Is my car safe to drive until I can get to a mechanic tomorrow?

If you life and car insurance is paid up... go ahead and drive the car. In other words the car is unsafe to drive, you know that or you wouldn't be asking. So don't drive the car.

That sounds like a bad booster, all right.

Yes, as long as you make allowances for the heavy brakes it is safe enough, but check your brake fluid level. A common cause of brake booster diaphragm failure (which you are describing) is leakage from the master cylinder.

The boosters are pretty pricey - when I priced one for my Volvo it was over $500. I got one from a wrecking yard for $60 and it lasted the remaining life of the car. If you can talk the mechanic into going with a wrecking yard part - some don't like to do that - it can save you a lot of money. You can look on www.car-part.com for "power brake booster" to see some of what is available in your area. Here in Arizona it pulls up about two pages of results between $50 and $100. If the mechanic doesn't want to go that way, it is a medium level DIY job - anybody who does basic brake work can change a brake booster and, if necessary, master cylinder.

And he will know when he pulls it out if the master cylinder is leaking - the fluid will be obvious. I do not recommend anything but new parts for master cylinders.

No, not a good idea to risk hitting someone, so park it for now and get a friend to give you a ride. Check under the hood with someone in the car with it running. Have them step on the brake pedal. A vacuum line plugs into the booster, is it off?

brake booster could be just a bad rubber hose that you could fix but could be power booster and yes prepare they are high and sure you can drive it brake will just be hard to push i wouldnt drive it if i didnt have too..grocery store sure brakes not going out its the power booster to brakes is what make them power brakes is part behind master where you add brake fluid big round black could be just a vaccum hose that runs it that you might cut or tape up an d get it to a shop

Driving when your brakes aren't working well is a pretty big risk to take.

Have you looked under the hood? You may just have a disconnected vacuum line.

The rapair could be expensive if it is the booster, or cheap if it's just a vacuum line.

i might discover a clean mechanic. Your engine has a pressurized device all the thank you to and including the reservoir and that crack does not enable the device to pressurize. Will it reason a topic. it particularly is a huge "it ought to", why possibility it.

i would not drive it. if you have an accident. you will be paying more.you won't know untill you take it in.