: air bubbles up in rear section of master cylinder when pedal is released and I cannot get air free fluid from front bleed nipples, seems frothy at times.
I have looked in forums but cannot find identical problem. Have looked for a complete exploded diagram of servo/cylinder but cannot find one.
I can buy and fit a different 013017 with the plastic cap, which may sort it, but I would prefer to understand what is going on.

Have I missed something? All help gratefully received.

PS I have just bought an Eezibleed to help fluid flow.

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Are you sure the master was at fault?

I had a similar issue a while back, fitted a TRW master and after bleeding the pedal was rock solid with almost zero movement and barely any braking force. Replaced it and it was fine, the unit was faulty. Ive found alot of TRW parts being faulty recently.

If you have a nanocom you can use the power bleed function which can expell any remaining air.

Show some pics of the old unit and new unit.

Also.are you certain its a master for ABS? They are different to non ABS

Hi and welcome.

bankz5152 said:

Are you sure the master was at fault?

I had a similar issue a while back, fitted a TRW master and after bleeding the pedal was rock solid with almost zero movement and barely any braking force. Replaced it and it was fine, the unit was faulty. Ive found alot of TRW parts being faulty recently.

If you have a nanocom you can use the power bleed function which can expell any remaining air.

Show some pics of the old unit and new unit.

Also.are you certain its a master for ABS? They are different to non ABS

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Hello, and thank you for reply. It's really good to know that somebody is there.
The brakes deteriorated quite suddenly. The point at which the pressure started was much lower than previously and it was not "solid", the pedal could be pressed to the floor if I continued. There was no loss of fluid.
The cylinder that I received is a Delphiaftermarket as shown below and the one that I took off is the same as the one that you had for sale in May 2022, the one with plastic housing on the pushrod. Both are listed as suitable for cars with ABS: Part number LR013017. I do not have a Nanocom. Do you still have that cylinder? I am still puzzled as to where the extra o ring is supposed to fit - I don't suppose you have any info on that do you.