Brake Master Cylinder Help

[thomas574]

So I just bought a 04 audi A4 1.8t base that has no brakes. The peddle would go to the floor and the original owner claimed it was the master cylinder. So I went ahead and ordered a new Mc following a guide on how to install.

Couldn't remove the MC without unbolting the booster box. I basically had to loosen the bolts then tilt booster to pull out mc. I was told to bench bleed the new MC which I did off the vehicle, but could NOT rebolt new MC back in without removing the reservoir to get to the brake lines and the bolts for the booster and mc.

I did plug the reservoir holes temporary while I got the brake lines connected and mc/booster bolts in, I hope it didn't let more air in. Popped reservoir back in and peddle still goes to floor while pumping brake peddle a little.

I'm sure I still need to bleed the brakes but have no pressure bleeder, I did buy a kit from harbor freight not sure if this will work. https://m.harborfreight.com/brake-fluid-bleeder-92924.html

Also I see lots of people saying to bleed brakes FL, FR, RL, then RR. Then I also see some saying RR, RL, FR, FL so which is correct?

[A4-Mike]

Always start at the wheel furthest away from the MC and work towards it

02 A4 B6 1.8TQ Stage 3

[B6 Oxtail]

I mean, you can always try gravity bleeding them in that ^ order first n see if that works.

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[thomas574]

So I did the gravity bleed and now I have some brakes but not much, also the abs and brake light flash do you think there is still air in the system?

[B6 Oxtail]

How does the pedal feel??

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[B6 Oxtail]

And is the abs actuating though? Or its just the lights?

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[KHARDa4]

Bleed, bleed, and bleed again. I used pneumatic bleeder when my brake line went. I could not get a good pedal. Thr car would stop but pishing the pedal had a delay before the brakes would grab. The power bleeder only got me so far. What ended up working for me was repetitive manual bleeding. I must of bled the reservoir 1-2 times for each caliper. I used a bottle to catch the fluid to put back in the reservoir so you're not wasting fluid. Each cycle was majority a solid stream, I saw a very small amount of bubbles at the caliper, nothing that would make me think it was anything other than air. I ended up going the route you did thinking i had a failed MC. Replaced it and pneumatic bled with little to no help. Eventually after many many bleed cycles i got a hard pedal. I've never experienced a vehicle that was this hard to bleed. Even when i installed my b6 s4 calipers all around i didnt jave any of these issues. If air gets in the ABS control module it is a pain to get it out.

[thomas574]

brake pedal gets some pressure only when car is off, When i turn it on it goes to the floor. When i first start car brake light is always flashing and if i drive it for a little Abs stays on. Also when i first start car i can hear the brake booster vacuum pump start but then cuts right off. I press pedal it still doesn't turn on. I checked Codes with vcds and found it had P1479 when i clear code it never came back so far. I ran test with Vcds measured block 008

with car on I get
Not open/pump off/450.0Mbar

Car on pressing brakes
Activated/pump off/460.0Mbar

Car off I get
Not open/pump off/975.0Mbar

Car off pressing brake
Activated/pump off/985.0Mbar

Not sure if that's normal for the pump to stay off always?

[old guy]

If the pedal goes to the floor you still have have air in the system. Keep bleeding.

[Turbo510]

If there is air in the ABS unit, and there probably is, the ABS pump needs to be run to force that air out. VAG-COM.