Originally Posted by MikkiJayne (Post 149179)

That is the exact symptoms of when I had a master cylinder fail due to the scenario I described. One circuit (ie one half of the master cylinder) failed so I had no brakes on FR and RL (or vice versa) and then once the pedal had almost reached the end of its travel, it braked on the other two wheels.

The brake fluid reservoir will take 2 bar if its not cracked or damaged. It'll expand quite alarmingly, but I haven't had a D2 one pop yet! You'll not push fluid through the ABS pump at 10psi.

Originally Posted by HPsauce (Post 149180)

Diagonally opposed cylinders linked are part of the standard design of braking systems to ensure total failure is extremely unlikely. And have been for decades.

So the symptoms are to be expected from almost any braking system going wrong, the challenge is to work out exactly what the cause is.

Originally Posted by MikkiJayne (Post 149183)

Do one at a time. There is a specific order which I can never remember. I'll look it up.

Fingers crossed its just behaving like this because you have a load of air in the system +++

Originally Posted by MikkiJayne (Post 149186)

That looks right.

I did explode the reservoir on an A4 a few years back. They catch sunlight through the back of the bonnet and so the back of the reservoir was crazed from UV damage. I hooked the pressure bleeder up to it and it blew the top right off! I had to push the car outside and hose it down to get all the brake fluid off.

The D2 reservoir is completely covered by the bonnet though, hence why they have less tendency to blow up :)

Originally Posted by MikkiJayne (Post 149198)

Are you getting fluid from the other corner?