Pedal sink

[lovespaj]

I thought I would post here as its basically the same vehicle. I have out of the blue got some serious pedal sink going on. We have replaced master, booster and bled all lines, still the same. no fluid loss all calipers work. have separated each line and made no difference. Now we are stuck , pedal goes to the floor. No apparent vacuum leaks. Pedal hard when booster or car of. out of ideas....

[DibbyDibbyDJ]

Rear brake lines can be problematic to bleed on Triton. What year and model is yours?

[erad]

' Is the pedal spongy? It should not be that way, but if there is some residual air in the lines, when you apply the vacuum booster to it, that air will compress, even though it feels 'hard' without the vacuum boost.

Also, it there is no air in the system, and you have no external leaks, the fluid must be bypassing the seals in the master cylinder. If you have leaks somewhere, you will see them at the wheel cylinders, or at the back of the master cylinder, but it possible for the fluid to bypass the rear master cylinder seal (front brakes) and you still get pedal movement. This is unlikely though.

If the bore of the master cylinder is damaged (corrosion doe to moisture contamination) you could get bypassing of the seals in the master cylinder and the pedal will go to the floor.