HELP: I lost my brakes today! Please diagnose problem

[DamnedButDetermined]

I am cruising at around 30mph down a two lane road, when someone cuts in front of me suddenly. I slammed on the brakes, and the pedal seemed as usaul, then all of a sudden the pedal dropped an inch and turned rock solid. I lost about 90% of my braking ability and i have to really push like hell to get them to work. I checked under the hood when i got to school and looked at the master cylinder and the brake booster, for leaks. Everything seems to check out, and have absolutely zero idea of what happened.

I finally fixed my clutch today and now my brakes are flocked up! I just can't believe my luck:mad: :(

-DbD-

[Dousan_PG]

bleed your brakes
visual inspection-how lines mate up, hard lines, etc
check lines for leakage/cracking/holes
check your MC

what DOT of fluid do you use?

start w/ that.

[N1ceDrgn]

I agree, bleed your brakes. It sounds like the master isn't working right anymore. From what you described, you're doing the work for the master now. Try bleeding them and see if the fluid drains out/ fluid level drops. Either that or the arm from your pedal to the master, check that out too.

[HippoSleek]

I agree w/ dousan. Take some time under/down there and check everything out.

Also think about anything you might have done that could effect connections or leaks in the braking system (like servicing or bumping a certain area while doing the clutch, etc.). Basically anything that might introduce a leak. Remeber, even if fluid isn't necessarily coming out, if air could get in, there is a problem.

[DamnedButDetermined]

Ok, thanks for the suggestions! They are all very good. One question though. I have had air in my brakes before and air in my clutch line. This is a totally different feeling.

Here is the best way i can discribe it...When you take off a brake line and lost of air gets in it become extremely easy to push in the pedal. The more you bleed the brakes the harder it gets to push in the pedal. What i am feeling resembles a completely air free brake line, but instead of DOT3 fluid using cement mix!!!!

On my way home from school a few minutes ago i was playing around with the pedal feel, and i figured that if i really push hard (and i mean really hard) on the pedal the brakes wopuld lock up. I just couldn't generate enough force to lock them up, and i am pretty leg strong. :rolleyes: been working out lately:rolleyes:

But i will do as much examining as i can in the morning.

peace out,
-DbD-

[hotdogg]

it sounds to me like either a brake line, or your master cylinder is clogged up. more than likely your master cylinder since none of the brakes are working very good. you could try taking off your m/c, putting it in a vice with no lines attached and pumping it till you get fluid coming out of all of the ports. once you finish it will probably take forever to bleed again, but it may solve your problem.

[mrmephistopheles]

Check the vacuum line going to the brake booster. Sounds like your brake booster is becoming ineffective and you're forced to put out more effort.

-Kevin

[HippoSleek]

I'm with Kevin -- booster related.

Good clarification - I think we all read "pedal dropped an inch" to mean air.

[DamnedButDetermined]

oh forgot to tell you that it is a 1990 hatch if that makes any difference


I am going to look at it now and will poste my findings in a few!

[Dousan_PG]

wht DOT brake fluid do you use?
iirc, 4 and 5 require more changes and flushes. but dont quote me on that. i use DOT 3 castrol or something. never had a problem

[DamnedButDetermined]

Wow...Check this sh!t out...

I checked everything you guys told me too and it all checks out.

Today when i was driving it i kind of heard a noise from the pedal area when i hit the brakes. I crwl down in under the steering column and push in the brake pedal and hear a hissing noise. At first it felt like it was blowing air into the cockpit, but luckily there was some dust nearby that I saw get suck into the firewall. Now i don't really know how a brake booster works yet (need to check out How Stuff Works.com) but i am guessing this hissing isn't very good at sall. Also when i hold in the brake pedal I can feel and hear the engine act funny, then when i let off the pedal it goes back to normal idle.

If i haven't clarified enough the part that is actuallt sucking is where the silver rod goes into the firewall through a black rubber boot. That is were the dust got sucked into.

Hopefully this expaination clears things up for some people, but i am a little confused. Hopefully HSW.com will clear it up for me.

thanks,
-DbD-

[DamnedButDetermined]

Please help me out here. I figured out that the engine creates a vacuum and that is what makes the booster work. This vacuum helps push the primary and seocndary cylinders in the master cylinder. Since i seem to have a vacuum leak right at the firewall, the vacuum is not present, therefore it takes ALOT of strenght to stop the car. It doesn't seem to be dangerous, but it is inconveniant. I don't have any money right now to spend on this repair, so if someone knows of a seal i can replace or something to that matter please poste.

I really hope i don't have to get a whole new brake booster.

here is a picture of how a brake booster and master cylinder work...

well nevermind it won't let me do it so here is a link...

http://www.howstuffworks.com/power-brake2.htm

[240 2NR]

Well you're almost there. Now you just need to find the leak. Could just be a loose vacuum hose clamp, or you could need a new booster (not that expensive really, though the install may be tricky, I haven't done one, but plan to). Start the car, have a friend pump the brakes and find the leak. You can hear it so it shouldn't be that hard to locate.