whats wrong with my brakes
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From: 3rd rock
whats wrong with my brakes
Today while driving around I had an unexpected surprise with my brakes. I'm not sure what is causing it and I need some help. The problem occurs while stepping on the break pedal what happens in the pedal almost goes down to the floor almost no pressure at all, after pumping the pedal 4-5 times the resistance starts to build on the pedal and the breaks work fine again, after a few minutes of continual non stop driving the breaks do it again. I checked the break fluid resivor and it's full.
The Lady's Man
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From: south O.C. california
Sean, read his last sentence. MIne just did this also. Turned out the brake master was bad. Start with Heinrichs suggestion but I wouldn't want to be caught without brake at a bad time. Been working on the brakes at all? Air shouldn't just get in the system..
Mine went like that on the way to work. First few pumps brought pressure back up then they went away. After getting to work and letting the car sit they had pressure again. Resevoir on my car showed full to. Not exactly the sam as your condition but close enough that I'd consider a new master cylinder.
Mine went like that on the way to work. First few pumps brought pressure back up then they went away. After getting to work and letting the car sit they had pressure again. Resevoir on my car showed full to. Not exactly the sam as your condition but close enough that I'd consider a new master cylinder.
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From: Mountains of GA!
Brake fluid is hydroscopic....it ATTRACTS water. Unless you do a thorough full bleed, you can get tiny bubbles (Thanks, Don Ho...and his sisters - 'Stanky' and "Nappy Headed'). Do a FULL, THOROUGH bleed.
ALSO - if you use the wrong brake fluid (DOT 5, IIRC??) it is NOT made for our cars, and will cause problems. Use a quality fluid - most ALL of the hardcores here use 'Super Blue'. It comes in blue and also in gold. By alternating the colors when you bleed, you can watch the color change to help ensure you get a thorough flush. The 'Power Bleeder' sold by 928 Spec and others is a GREAT tool!
ALSO - if you use the wrong brake fluid (DOT 5, IIRC??) it is NOT made for our cars, and will cause problems. Use a quality fluid - most ALL of the hardcores here use 'Super Blue'. It comes in blue and also in gold. By alternating the colors when you bleed, you can watch the color change to help ensure you get a thorough flush. The 'Power Bleeder' sold by 928 Spec and others is a GREAT tool!
The Lady's Man
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From: south O.C. california
If he hasn't been working or doing anything to his brakes then he has an issue. Air does not just get into the brakes. Bleeding won't help unless he finds the source of the leak. If he has been working on them (which he doesn't state) then bleeding is the right way to go.
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Joined: Oct 2003
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From: Quartz Hill,CA.
Agree, brakes are not going to attract water or air overnight to have that much of an impact so quickly. A real issue exist-most likely a master cylinder. I would also inspect each wheel for any leaks. A bleed will not cure this sort of issue that occurs out of the blue.
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The Lady's Man
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From: south O.C. california
You have the same luck as me :-) I watched a couple guys replace one last year at Octoberfest and it didn't look that difficult. I just had Precision do mine because I needed the car back because it is my DD for now. Good luck!
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From: Mountains of GA!
It's a pretty easy job. FIgure about 45-60 minutes PLUS flush & bleed...
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From: Sydney AUS
Correct. DOT 5 is silicon based - completely different from DOT 4 or 3. It does have it's uses but don't put it in your 928 before doing a lot of research.
DOT 5.1 is compatible with 4 and 3 it just has a higher minimum boiling point.
Boiling point ranges Dry boiling point Wet boiling point
DOT 3 205°C (401°F) 140°C (284°F)
DOT 4 230°C (446°F) 155°C (311°F)
DOT 5 260°C (500°F) 180°C (356°F)
DOT 5.1 270°C (518°F) 191°C (375°F)
A quick check on the variety of brake fluids on the shelf in my garage suggests that DOT 4 fluids often surpass the 5.1 standard.
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From: Fremont, CA
If it is a 5-speed you mise well change the blue hose and read up on how to bleed the clutch master/slave. Replacing the master cylinder is a pretty easy job, getting a decently bled clutch master & slave can be a challenge.