Some guy in a Taurus pulled out of his driveway in front of me and I had to lock it up to keep from hitting him. The car stopped fine, so I continued on my way to the gym. On the way back it was fine...until I was stopped at a red light. Then out of the blue the pedal goes all the way to the floor, and I hear a hissing sound when I hit the brake pedal. The brakes barely slowed the car down, and I had to drive home in low gear and pump the brakes to get anything out of them. The brake light stayed off. What do you think? Bad brake booster? If so, any recommendations on a replacement? I figure that a stock one for an '87 5.0 would be unobtainable today, but I could be wrong...
Edit: talked to my neighbor of 30 years who is also our mechanic. He's going to see if he can fix it tomorrow...here's hoping he can get what he needs...
My first guess would be booster too, but check your fluid level. If you push really hard with a bad booster, you should still have brakes although the pedal may seems so hard to push you think not.
Check for a popped rubber line in front or rear too.
Yeah, he mentioned the fluid too, that it could be a leak. I told him to check everything. The sick part is that Saturday I was going to head to NJ for a 11" brake upgrade courtesy of Sick88Tbird. Hopefully I can still make it :disappoin
its the booster.. my 83 did it when I got it... its not fun jamming your foot under the pedal doing 45 down a busy road because if you let off you're going to lock up...
Yup break booster. Had it happen when I got the car out this year. Leaving work hit the brakes at the intersection and it didn't do anything. Sounds like a snake under the dash.
Hmm.. I actually read your post this time. It sounds like you have a fluid issue of some sort. A booster will not keep your brakes from working if you can push the pedal down. A bad booster will either not want to go down (no vacuum, diaphragm busted, super hard pedal) or it will want to stay down, as so in my case.
You hearing a hissing noise is probably exposing a hole in the diaphragm by having to push the pedal down further.
Your booster is bad (not the cause of your failing brakes) and you have a leak somewhere. I would start at the rear end checking the wheel cylinders, they are usually the oldest part as no one pays attention to them. They tend to lay dormant near failing until excessive pressure is applied to them, I've blown out a few in extreme braking situations.
When wheel cylinders fail that dramatically, it's usually easy to tell...the inner sidewall of the tire will usually be soaked with fluid. Like you said John, when it rains, it pours...we'll get to that 11" brake conversion when we get to it...don't stress yourself out over it.
Good luck,
Don
like said before, its not limited to the brake booster b/c no booster, like said before wouldnt cause it to go to the floor. just for kicks take the rear tires off and the drum and inspect the cylnders. with it going to the floor, your pushing fluid out somewhere. if you had good brakes and no booster, you'd get a pedal feel as that of manual brakes.
Hmmm. Yeah, maybe it's both. When I had to jam on the brakes the pedal was REAL hard. It's been like that on and off for a few years, though most of the time the pedal was fine.
If the pedal goes to the floor, it sounds like the MC gave out.
I Had a 85 Mustang GT with bigger rear drums installed and when I tested the car from a 35 mph "brake slam" I heard a loud pop and I had busted the rear rubber brake line. Scared the hell out me.
Pedal went to the floor immediately.
Sorry to jack but I have the same problem, the pedel going to the floor and hissing under dash. I just did the WHOLE rear brake setup including new wheel cylinders, and I'm not leaking any fluid. Would this be the same thing, a bad booster?
On my 87 sport, I had the same problem, pedal to the floor with the snake, and once my booster was replaced (only the booster) the problem was solved.
i just hope its not a secondary leak on the primary piston in the master cylinder, but warbird prolly has the fix for ya. if you notice the rear brakes or front brakes not responding well or weak, it could be the master cylinder.
Generally,
Hissing only while pedal is actually moving down...
- Fluid leak. (pedal drops to floor)
- Booster's foam air filter bad, makes the "normal" sound louder.
Constant hissing, worse when the pedal is held down...
- Bad booster, not sealing internally. (hard to push pedal at all)
Constant hissing, doesn't change with pedal position...
- Leaking cruise control valve or hose. (normal braking)
Constant hissing, worse when the pedal is held down...
- Bad booster, not sealing internally. (hard to push pedal at all)
Sounds about right. Sometimes you hit the brakes there is brakes, sometimes it just hisses and goes to the floor. Fluid level doesn't change, bleed all the brakes and build the rear from scratch. Fronts are soon when I do the 11" brakes.
I logged on this morning with the same problem.
I also get the hissing sound, the pedle goes straight to the floor, and no brakes. The m/c fliud level is fine. I didnt see any fliud on the ground, but I didnt check the inner tires or pull a wheel.
Seems like I should still have front brakes if the rears are bad.
K, first things to check when you get a hissing:
- Make sure the brake booster check valve (where the large vacuum line from the manifold attaches to the booster) is properly seated. It is designed so that you can have a slight attachment angle and still not leak...but double check it anyway. Might need pushed in, or replaced (it's a $5 HELP! part). Also, inspect the vacuum line for cracks.
- If your car was originally equipped with the automatic parking brake release option, you'll have a thin white vacuum line going from the B/R port on the vacuum tee under the hood, through a hole in the center of the firewall, and down to a white collar at the base of the steering column, near the brake pedal. Make sure that line is attached (or capped off), or that the line didn't break.
Otherwise you're more than likely looking at a new booster.
In the winter time, the check valve in my t-bird would freeze...after letting it idle for 10 minutes, I had power brakes again.
i have the same problem to but i figured that out where the hissing/ bubbling sound is coming from and its coming from the brake booster. so is it better to replace the master cylinder to at the same time or just replace the brake booster?