pump brakes and get a hard pedal but as soon as you release the pedal, the pedal goes to the floor

Asked by May 10, 2014 at 08:39 PM about the 1968 Mercury Cougar

Question type: Maintenance & Repair

Had a leaky proportioning valve. Replaced it, distribution block, master cylinder and all
front lines. Pre-bled the master cylinder and Bled brakes several but as soon as you
release the pedal, the pedal goes to the floor. All this done with the engine not running.
Does anyone have a suggestion on what is wrong?

5 Answers

105

Does it do it with the engine running? If not, you could have a vacuum leak maybe in the brake booster.

6,405

That valve should have a reset button on it at the top so try resetting it. Alos, open up the front brake bleeders and let them run for a few minutes keeping the master cylinder reservoir full while doing it. Good Luck, Kenny/MrBlueOval

6,405

I can't type today, LOL !!! The above should read "Also" not Alos.

85

sounds like you got a bad master cylinder, don't buy a rebuilt master cylinder, buy a brand new one, better be safe then sorry, and if their is a leak in the booster you will here the air escaping and the car will tremor when you push on the brake, My proportioning valve has been rebuilt and is original but I don't have a reset button on the valve.

1 out of 1 people think this is helpful.
85

did you bleed all 4 wheels,start from the back passenger side bleed it 3 times, then the back passenger driver side bleed it 3 times, next is the front start at the passenger side bleed it 3 times then go to the front driver side bleed it 3 times,

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