HELP - Brake Problem

2000F150SAS

Well-Known Member
Joined
Jun 13, 2007
Location
Fuquay-Varina, NC
What is the problem?

1990 Bronco 2, 2 wheel drive, V6, 5 Spd.

If I sit still with my foot on the brake the pedal it keeps going down (slowly) until I let up and re-apply. In the morning when I first start the truck and take off the first couple of times when applying the brakes the brake pedal vibrates / chatters when pushed down.

No fluid leaking all checked and no fluid lost. I’m thinking Brake Booster due to the morning problem with lack of vacuum.

Please help.

Thanks, John
 
Does it have ABS
 
The back wheels did, but not anymore. We by passed the controller which is located under the truck. This as been without ABS for 10 months.

Thanks
 
My f350 does the same thing rear wheel sensor was out
 
I believe you have a ruptured vacuum assist booster, or a vac leak between your intake and your booster. Those stupis brake boosters are expensive sometimes too.

Does it make a little bit of a hiss (could be very subtle) when you're just sitting on the brakes?

I had mine go out on the S-10 Blazer and it would do the same thing until it tore, then almost no brakes at all.
 
Crashkott,

I'll need to check this week for that sound. I think it's a booster also since no fluid is leaking and I'm having no fluid lost.

Advance has it for $90 with new master cylinder or $60 without master cylinder.

Thanks:beer:
 
In my experience a falling pedal is almost always attributed to the MC. No fluid leaks anywhere visible because the internal seal is bad and the fluid is leaking back into the MC


the chatter and such, well I dont have a clue
 
SkyHiK5 said:
In my experience a falling pedal is almost always attributed to the MC. No fluid leaks anywhere visible because the internal seal is bad and the fluid is leaking back into the MC


the chatter and such, well I dont have a clue
Click to expand...
x2 probably the master leaking internally.
 
I checked for vacuum leaks last night and found nothing. The MC leaking sounds good but why is the problem worst for the first stop after starting the truck when it has been sitting? Is the MC leaking down and the fluid low from sitting??

Thanks, John
 
Hmmm, that could be.

You're relying on gravity and good seals to keep pressure in the system up when you're not standing on the pedal.

If you have a MC seal leaking back into the reservoir, that could cause the bad-1st-stop brakes.

rebuilt MC's are cheap enough though, so throw a new one in there.
 
x3 master cylinder. I suggest you look around at all the other components after the MC replacement. Often, when the MC craps out, other parts are just as bad or will go after good pressure is restored. Sticking front calipers and weaping rear slave cylinders are common in aged and wheeled rigs. If the fluid in the MC is dark, best flush the entire system. The discoloration is due to moisture corrosion. Chattering is the calipers...best take a look at those two. May be time to turn the rotors and put on new pads.

Have fun .........
 
It was the MC, replaced the MC and flused the lines with new fluid. They feel great.

Thanks all.:beer:
 
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