brake pedal sink ML

[mikeyoda]

Ok guys here goes,

Brakes were working spot on, then at one intersection miles from home brake pedal went to floor after stopping,
I believe its called brake sink...
And its been that way ever since, 90k on the clock.

So far..

All Calipers checked ( all good)
All lines checked nothing found
No vacuum or fluid leaks found
Replaced master cyl.
Replaced booster.

I mean its the brakes , how hard can it be, 3 mechanics later no resolve,
Pedal still goes to the floor after she stops.

The only thing noted was after 3 containers of brake fluid and much bleeding , the last thing we tried was to bleed the brakes while running. To our surprise some air came out the right front. The pedal still sinks but not as fast.

So I am wondering if there is a special bleed process? or any ideas, because at this stage I may drive it in a lake or tree.

thanks collective wisdom...

[DibbyDibbyDJ]

Are the rear shoes adjusted correctly?
Have you bled the ABS unit?
The rear brakes can also hide air in the flexible piping and pipe across the axle. I normally use gravity to bleed brakes when doing fluid changes, but if a component has been changed you need some pedal action. Slow presses with not too much force.

[mikeyoda]

thanks, is there a way to bleed the abs unit?

[DibbyDibbyDJ]

Only by undoing the outlet pipes on the body whilst someone pushes pedal. Treat them as a bleed nipple. Then do the individual wheels afterwards.

[mikeyoda]

thanks

[mitzi1]

Mate years ago I had an old tin landrover, the old 60's type. Tried to bleed th brakes for hours just like you have. Was talking to an old english bloke who loved them. He said it was easy. You need two people, one at the wheel bleeder nipple another at the fluid reservoir under the bonnet. you apply air pressure to the fluid under the bonnet by drilling a small hole in the screw cap and holding an air hose to the hole, thus pressurising the reservoir. Then get the bloke at the wheel to loosen the wheel bleeder nipple and let the air blow the fluid through till you get the bubbles out. Then tighten the nipple. Do the same on each wheel. Took about 10 minutes to fix the brakes and an afternoon at the pub at our expense to say thanks. If nothing else works give it a try.
Cheers.