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Stiff brake pedal; Brakes
Topic Started: Sep 17 2012, 02:58 PM (1,115 Views)
kirk343
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I've got a 1999 Metro with 1.0 3 cylinder with 288,000 miles. Recently my brake pedal became very spongy and stiff. I've got brakes on the car but you really have to stand on the pedal to actuate the brakes. I replaced the brake booster to no avail. My vacuum lines are clear from the booster to the intake. There is a vacuum check valve in the rubber hose coming out of the brake booster that I though may be bad but of course they are discontinuted. Has anyone else ran into this problem?
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Coche Blanco
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Troll Certified

Have you tried replacing the vacuum line?
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starscream5000
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Got 70 MPG?

Have you bled the brakes as well? Air bubbles in the brake lines will give you a spongy feel.
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t3ragtop
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Turbo3 and Twincam Tweaker

you have conflicting symptoms. :D

sponginess generally indicates air in the lines as stated above. the pedal hardness is another thing.

it sounds to me like the brake master is pooched. the rubber seals on the brake master piston have to clear a return hole when the pedal comes back to it's home position. old rubber seals tend to swell up and when they do, they don't clear the return hole which traps the hydraulic pressure in the lines and causes a hard pedal and poor braking effect.

another thing can cause a similar condition and that's old rubber brake hoses. they swell up, too, and cause a condition where you have to stand on the pedal to force fluid through the lines. once you force brake fluid through the swelled hoses, the fluid cannot easily return to the master cylinder reservoir and ends up trapped in the calipers.

the additinal condition for swelled hoses is that the brakes drag like crazy and the rotors get super hot. you can feel the brakes dragging and smell a stink like burning brake linings.
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kirk343
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starscream5000
Sep 17 2012, 03:18 PM
Have you bled the brakes as well? Air bubbles in the brake lines will give you a spongy feel.
Yep. Ive even ran a completely new line from the booster to the intake. Ive also bled the brakes all the way around. They are spongy for sure but the hard pedal is the main problem. Could the master cylinder be froze?
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kirk343
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Ill replace master and see what happens. This gradually started happening. At first it was happening about every third or fourth push and then it gradually happened all the time
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t3ragtop
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Turbo3 and Twincam Tweaker

don't forget to take a hard look at those rubber hoses to the calipers and wheel cylinders. if they're more than a few years old they can be bad. they aren't that expensive.

when they swell up, usually from water contamination of the brake fluid (which is hygroscopic,) they lose a considerable amount of their flexibility. if they feel stiff when you try to flex them, they probably need to be replaced.
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busteriver
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My guess is, all your questions will be answered if you tear down your master cylinder and look at the plunger.
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iamgeo
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Big League

I had a hard pedal on my '98. Found out the problem was the short brake vacuum hose from the intake manifold to the metal line. Was almost completely plugged with what I assume was carbon.
Changed just that hose and the brakes work perfectly.
You stated that you replaced the hose. Did you clean the nipple on the intake manifold? Perhaps it is clogged with carbon.
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