Oldsmobile/Buick Repair: Location of master cylinder?, olds cutlass supreme, olds cutlass

Question
I have a '93 Olds Cutlass Supreme, 6 cyl with twin dual cams (yeah, yeah, I know) and the brakes are acting up.  I had the front brakes done in September and they told me my rears were good until at least spring.  But, the brakes have gone spongey on me and when I first start the vehicle, I have practically no brakes, having to really dig into the brake pedal with my foot to stop.  I want to check the brake fluid, but where the heck is it?  Nothing seems to be where you'd expect it in this car.

Though, if you suspect something else, let me hear.  This car is costing me so much in repairs that I can barely afford to take it in, so I'm hoping it's something I can take care of on my own.  However, I certainly will scrape up the money if needed because I drive freeway every day and I'm adverse to dying.  ;)

Thank you.

Sonya  

Answer
Hello Sonya,
Sounds like you might have a vacuum leak somewhere.
Lets check the brake booster first.

Get in the car, with the engine not running, and press and release the brakes several times. That will remove any stored vacuum, which should be in the booster.

Now, press your foot against the brake pedal, and hold moderate pressure, like if you were doing a normal stop.
While holding the pressure, start the engine.

If your brake pedal goes down further when the engine starts, then the booster is working. Not to say it might not have a vacuum leak, but it is working.

Take your foot off the pedal, and then shut the engine off.

Apply the brake pedal again a few times. Each application should feel just a little bit different, till all the vacuum is gone again.
If it feels like that, the booster is probably storing vacuum as it should.

If the brakes feel the exact same each time, the booster may be leaking, or the check valve in the vacuum hose to the booster from the engine may be leaking.

The booster and master cylinder should be under the hood, right in front of the driver. That is also where the reservoir for the brakes is. Make sure it is full of fluid on both ends.

I would also get down, and look under the car, at the insides of each tire, to see if any are wet with brake fluid, indicating a wheel cylinder, or brake line leak.

Van