Brake Pedal Goes To The Floor!

DANIELSGLOCK

MEMBER
2003 MERCURY SABLE
3.0L
V6
FWD
AUTOMATIC
140,000 MILES

I was driving yesterday and had to get on the brakes kinda hard because of someone pulling out in front of me. Thats when the pedal went all the way to the floor and has remained that way since. No pressure whatsoever! I checked the fluid in the MC and it was a touch low so I filled it and tried pumping the brakes back up, no luck with that. Does this sound like the wheel cylinder? I haven't found any leaks and the MC fluid is still full. None of the vacuum lines have come off or loose, not sure if that would affect anything or not. The brake lines are all in good shape with no bulges or leaks. What could be the source of this problem? I've checked everything I know to look for! Any help would be MUCH appreciated!

Saturday, December 12th, 2015 AT 7:49 PM

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,

This sounds like you could have a leak somewhere is the brake system or the seals inside the master cylinder are bad and not producing any pressure.

Check all the brake lines for any leaks. Pay close attention to the hoses that goes to the front calipers and the rear wheel cylinders. You might have to remove the brake drum to see if there is any leakage from the cylinder.

If the master cylinder seals go bad it will not allow the brake system to produce any pressure and the pedal will go to the floor.

Here is a helpful article:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

I have attached diagrams for your reference.

Please let me know of any questions.
Thank you.

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