604Ryder

after i did the 5 lug swap on my car my brakes havent worked (i swapped the brakes from my parts car) anytime i fill up the master cylinder but it slowly leaks out. most the time its empties out overnight. i tried to check where the leak was coming from but was unable to find anything yet. im very tempted to just buy new calipers and ss lines. but if thers a way i can make the old brakes work please do tell

WAYNE88N/A

Man, you REALLY need to figure out exactly where the fluid's going before we can help you...

Back into the brake booster?
Under the master cylinder?
At one of the bleeder screws on the brakes?

BlaCkPlaGUE

Thats scary. Since you can't see the leak, thats the worst part. Have a friend slam the brakes while you look for anything 'spraying' lol.

If its really clean down there, its gonna be hard to see the brake fluid running, but look and touch everywhere the brake fluid goes, you'll find it eventually. Either that, or you got some crazy air in the brakes, im not to sure.

DocMazda

I just took my car out for a little turn on the twisties last night after i fixed my oil leak. Was pretty sure i had a brake fluid leak, but wasnt sure. I left the car sitting out overnight in a clean portion of the driveway. no oil (woowoo!!), but i saw another fluid leaking from my car. tried to locate the source. It is from the area of the brake fluid resevoir. Tried searching for anything that had remnants of brake fluid on it. it appears that the blower motor (i believe it to be the blower motor) on the drivers side right on the firewall had a little bit of fluid on the bottom of it. it that area sits just below the bottom of the brake fluid resevoir. I have never touched the brake cylinder or anything like that. in fact, i dont really know what the hell that stuff looks like. seems like one of the screws would just be loose. but i dont know, so please disregard that portion of the message. i just know theres brake fluid spatter on the bottom of the blower fan on the drivers side in the engine compartment. and the only thing there is the bottom of the fluid resevoir. will continue to search threads (as i always do). some help would be great!!

Thanks in advance,
Ry.

nopistons

Blower fan on the DRIVER'S side? Nope. Sounds like you're describing the power brake booster. Do you know what that is/looks like? It's the thing to which the master cylinder is bolted. As Wayne said, your brake fluid is probably leaking into the booster, which is why you aren't seeing any external leaks. If you're not knowledgeable about the braking system, find someone who is to help you. If it is leaking into the booster, you'll need to either rebuild your master or buy a new one.

JDUBrx7

When i restored my brake system, new rotors, calipers, master and slave cylenders, pads and wheel bearings. I didnt tighten down my passenger side front caliper brake line enough. Was loosing fluid just lie ku describe. Check the insides of your wheels, if u find one that is semi wet and REAL dirty, that is your source.

DocMazda

thanks for the help guys. I am going to try to pull the car into the garage tomorrow and look for the leak between class and before i go to work. Hopefully i will spot exactly where it is leaking from. i think that would be a better idea of what is leaking. also, arent the booster and master cylinder different items? would the cylinder need to be replaced if the booster were damaged?

Thanks,
Ry.

Syonyk

I second the "have a friend stand on the brakes while you look for the spray" idea. Heck, if it's quiet, you might even hear it.

The master cylinder and brake booster are indeed different items, but if your master cylinder is leaking brake fluid into the brake booster, it's probably a good bet that both are in need of replacement (well, at least the booster... you should be able to rebuild the master cylinder).

-=Russ=-

nopistons

Unlikely that the booster is bad. If it were, you'd notice the "hard" brake pedal all of a sudden. It would be similar to going from power steering to no power steering. When the master cyl leaks into the booster, it's just that the rear seal on the master has worn out, and the fluid goes past it and into the booster, often without any adverse effect on braking, because that rear section of the master is not under pressure when you apply the brakes - It's the drip-seal section for the reservoir above. Simply removing the master (you may be able to do this without disconnecting the brake lines - Just don't pull it out any more than necessary) and running a finger under the back of the master where the pushrod goes in will tell you if it's leaking or not.

DocMazda

whoa...okay, when my friend and i bled the brakes, i noticed that my brakes were damn near rock solid. then it started to let up some whenever i started the car and pushed the pedal a few more times. "okay, well my car has abs (although the abs light is on, so i might as well not have abs right?) so maybe that has some thing to do with it". i drive it some, pedal feels great. the next morning, no brake fluid, huge puddle under my car. damnation....so, you say a rock hard pedal is the booster? do you think i should rebuild the master cylinder as well? this will be my first brake venture, so i am kind of nervous about all of this.

Thanks for all your help guys,
Ryan Shannon.

Tofuball

If my car sits for a long time, my MBC leaks. If I drive it regularly, it is fine.

One day, I opened up my booster vac line and found break fluid in it . . .

You might check there :-p

nopistons

You say the pedal was hard when you bled the brakes, and then "let up some" whenever you started the car. That's because when the car isn't running, the booster has 2 or 3 pushes of the pedal in reserve until all of the vacuum in it is used up. (It works by vacuum generated in the engine's intake manifold. That's why it's connected to the engine by a hose.) When that vacuum is gone, (when the engine is off) so is the "power" effect for the brakes, so the pedal SHOULD be rock hard if you step on it a few times with the enigine off. The first thing you need to do is to find the source of the leak. Only then can you proceed.

DocMazda

okay thats cool. now i am not freaking out so much. i will go check.

GTRay

word of advice. if you can't distinguish between a brake booster and blower motor - don't attempt to rebuild the master cylinder or brake booster.

a leak between the booster and master cylinder is common on almost all cars. i see it all the time. typical procedure is replacement of the master cylinder.

replace it, don't try to rebuild it - you'll be doing it again in no time.

also, make sure you clean up any brake fluid residue - it is a very corrosive agent on automotive finishes.


Ray

nopistons

Ryan - I'm afraid that I have to agree with GTRay above. It sounds like you're just starting out in car repair, and although I don't want to dampen your enthusiasm for it, the braking system is not the place to start your automotive education. A mistake there could have catastrophic consequences for you, or someone else, on the road. If you were bleeding the brakes without the engine running, you're going about it all wrong at even the most basic level, so getting into parts replacement may not be a good idea right now. Don't guess at what you're doing when it comes to the brakes. Find someone knowledgeable to help you, or take it to a shop. There's only so much we here can help you with, without having the car in front of us.

DocMazda

actually, i found that the brake leak is coming from what looks like the back of the brake booster. I know i could seriously jack up my cars braking system trying to do this myself. But, my dad will help me with the majority of things. So, i know it is the brake booster that is leaking. It is leaking from the back of the unit (almost like the inside diaphragm is not seating properly, or a seal is gone). However, i am staring at the fsm right now, and the only seal that is labeled is the one that seals the front shell assembly with the pushrod of the booster. Not sure about rebuilding a booster, i think just purchasing another one would be a hell of a lot easier than cracking it apart. My dad wants me to buy a new seal kit or rebuild it (of course, he is a physics enginneer and just wants to know what stuff looks like taken apart. I have to admit i am curious myself. however, i am not too excited about putting that back into the vehicle if it is not rebuilt right. although it does look much easier than most things) I am thinking i may just purchase a new one, and then just take that one apart, and see what it is like (i learn by having stuff in front of me...pictures can only do so much). thanks for the help guys, as always, very informative!!!