Mechanics

BRAKE PEDAL ALMOST TOUCHING FLOOR

1994 Pontiac Bonneville • 103,000 miles

While driving and applying the brakes, there is very little pedal resistance, the pedal nearly touches the floor, and the car travels further than what I'm used to before coming to a stop. This happened just this morning, so I turned around and went back home, slowly.

A quick look around reveals there was plenty of brake fluid and the front and rear brake pads look very good. What should I check next?
Avatar
Mbistro
September 29, 2011.



Think your going to need a new master cylinder


Docfixit
Sep 29, 2011.
That's what it was. Bought a new (as in, not rebuilt) master cylinder at AutoZone for $43.99

Thank you Docfixit


Tiny
Mbistro
Sep 30, 2011.
Glad to have helped


Docfixit
Sep 30, 2011.
Almost a year later, just 2 weeks short of an "anniversary, " I have little to no brake pedal. Same as before, I had to "plan" my stops further ahead of time on a slow trip home. This time however, I also have an ABS warning light that stays illuminated. The light and the poor brake pedal event are not exactly in sync, I started seeing this light maybe a week or so beforehand. I mention this only for being complete with my symptoms, as it may or may not be directly related.

I went straight to the master cylinder this time. I just replaced it, bench bleeding the new one and installing it. Then did the ritual bleeding with an assistant pushing and holding the brake pedal. When the car is off, there is plenty of firm brake pedal, but when the car is started the pedal goes way down, nearly touching the floor. So I tried bleeding some more, the master cylinder itself and also at each of the wheels. Still no luck. When bleeding, there was little to no fluid, suggesting no air in the lines.

Someone at the parts store suggested the other culprit could be the brake booster. Is replacing the booster the next logical step? I want to be sure there isn't anything else I can try before having to crawl under the dash.

To summarize, the brake pedal goes way down when the car is started/running. I replaced the master cylinder. There is enough brake to stop the car if I put it in gear, and let it idle forward/backward in my driveway. I also have the ABS light that stays on.


Tiny
Mbistro
Sep 15, 2012.
*** UPDATE ***
I think I found the likely problem. After noticing the brake fluid reservoir went down, I found a leak under the car, as shown in the photo. But I don't know what that rusty thing is. Does anyone know? Thanks for any help.


Tiny
Mbistro
Sep 15, 2012.