Any help would be greatly appreciated.

Ill do my best to explain....

The brake pedal is hard, or goes straight to the floor before the engine is started

Once driving, around 30kph there is a thud and the car slows as the front brakes start to bind.
If I loosen a brake pipe on the ABS the brakes release and I can drive but the brakes then are really bad. Either straight to the floor or very spongy

I have changed the master cylinder for new and a second hand abs. No difference.

When I bleed the front brakes they bleed as normal.
When I bleed the rear brakes even with the valve open the pedal remains hard and no fluid squirts out.

I'm at the stage now where I am defeated!!

I’d be looking To the ABS PUMP or a kink in the rear pipes, have you taken off the rear flexi pipes to see if anything drips out? 2004 Autobiography TD6 Java Black

Those symptoms do sound a bizarre combination !
"Automatic braking" ar 30 kph would suggest that either the ABS is operating to pump the brakes on or that the mastercylinder is already beyond its "vent" or open position or ABS valves are shut & heat in the brakes is creating pressure in the system.
I would expect if the ABS is operating, you'd feel it through the pedal as the pump operates - but am not sure.

When you say the pedal goes to the floor before the engine is started, do really mean right down to the carpet ?
If yes, it would probably suggest both circuits are leaking within the mastercylinder. - which is unusual unless the system has been contaiminated by petrol or engine oil.
If it only goes part way down, potentially only 1 circuit is effected.
If you start the engine with your foot on the brake pedal, what happens ?

Have you tried pushing the brake pistons into the calipers at each end ?
If the mastercylinder & ABS valves are working correctly, you should be able to push fluid back through the ABS modulator & mastercylinder into the reservoir.
If you can't, from any caliper, it would suggest a circuit is blocked - either by ABS valves, mastercylinder seals or kinked brake pipes.
If you can push fluid back with the engine off, try again with the engine on.
If you can't now push fluid back it suggests the mastercylinder is being pushed forward via vacuum in the servo - indicating either a bad servo OR maybe poor setting of the servo output rod.
I've never come across ABS units doing bizarre things yet on other makes of vehicle - but as this is an RR, who knows - lol.

Good luck ! Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 151,000 miles & now sold
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Thanks for the comments.

Ill try to answer the all .

Yes sometimes the pedal goes to the carpet before I start the engine

The master cylinder has been replaced with a new one
The and has been swapped out with a working used part.
If I start the engine with the pedal down nothing happens. No movement or resistance.


I'm thinking there's no return to master cylinder that's the reason the brakes bind. Ill try the caliper today and see if it pushes fluid back.

Could be the master is faulty, even second hand parts sold have to work if you bought it as working, if you bought it from a reputable sellers ask for a swap

The master cylinder is a new one, the ABS is second hand.

I would suggest that you change all four of the rubber flexible brake hoses.

I have known them to fail, but look ok externally, such that they collapse internally in a way that lets high i.e. braking pressure to pass fluid through, but doesn't allow sufficient flow to return from the caliper to allow the pads to release cleanly from the disk.

This would explain why you're struggling to bleed the rears. Pedal to the floor is the pipes swelling as they expand.

I've wondered whether the problem has been caused by the use of hose clamps to shut off a line for servicing, but have no proof of this.