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Discussion Starter #1
1999 NB, 2.0L 5 speed
Driving home from work today I suddenly lost all pedal pressure. Fortunately I know how to drive a 5 speed with no brakes (lots of practice with cheap cars as a kid). Got it home, pulled the intake tubing to get to the master cylinder. Checked the cylinder, no leaks inside the car or out. Checked the calipers, pads and rotors, probably need new rotors soon, but the pads have decent meat on them, no leaks. Checked the brake booster, holds solid vacuum, as soon as I pulled the vacuum line it hissed as it sucked in air, so both the check valve and the booster are good. Got in checked the unassisted pedal pressure, it's firm again...Reassembled the car, started and checked the assisted pressure, feels normal...Test drove it up and down the street hitting the brakes like a nervous grandmother with bad eye sight...no problems...

I'm grateful for the miracle, but can anyone shed some light on this?
 

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Discussion Starter #3
Anything having to do with soft brakes has nothing to do with the vacuum lines or brake booster. If the brake booster goes it will feel like you have unassisted brakes making the pedal feel hard and difficult to stop. If the pedal feels soft for any reason its typical a bad master cylinder, leaking like or caliper.

I think I figured out what happened. I don't think I dropped the e-brake all the way when I left my parking space and the light pressure on the rear pads caused the pads to heat up evaporating the fluid in the lines which would act much like air in the lines until it cools enough to re-liquefy into brake fluid again. If that's the case the worst that I need to do is flush the lines and replace the rear pads and rotors. So far everything seems fine though.
 

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I think I figured out what happened. I don't think I dropped the e-brake all the way when I left my parking space and the light pressure on the rear pads caused the pads to heat up evaporating the fluid in the lines which would act much like air in the lines until it cools enough to re-liquefy into brake fluid again. If that's the case the worst that I need to do is flush the lines and replace the rear pads and rotors. So far everything seems fine though.
Likely possibility. I would definitely flush the brakes with some new fluid if this were the case. And yes, it cannot hurt to go over the vacuum lines while you are at it. You could also have a slipping cup seal internal to the master cylinder.

For a counterpoint, I had the booster fail in my '01 TDI last week, and in a completely different way. The venting valves for the rear chamber of the booster would open completely when I would attempt a nice and "easy" stop. When they completely opened, they completely vented the rear chamber and applied the brakes full force. And on a few occasions, they actually held the brakes on when I would try to accelerate away from a stop. That was fun week, and it was even more fun replacing it.
 

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Discussion Starter #5
Well, so far so good. I really think I just didn't drop the ebrake all the way down. I've caught myself a couple of times since where I thought the handle was down but I always double check now.
 

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Well, so far so good. I really think I just didn't drop the ebrake all the way down. I've caught myself a couple of times since where I thought the handle was down but I always double check now.
Maybe re-adjust your ebrake switch? My 'brake' light doesn't go out until my ebrake is past the 'clicks' and almost fully rested. It would be impossible for me to leave it clicked in any position with the warning light blinding me.
 

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Discussion Starter #7
Maybe re-adjust your ebrake switch? My 'brake' light doesn't go out until my ebrake is past the 'clicks' and almost fully rested. It would be impossible for me to leave it clicked in any position with the warning light blinding me.
Probably a good idea, but I'll get around to that eventually. Along with the 50 other things I need to figure out, like why it keeps destroying catalytic converters.
 
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