My brake fluid all leaked out!

[Natty]

I started up my car to drive it for the first time in the last 8 days and the brake pedal went to the floor and barely, barely "bit." I popped the hood (it's 20 degrees F outside!) and there is barely any brake fluid left in the reservoir.

The big round black thing that the master cylinder bolts into (brake servo, brake booster, whichever you want to call it) has alot of paint eaten off of it. It looks like fluid suddenly leaked out. There is a big puddle under my car.

My question is what happened? It all leaked out when it wasn't being driven. I am guessing the cold and the fact that it sat for a week? Would there be a gasket between the master cylinder and the round black brake servo that might have burst due to the cold? Or would it be the master cylinder?

Oh, I searched and got nothing.

Here is a diagram:
http://www.carfiche.com/s13/4/a03.gif
It's leaking where 460 meets 470.

Any help is appreciated! Thanks in advance.

Jeff

[AKADriver]

Time for a new master cylinder. Probably the booster, too, if brake fluid leaked into it. There isn't supposed to be fluid the booster.

[Natty]

Originally posted by AKADriver
Time for a new master cylinder. Probably the booster, too, if brake fluid leaked into it. There isn't supposed to be fluid the booster.
Eh, I was afraid of that. I can get a rebuilt MC for $55 though. Does the brake booster just have somthing like a centrifuge spinning to create pressure? I can see how fluid in there would be bad.

And I have an autox on Saturday and Monday! Arg, I hope I can fix it by then.
Jeff

[AKADriver]

The brake booster is just a simple vacuum diaphragm. When you step on the pedal, it opens a valve so that one side of the diaphragm is at atmospheric pressure and the other side is at a vacuum. The movement of the diaphragm applies the brakes. When you release the pedal it closes the valve, both sides get equal vacuum, and return springs release the brakes.

[Natty]

Okay, that sounds about like what I thought.

One more. Does anyone think there is seal that could go bad. I can imagine that if there was, a mechanic in a college town would lie and say I need the master and servo replaced. It sounds bad, I know, but I am an 18 year old how doesn't know jack and I am all alone in a college town :(

Jeff

[kandyflip445]

If it's the cup seals in the MC then it shouldn't be hard to just rebuild it yourself. I've done a coupe of them. But if you don't have the time or the resources(books to get directions;) ) then just buy a new one(or rebuilt). And yeah if fluid got in your booster then just get a new one. Can't think why it would do that just cause it got cold though. Unless by some off chance your brake fluid was left exposed a long time, had soaked up a lot of water and expanded and ruined the cup seals....but I don't know....:rolleyes: