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· Registered
1 Posts
Discussion Starter · #1 ·
So my father and I have been trying for ages now to sort out his Discovery II 2004.

The problem is that the offside front and the nearside rear brakes will not, well, brake.

So here is what we have done;

Replaced Master Cylinder
Replaced ABS Valves
New Front Brake Caliper

Basically the brakes will not engage. We understand this is the secondary circuit in the ABS so our assumption is simply that there is a problem with the ABS.

We have bled through the brake fluid so many times you wouldn't believe but we are completely stumped why a simple brake bleed has become a trial akin to that of Hercules'.

We understand that the ABS has multiple solenoids in it perhaps one of these is stuck?

We did have the nearside rear brake working for a short period of time but we bled it through again and it stopped working again. SIGH.

Everywhere we have read people say that the Hawkeye is needed to completely get rid of the air in the ABS by activating the valves but we have managed to get a good pedal which doesn't go to the floor.

Help? :dunno:

· '03 Disco SE
573 Posts
This is a weird one. Can you describe how you determined that it was just those two calipers that weren't operational? Can you describe your brake bleeding method? Did you keep the reservoir topped up throughout the whole procedure? Do the calipers start to work if you pump the brakes repeatedly?

Logically, if you were able to successfully bleed the calipers at both the offside front and nearside rear by doing the pump-pump-hold method, then the system is working fine as the cylinder is allowing fluid to reach those points.

While I'm not excluding the possibility of a failed modulator, the valves fail "closed", meaning that even if you have a complete failure of the modulator, the brakes will still work without ABS capability, think "Three Amigos". Unless there was some serious error during the installation, I can't think of a scenario where the internal valves are binding. Are you sure you put it together properly?

Did you follow the correct bleeding order? For LHD vehicles the RAVE recommends FR, FL, RR, RL, but I've also used RR, RL, FR, FL and have been successful.

What I think happened:

1. There's still air in the system somewhere. Follow the correct bleeding sequence and continue it until clear fluid comes out. No bubbles or froth should be seen in the clear line leading from the bleeder screw.

2. Did you buy a new, used, or reman MC? It's possible that there is an internal leak in the cylinder that's minor enough to allow you to build pressure when you pump the brakes during the bleed, but that allow fluid to seep past during regular braking so that the calipers you describe aren't getting pressure.
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