Looking for any pointers or suggestions. Brake pedal sinks to floor with the engine running after brake lines and bleeding.
2002 Audi A3 1.9tdi quattro sport
Was working ok.
New OSR brake calliper
New NSR brake hardline/flexi
New OSR brake hardline/flexi
OSR inner flexi was clamped, calliper line removed and left over weekend as wrong line supplied.
New OSR brake calliper fitted
New OSR brake line fitted
New NSR brake line fitted
Bled rear brakes with the engine off, fluid came through clear, pedal feel good.
Turned on engine, brake pedal slowly sinks to floor if you keep pressure on it.
Turn off engine, brake pedal solid.
Bled rear brakes again
Bled all brake callipers
Bled master cylinder
Fitted new bleed nipples
Bled ABS pump
Bled all brakes
Bled ABS pump
Bled all brakes
Bled all brakes/master cylinder
Pedal still slowly sinks to the floor with the engine on if you keep pressure on it.
No visible leaks for brake lines/components, no signs of swelling flexis. No fluid loss (reservoir level does not drop)
Brakes were bled NSR, OSR, NSF, OSF manually with 2 people, down, open close, up repeat. ABS pump was bled through VAG COM following instructions on screen, solid fluid out both callipers, no air.
If you disconnect the servo vacuum the brake pedal feels fine, but no assist.
Current thoughts are the master cylinder seals may have been damaged/flipped after travelling the full length of the bore whilst bleeding, if there is a step worn, or a corrosion spot in the bore that is not usually swept? With the engine off the fluid bypass is so little you cannot notice it, but with the engine on the servo forces the fluid past at a noticeable rate?
Any thoughts or experiences would be appreciated.
(I think I am just trying to avoid changing the master cylinder )
Thanks
2002 Audi A3 1.9tdi quattro sport
Was working ok.
New OSR brake calliper
New NSR brake hardline/flexi
New OSR brake hardline/flexi
OSR inner flexi was clamped, calliper line removed and left over weekend as wrong line supplied.
New OSR brake calliper fitted
New OSR brake line fitted
New NSR brake line fitted
Bled rear brakes with the engine off, fluid came through clear, pedal feel good.
Turned on engine, brake pedal slowly sinks to floor if you keep pressure on it.
Turn off engine, brake pedal solid.
Bled rear brakes again
Bled all brake callipers
Bled master cylinder
Fitted new bleed nipples
Bled ABS pump
Bled all brakes
Bled ABS pump
Bled all brakes
Bled all brakes/master cylinder
Pedal still slowly sinks to the floor with the engine on if you keep pressure on it.
No visible leaks for brake lines/components, no signs of swelling flexis. No fluid loss (reservoir level does not drop)
Brakes were bled NSR, OSR, NSF, OSF manually with 2 people, down, open close, up repeat. ABS pump was bled through VAG COM following instructions on screen, solid fluid out both callipers, no air.
If you disconnect the servo vacuum the brake pedal feels fine, but no assist.
Current thoughts are the master cylinder seals may have been damaged/flipped after travelling the full length of the bore whilst bleeding, if there is a step worn, or a corrosion spot in the bore that is not usually swept? With the engine off the fluid bypass is so little you cannot notice it, but with the engine on the servo forces the fluid past at a noticeable rate?
Any thoughts or experiences would be appreciated.
(I think I am just trying to avoid changing the master cylinder )
Thanks
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