GAH!! Brake Fluid Disappeared! Pedal Has No Resistance w/ Car Running! HELP!

[rico05]

Intro:When we did my brakes about 16 months ago (BRembo blanks, Axxis MM pads, Goodridgle lines) we noticed that my rear calipers looked a little tired. About a month ago, I noticed that I was starting to lose fluid, and that the inside of my passenger side rear wheel has some brake fluid caked into crud in it. No biggie. Well, the brakes have been working fine none the less.

Long Version:Then, this morning (which HAS to be 55 degrees and raining LOL) I go outside and see that, when I start my car, the brake light won't go off. Hmmmm. I just checked the fluid last night, and it was just a hair under MAX. I pop the hood: WAY below MIN line. Damn! Then, I go to pull into the drive way.....NO RESISTANCE from the brake pedal. Goes straight to the floor. I fill the fluid, and pump the brakes with the car off and pressure returns. Whew. Well, I start the car and it won't keep pressure. The booster/MC was replaced by the last owner, and last night I did pull off the booster line from the manifold to rearrange some wiring for my gauges. But, after doing so, I drove around a lot last night with perfectly working brakes.

Short version: Lost fluid and brake pressure overnight. Brakes worked last night, now won't keep pressure when the car is running, but will with the car off. Any ideas? PLEASE HELP!!!!!!!!!

[Exar-Kun]

first problem:

" About a month ago, I noticed that I was starting to lose fluid, and that the inside of my passenger side rear wheel has some brake fluid caked into crud in it. No biggie."

Leaking brake fluid enough to cake a wheel...uhm yes, very BIG problem.

Its losing the pressure to the brakes via the vaccuum booster is what it sounds like to me, but I'd bet you've blown that caliper completely out.

-Chet

[rico05]

Well, I checked the fluid level as I had my girlfriend pump the brakes, and no fluid loss, so I dobut that the caliper is completly shot. But how could this problem arise with the car sitting all night? I literally drove it and the brakes were great as always less than 12 hours ago.

[rico05]

Well, I just pulled the wheel and caliper and I am embarassed to say that the caliper is blown. Could this be the reason that the pedal has no pressure LOL? Sorry for the freak out Chet, and I have learned my lesson!

But, is this the only reason for my funky pedal action?

[Exar-Kun]

Rico,

It's all good man. yes, they symptoms you describe would pin it to blown caliper. I'd repalce the PAIR (not just one) to ensure propper balance, ro rebuild them both. and go from there. Make sure you clean any brake fluid from any painted surface it may have gotten on..it EATS paint.

-Chet

[Kenrik]

You should have handled the problem when you first knew about it... it would suck to loose your breaks on the highway doing 70mph... consider yourself lucky and remember it's called preventive matenence for a reason

[rico05]

Ok, so I replaced the calipers. BUT, I still have crappy pedal feel...as in none. Once again, when the car is off, and I pump the brakes, I get full feel (aka rock hard LOL), but with the car running, there is little pressure (it has returned a bit since the new calipers/bleeding the brakes, but not like it was) I pulled the vac line off of the booster, with the car off, and there is a WOOSH of escaping pressurized air, so it is holding pressure. Any more ideas?

EDIT: I did some more NICO archive searching, and I checked for booster leak by listening (with the car on) around the brake pedal under the car. Also, the brakes DO in fact work...well. I just have to push the pedal much further to get any results. Also, my ebrake needed to be pulled much more to get it to work (previoulsy, I had it adjusted VERY tight, and I had to retighten it again....I assume this is unrealated and has to do with the fact that the ebrake cable was removed and replaced on the caliper) This really sucks, until 2 days ago, my brakes were bad a$$. Now they remind me of my gf's Cavalier

Further EDIT: I checked the FSM on booster inspection, and it is fine. I am going to try another bleed session, and see if that gets me anywhere.


Modified by rico05 at 4:54 PM 10/12/2005

[Exar-Kun]

You have stock rear brakes, yeah? Ensureing the rears are adjusted corectly and I assume you did align them little nubs on the piston to the slots in the pad?

Check your lines, also on the fronts if you did a 300zx conversion you definately want to ensure the fittings are ok. Sounds like if the calipers and lines are OK, the MC valve may be busted.

-Chet

[Dori Dori]

There may still be air in the lines. I would bleed, bleed, and bleed until you are 100% sure there is no air (on all 4 corners). I had to replace my rear calipers b/c like yours, one of them developed a small leak...remember that when there's leak, it can work both ways so a good amt of air could have made it into your system. This was a blessing in disguise though since my shop initially put super blue into my MC to see if I liked it. I didn't. Now I'm leak free and my pedal feels 100x better without that blue crap. Motul 600 4-eva dAwG.

Oh and why do you CA guys insist on starting crap w/ SR guys? "189cc's wasted"