Weak Brakes (searched)

Recently my brakes have gone downhill and I cant figure out why. Occasionally they will go to the floor or be fairly weak and not build up pressure even after pumping the brakes. Since they have gotten weak, they have went to the floor 3-4 times, slowly stopping the vehicle instead of not stopping it at all.

There arent any signs of a busted or leaking wheel cylinder and the lines dont seem to be cracked anywhere. The pads aint new and they aint old, kinda in between. What do y'all think?

Sounds like a bad master cylinder, or booster.

Quick booster check.
With engine off pump pedal till its hard 3-4 pumps
Then with foot still pressing brake pedal start the car, if pedal sinks a little booster is good.
Usually when booster has gone bad more pedal effort is required
Mushy pedal is probably bad master cyl.
While presing pedal does it slowly sink to the floor? if yes replace master cyl.

Start with those, if these dont fix it there are some prety good brake check type wbesite other have linked to in the past, a quick search might turn those up also.

A booster failure will result in a hard pedal, not a sinking pedal. It's a mechanism that fails safe. Otherwise if your engine stalled you'd lose your brakes, right? A sinking pedal without a leak is a bad master cylinder.

Because modern vehicles have a dual master cylinder (separate front-rear on a Jeep, diagonal on some europeans), it's common for one section to fail while the other does not. When this happens you'll still get some braking down near the floor, just as you would if you had a leaking line.

The little rubber cups in the master cylinder are designed to expand outward under pressure, so a bad master cylinder will often sink slowly under moderate pressure even though it holds when you hit the brake harder, and it may fail intermittently for a while before it just fails altogether. Try it. If you can still get brakes when you slam it but if the pedal sinks under steady lighter pressure, you need a new master cylinder.

Oh, and just in case there's doubt: you need it now.

Have you bled the brakes anyway? I had a sinking pedal after WF, my getting denied on a hill climb had sucked air into the MC. Getting an air bubble out of that is a PITA, after I had it bled properly I've not had any trouble since.
What's the fluid level look like, mine was low enough to suck air into the front circuit.

XJ88User said:

Sounds like a bad master cylinder, or booster.

(edit -1.) With engine off pump pedal till its hard 3-4 pumps, then with foot still pressing brake pedal start the car, if pedal sinks a little booster is good.
(edit - 2.) Usually when booster has gone bad more pedal effort is required
(edit - 3.) Mushy pedal is probably bad master cyl.
(edit - 4.) While presing pedal does it slowly sink to the floor? if yes replace master cyl.

Click to expand...

guess i forgot to break it in to steps to make my self clear.

Matthew Currie said:

A booster failure will result in a hard pedal, not a sinking pedal. It's a mechanism that fails safe. Otherwise if your engine stalled you'd lose your brakes, right? A sinking pedal without a leak is a bad master cylinder.

Click to expand...

Matthew is correct he just used a few more words is all.

XJ88User said:

guess i forgot to break it in to steps to make my self clear.



Matthew is correct he just used a few more words is all.

Click to expand...

I realize your test procedure was correct, and that you understand the situation, but I sort of took issue with your use of the word "usually." This subject comes up often, and it seems that many people do not realize that the addition of a power brake booster does not create any gap in the linkage of pedal to master cylinder, so though a bad booster will cause a loss of assist, it will not mimic a hydraulic failure.*

*For the nitpickers, all right, that may not be true absolutely 100%, but if you are in that situation, my advice is to get rid of your Citroen.:explosion